Re: [RE-wrenches] NECPLUS Article

[boB Gudgel]

Joel Davidson wrote:
Interesting news item, but the link does not connect to the fire 
fighter report. Does someone have the correct report link?
In May 2010 the Fire Protection Research Foundation (FPRF) completed a 
one-year research project addressing photovoltaic (PV) power systems.  
The report, titled "Fire Fighter and Emergency Response for Solar 
Power Systems", is of direct interest to the NEC® community and is 
available for download on the FPRF website (at www.nfpa.org/foundation).






I am aware of the big Target roof PV fire in California, but this 
article mentions there are others.


Can someone site some of those other PV related fires ? Off list 
would be fine.


Thanks,
boB





- Original Message - From: 
To: "RE-wrenches" 
Sent: Thursday, August 05, 2010 2:17 PM
Subject: [RE-wrenches] NECPLUS Article



This may be of interest...from the NEC newsletter

http://www.necplus.org/Features/Pages/ThePoweroftheSunResearchinSupportofSafePhotovoltaicPower.aspx?sso=0 



Holt E. Kelly
Holtek Fireplace & Solar Products
500 Jewell Dr.
Waco TX. 76712
254-751-9111
www.holteksolar.com

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Re: [RE-wrenches] Voltage discrepancy

[boB Gudgel]

Drake Chamberlin wrote:
I called her back just now, and the voltage readings on the Mate, MX 
and Trimetric all match.  Humm.  

The batteries are 4, 4 1/2 year old, U.S. Battery L-16s wired in 24 
volt configuration.  It seems that I remember postings of Wrenches 
having problems with these batteries.  There is about 1 KW STC of PV 
on the roof. 





Might want to be careful of loose connections.  Maybe the MX was putting 
out some high(ish) current and there
was a voltage drop across that connection, and now they are reading the 
same because the current is
lower from the MX.  i.e.  high voltage at the terminals of the CC and 
lower at the actual battery terminals.


boB







At 12:12 PM 8/14/2010, you wrote:
Any way she can get a real voltmeter?  the MX60 has voltage 
calibration, so does the FX  it sounds like something is over 
charging, perhaps the generator run?   additonal details on battery 
bank size, array size and typical load. 
 
Darryl


--- On *Sat, 8/14/10, Drake Chamberlin 
//* wrote:



From: Drake Chamberlin 
Subject: [RE-wrenches] Voltage discrepancy
To: "RE-wrenches" 
Date: Saturday, August 14, 2010, 8:58 AM

Hello Wrenches,

I just got off the phone with an off grid system owner who has a
voltage discrepancy showing between the reading on her MX-60 and
both her Mate and Trimetric meter.  The MX-60 shows 28.8 V and
the Trimetric and the Mate both show around 25 volts.  The
batteries are using a tremendous amount of water.

Has anyone seen this scenario before?  Do you think the MX-60 is
bad?

Thanks,

Drake Chamberlin
Athens Electric
OH License 44810
CO License 3773
NABCEP TM  Certified PV Installer
Office - 740-448-7328
Mobile - 740-856-9648

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Drake Chamberlin
Athens Electric
OH License 44810
CO License 3773
NABCEP TM  Certified PV Installer
Office - 740-448-7328
Mobile - 740-856-9648



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Re: [RE-wrenches] Voltage discrepancy

[boB Gudgel]

Drake Chamberlin wrote:

boB,

Thanks,  I will check all connections when I get out there.  Is there 
anyway a loose connection could cook the batteries?


A loose connection, if it was like I described, would tend to 
under-charge the batteries.   I would think that
if there were ~that~ much of a voltage drop, and significant current, 
you'd have a pretty hot connection
somewhere.  Although, if the connection is bad enough, you might just 
get the CC to get to Absorb or
Float voltage and that would at least limit the current but maybe not 
enough.. 

Of course, loose connections may not be the problem, but that's what I 
look for first.
I would measure the voltage at the CC terminal block and see if it is 
telling the truth.


If the CC is telling the truth, then she may have a bad connection, and  
then

it's Warning Will Robinson !!

Could be intermittent too.   Then ya may want to start wiggling and 
banging on things.

It sure worked well with TV sets.

boB




Thanks,


Drake


At 03:16 PM 8/14/2010, you wrote:

Drake Chamberlin wrote:
I called her back just now, and the voltage readings on the Mate, MX 
and Trimetric all match.  Humm. 

The batteries are 4, 4 1/2 year old, U.S. Battery L-16s wired in 24 
volt configuration.  It seems that I remember postings of Wrenches 
having problems with these batteries.  There is about 1 KW STC of PV 
on the roof.


Might want to be careful of loose connections.  Maybe the MX was 
putting out some high(ish) current and there
was a voltage drop across that connection, and now they are reading 
the same because the current is
lower from the MX.  i.e.  high voltage at the terminals of the CC and 
lower at the actual battery terminals.


boB







At 12:12 PM 8/14/2010, you wrote:
Any way she can get a real voltmeter?  the MX60 has voltage 
calibration, so does the FX  it sounds like something is over 
charging, perhaps the generator run?   additonal details on battery 
bank size, array size and typical load.  Darryl


--- On *Sat, 8/14/10, Drake Chamberlin 
//* wrote:



From: Drake Chamberlin 
Subject: [RE-wrenches] Voltage discrepancy
To: "RE-wrenches" 
Date: Saturday, August 14, 2010, 8:58 AM

Hello Wrenches,

I just got off the phone with an off grid system owner who has a
voltage discrepancy showing between the reading on her MX-60 and
both her Mate and Trimetric meter.  The MX-60 shows 28.8 V and
the Trimetric and the Mate both show around 25 volts.  The
batteries are using a tremendous amount of water.

Has anyone seen this scenario before?  Do you think the MX-60 is
bad?

Thanks,

Drake Chamberlin
Athens Electric
OH License 44810
CO License 3773
NABCEP TM  Certified PV Installer
Office - 740-448-7328
Mobile - 740-856-9648

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Drake Chamberlin
Athens Electric
OH License 44810
CO License 3773
NABCEP TM  Certified PV Installer
Office - 740-448-7328
Mobile - 740-856-9648



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Re: [RE-wrenches] Voltage discrepancy

[boB Gudgel]

Jeff Oldham wrote:
I have seen this on my last 3 MX60 controllers and it is very 
frustrating and looks to be a design flaw. I can calibrate the meters 
to be accurate at either the Absorb point OR the Float point but NOT 
both!! Not only that but the meter calibrations tend to drift a bit in 
just a matter of days, just .1V not a big deal but anymore than that 
on a 12V sealed battery and it could be an issue. I spoke w/Outback 
about this and heard a mumbled "Ahh, uummm, yeah that is an issue". 
I'm guessing that you're seeing the same thing and when you spoke 
w/your customer again and the meters all agreed I'll bet it is because 
the MX was at the "line up point" of the other meters (just like a 
broken clock being correct twice a day!). The only way to live with 
this is to get the more important Absorb set point right on and take 
what you get on the lower end. It works and is usable but drives 
customers nuts when they have additional meters. In my experience the 
Tri-mets are dead on.




Jeff, what size wire from charge controller to the battery are you using 
??   The bigger the wire, the less the
I*R drop and the less the voltage discrepancy ~should~  be, at higher 
currents.


boB






From the Solar, Wind and Hydro powered office of Jeff 
Oldham/Regenerative SOLutions



*Notre Dame Certificates*
100% Online Programs in Negotiation Leadership and Mgmt. Enroll Today!
NotreDameOnline.com 




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Re: [RE-wrenches] Dog controller conflict with Outback inverter.

[boB Gudgel]

 On 8/27/2010 7:51 PM, cvso...@aol.com wrote:

Help!
   Has anyone delt with RF interference between a dog control device 
and GVFX3524.  It seems that some frequency in the inverter (or maybe 
the FlexMax 80) is cancelling the emitted signal from a dog control 
device which shocks the dog when the signal gets weak (dog too far 
from house).  Every time the inverter starts to sell, the collar on 
the dog starts shocking the animal.  Our only possible solution so far 
is to build a Faraday cage around the inverter to see if the 
interference is reduces sufficiently.  I have been looking at brass 
mesh, aluminum window screen, and copper mesh.  Any ideas?

John Blittersdorf
Central Vermont Solar & Wind.




First, I am quite surprised (Shocked actually !),  that the design of 
this dog

shock collar would allow it to shock without the proper coding from the
transmitter, weak signal or not.
I would not rule out calling the company that makes the shock collar too,
and their EMI susceptibility.  Maybe they have seen this problem before
and can have you change a code or might even replace with more secure unit ?
The interference that you might get from an inverter or charge 
controller just

shouldn't have this effect.

The lower the frequency of the dog collar signal, the smaller the mesh size
you can get away with.   But that assumes the RFI is coming directly from
the inverter or controller itself.  It's most likely coming from the wiring.

One thing to try, that is, to rule out (or in) the charge controller is 
to lower

the sell voltage so that it will sell for a few moments at night (from the
batteries),  when the CC would not be supplying power and radiating.

Hopefully you can test this without the use of the dog having to tell you
when it is being shocked !

That's my input for tonight.   I'm interested in what the dog collar company
has to say, for sure.

boB








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[RE-wrenches] RE Visio shapes files

[boB Gudgel]

Hello Wrenches.

Do any of you know where to find shape library files for drawing RE pix 
in Microsoft Visio ??


Solar, Wind, batteries, etc...

Thanks,
boB

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Re: [RE-wrenches] RE Visio shapes files

[boB Gudgel]

 On 9/5/2010 9:32 PM, William Miller wrote:

boB:

I have a set of template and stencil files on my web site at: 
http://www.millersolar.com/resources/resources.html


I never progressed beyond version 4.1T because it still works for me.  
You are probably using a newer version, but these files should be 
backwards compatible.


Good luck, and let me know if these are helpful.

William Miller




Thank you William (and the others who emailed)   That is exactly the 
kind of thing I was looking for !


Much appreciated !

boB








At 07:22 PM 9/5/2010, you wrote:



Hello Wrenches.

Do any of you know where to find shape library files for drawing RE 
pix in Microsoft Visio ??


Solar, Wind, batteries, etc...

Thanks,
boB

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No virus found in this incoming message.
Checked by AVG - www.avg.com 
Version: 8.5.441 / Virus Database: 271.1.1/3116 - Release Date: 
09/05/10 18:34:00


_Please note new e-mail address and domain:

_William Miller
Miller Solar
Voice :805-438-5600
email: will...@millersolar.com
http://millersolar.com
License No. C-10-773985


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Re: [RE-wrenches] RE Visio shapes files

[boB Gudgel]

 On 9/6/2010 2:50 PM, Glenn Burt wrote:


Care to share the wealth?

-Glenn



William appears to be the only resource on the planet !

Maybe I could try another planet ??

boB



*From:* re-wrenches-boun...@lists.re-wrenches.org 
[mailto:re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of *boB 
Gudgel

*Sent:* Monday, September 06, 2010 12:44 AM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] RE Visio shapes files

On 9/5/2010 9:32 PM, William Miller wrote:

boB:

I have a set of template and stencil files on my web site at: 
http://www.millersolar.com/resources/resources.html


I never progressed beyond version 4.1T because it still works for me.  
You are probably using a newer version, but these files should be 
backwards compatible.


Good luck, and let me know if these are helpful.

William Miller




Thank you William (and the others who emailed)   That is exactly the 
kind of thing I was looking for !


Much appreciated !

boB







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Re: [RE-wrenches] Inverter 1741 Listing Process

[boB Gudgel]

 On 10/8/2010 6:04 PM, Matt Lafferty wrote:

Hola Wrenches,
Does anybody know off the top of their head if the 
/"5-minute-wait-to-interconnect"/ function is tested on 100% of 
inverters produced? /(i.e. every single inverter is tested with AC & 
DC within the start parameters of the unit for at least 5 minutes)/

Thanks!
Matt Lafferty


Good question.  I bet it's not 100% tested because if the software does not
change, then they may just not wait the extra 5 minutes in order to save 
money on testing.

Or, maybe they do a random sampling for this test.

Theoretically, it shouldn't matter as long as the software does not change
and the hardware is tested enough in other ways, like, timers and clocks 
etc.



BTW, Nowadays, there are two options for manufacturers of grid 
interactive inverters

And the UL spec has gotten more stringent.

 One option  is that you have to have  the  code (software) blessed by 
the NRTL in a separate
process (another UL specification, (UL 1998 --Software in Programmable 
Components")


OR, if they don't go for that option, then if software changes need to 
be done to the
inverter, the inverter must (technically) go through the UL1741 listing 
process all over

again.

boB


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Re: [RE-wrenches] Mac compatibility with Modsine

[boB Gudgel]

 On 10/9/2010 3:07 PM, Carl Hansen wrote:

 Greetings,

   Does anyone know if newer Macintosh computers are still 
incompatible with Modsine inverters, and how about Mac loptops ?


   Thanks,
  Carl Hansen
  Hansen&Sun elect.



My Mac Book Pro (from early 2009) worked off of a cheap-O  12V cigarette 
lighter 150W Mod Sine
inverter while driving to MREF from Minnesota last year (I was in the 
back seat)  That is,

until we stopped for lunch and battery voltage dropped.

When we came back out of  the restaurant, the inverter was dead.   The 
battery voltage dropping is

the only thing I can think of that would have killed it.

I also seemed to notice that the Apple power supply got quite a bit 
hotter when running under

this waveform.  Not sure how much hotter exactly.

That's one experience.

boB




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Re: [RE-wrenches] Inverter 1741 Listing Process

[boB Gudgel]

 On 10/18/2010 9:53 PM, Matt Lafferty wrote:

Thanks for the info Dan and boB.
What production tests required to maintain listing? Do you happen to 
know if there is a different regimen for micro vs string vs central 
inverters?



You mean, a difference between the two when UL, ETL, CSA comes by for 
their pop inspection ??


Off hand, I don't  see why one inverter would be given any different 
kind of attention than the other
type.  The UL/ETL followup inspections are basically to make sure you 
are following the proper
manufacturing and testing processes such as, software version, 
verification that you are using
UL recognized  sources of parts and materials, hi-potting at the correct 
voltages, etc.



They are both grid-tie inverters so the testing processes are very similar.

 I'm sure that Dan will pick up on anything  important that I forgot.

boB


I'm working on developing a detailed commissioning procedure. Detailed 
yet generic. There will be at least two versions for inverters. One 
for string and one for central. In my book, central inverters have 
re-combiners (standalone or integral) and string inverters don't. I'm 
trying to understand which functions are tested in the factory on 
every unit so I can avoid unnecessary duplication by the commissioning 
people.

Thanks in advance for any light you can shed on the subject!
*/Matt Lafferty/*

*From:* re-wrenches-boun...@lists.re-wrenches.org 
[mailto:re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of *Exeltech

*Sent:* Monday, October 11, 2010 10:04 AM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] Inverter 1741 Listing Process

Matt,

The 5-minute delay is verified in the group of inverters sent to the 
test laboratory.  Then, as long as the software and hardware don't 
change, it's presumed the delay in all production units meets the 
value(s) measured in the tested units.


An alteration in either hardware OR software can result in a unit 
being required to completely re-test (as Bob pointed out).  NRTLs get 
copies of the source code and can and do periodically compare their 
copy as submitted with the original test units to the software being 
programmed into the inverters during production to verify it's the same.


NRTLs conduct unannounced "field audits" by simply showing up on site 
and randomly selecting various aspects of the product for verification 
-- including the software.


The overall UL1741 certification process is extremely complex, very 
time consuming, and quite expensive.



Dan



--- On *Fri, 10/8/10, boB Gudgel //* wrote:


From: boB Gudgel 
Subject: Re: [RE-wrenches] Inverter 1741 Listing Process
To: gilliga...@gmail.com, "RE-wrenches"

Date: Friday, October 8, 2010, 9:26 PM

On 10/8/2010 6:04 PM, Matt Lafferty wrote:

Hola Wrenches,
Does anybody know off the top of their head if the
/"5-minute-wait-to-interconnect"/ function is tested on 100% of
inverters produced? /(i.e. every single inverter is tested with
AC & DC within the start parameters of the unit for at least 5
minutes)/
Thanks!
Matt Lafferty


Good question.  I bet it's not 100% tested because if the software
does not
change, then they may just not wait the extra 5 minutes in order
to save money on testing.

Or, maybe they do a random sampling for this test.

Theoretically, it shouldn't matter as long as the software does
not change
and the hardware is tested enough in other ways, like, timers and
clocks etc.

BTW, Nowadays, there are two options for manufacturers of grid
interactive inverters

And the UL spec has gotten more stringent.

One option  is that you have to have  the  code (software) blessed
by the NRTL in a separate process (another UL specification, (UL
1998 --Software in Programmable Components")

OR, if they don't go for that option, then if software changes
need to be done to the inverter, the inverter must (technically)
go through the UL1741 listing process all over again.

boB




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Re: [RE-wrenches] paralleling FM-60's

[boB Gudgel]

On 10/20/2010 12:16 PM, jay peltz wrote:

Hi Jeff,

Its not the voltage but amps, the apollo is only 80amps, and the old 
MX's you can push to 70 so no real advantage there.


j


I think that what he means is that by switching to a 48V battery you can 
have (add)

twice as much array  power rating than you can get from a 24V battery bank,
at a given battery output current.   1500 Watt max array for a 60 Amp 
controller and

24 Volts or  3000 Watts for a 60 Amp controller and 48 Volts.

Or, 4 times the array size if you compare to a 12V battery system by 
going to 48 Volts.


boB






On Oct 20, 2010, at 11:26 AM, Jeff Oldham wrote:

I think you run a very high risk of smoking the controllers. So 
rather than waste the money, gear and potential fire I would suggest 
using either a Apollo HV-80 (200Voc) or the brand new 
Schneider/Xantrex 600Voc controller - the new holy grail of 
controllers! Then rewire the array accordingly.


Good luck!

-jeff o


From the Solar, Wind and Hydro powered office of Jeff 
Oldham/Regenerative SOLutions



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Re: [RE-wrenches] Battery Placement

[boB Gudgel]

On 10/22/2010 10:25 AM, Allan Sindelar wrote:

Ray,
I don't think Robin has posted anything, it just came in a 
conversation we had. As I understand it, service equipment must have 
nothing interfering with designated working clearance, within a few 
inches of depth allowed. With Outback, Magnum, and Xanschneider the 
breakers are on the front surface and are within the allowable depth. 
Midnite/Magnum and Midnite/Outback places them back toward the back 
wall with the inverter on the hinged cover; thus the battery enclosure 
technically sticks out too far. The XW Midnite panel doesn't have this 
issue, as it's a different layout. If necessary, one solution would be 
to mount the E-Panel several inches out from the wall surface.

Allan

*Allan**Sindelar*
al...@positiveenergysolar.com 
NABCEP Certified Photovoltaic Installer
EE98J Journeyman Electrician
*Positive Energy, Inc.*
3201 Calle Marie
Santa Fe, New Mexico 87507
*505 424-1112*
www.positiveenergysolar.com 


On 10/22/2010 10:56 AM, R Ray Walters wrote:

Why does the side mounted breakers make the Midnite non compliant?
Apparently I missed Robin's post on that.
Or do I not want to know?

Thanks,

R. Walters
r...@solarray.com 
Solar Engineer


. Midnite enclosures, with the breakers on the sides, are not 
compliant, as Robin has acknowledged, but it has never been a 
problem for us as the breakers are still easy to access.


*Allan**Sindelar*






Allan, I don't remember saying our equipment is not compliant ?
The battery cabinet cannot obstruct access to the equipment.
The fact that the MidNite breakers are on the side actually
allows better access to servicing them.

The front facing breakers have the connections on the back of
the breaker where you can't see them.  Our breakers are clearly
visible for all the connections compared to all of the alternatives.

The battery boxes stick out 15" from the wall.  This is all the closer
you would be even if there was no battery box under the E-Panel.

Robin




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Re: [RE-wrenches] 120 volt grid tie inverter

[boB Gudgel]

On 11/16/2010 11:20 AM, Richard Scott wrote:
The KACO blueplanet 1502xi inverter has a minimum MPPT voltage of 
125Vdc but cannot be connected to a battery.


I would not recommend hooking a battery up to the input of just any 
grid tie inverter unless it was designed for it.
The current from a battery is significantly higher than that of a PV 
array and can damage the inverter or cause it to fail in a way which 
could be unsafe.


Sincere regards,
Richard Scott
KACO New Energy



One thing that could help to make these kinds of connections work would be
to add a power resistor in series, in-between the inverter input and 
battery.


This will limit the current and make the battery look "more like" a PV 
array.


Of course you will lose some energy in that resistor, but the MPPT algorithm
would have a much better chance of getting it right and current 
limiting  safely.

If it's better than going without, then that's better than nothing.

And, of course, one would have to pick a proper resistance (a few Ohms, 
typically),

and a minimum power rating of the resistor.

boB








On 11/16/2010 10:34 AM, Peter Parrish wrote:

Bob,

So he is grid-tied. But his household loads are all 100 Vdc? I wonder how he
charges his battery bank...If it is PV with a charge controller (or wind),
then I think he can export to the grid and get both a rebate from his
utility and a Federal Tax credit. I assume that he is not interested in
powering the 20 HP motor for his sawmill! If he is charging his batteries
some other way (small hydro) I don't know about the incentives.

But it looks like he is staring at a fully charged battery bank with
generation to spare and is thinking "Why not sell this juice to my utility
company? Fair question. I have no direct experience with the SB700, but it
has been around for eons, and presumably is rock solid and can MPPT at 100 V
all day long. The Fronius inverters only work down to 150 V. The Exeltech
inverters that I am familiar with work down to 200 V. There must be lower
voltage, grid tied inverters out there but the "battery backup" versions
assume 24 Vdc or 48 Vdc battery banks. So, with the exception of the SB700,
there seems to be a gap between 48 V (maybe 60 Vdc) and 150 Vdc.

- Peter

Peter T. Parrish, Ph.D., President
California Solar Engineering, Inc.
820 Cynthia Ave., Los Angeles, CA 90065
CA Lic. 854779, NABCEP Cert. 031806-26
peter.parr...@calsolareng.com
Ph 323-258-8883, Mobile 323-839-6108, Fax 323-258-8885

  


From:re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of bob ellison
Sent: Tuesday, November 16, 2010 5:23 AM
To: 'RE-wrenches'
Subject: Re: [RE-wrenches] 120 volt grid tie inverter

Peter,
The fellow is living with a 120 volt DC battery bank, using it to power his
place and a 20 HP motor on his sawmill.
He wants to reduce the electric bill further than he already has.

So we are looking for an inverter that will take 120 volt DC nominal from
the panels / batteries and send it to the grid.

I am supposed to meet him tomorrow and hope to have more info afterwards.

Thanks,
Bob Ellison

From:re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Peter
Parrish
Sent: Monday, November 15, 2010 8:38 PM
To:glenn.b...@glbcc.com; 'RE-wrenches'
Subject: Re: [RE-wrenches] 120 volt grid tie inverter

Bob,

Do you mean they have a nominal 120 Vdc input? Or do you mean that they want
a 120 Vac (RMS) output? If the former, what output voltage do you want? If
the latter, what is their nominal dc input voltage (better yet the range of
DC input voltages over a range of typical temperatures and irradiance
values)?

- Peter

 
Peter T. Parrish, Ph.D., President

California Solar Engineering, Inc.
820 Cynthia Ave., Los Angeles, CA 90065
CA Lic. 854779, NABCEP Cert. 031806-26
peter.parr...@calsolareng.com  
Ph 323-258-8883, Mobile 323-839-6108, Fax 323-258-8885



-Original Message-
From:re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Glenn Burt
Sent: Monday, November 15, 2010 5:29 PM
To: 'RE-wrenches'
Subject: Re: [RE-wrenches] 120 volt grid tie inverter

I think there is still an SMA 700W inverter available that uses 120VAC.
-Glenn

-Original Message-
From:re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Bob Ellison
Sent: Monday, November 15, 2010 11:14 AM
To: RE-wrenches
Subject: [RE-wrenches] 120 volt grid tie inverter

I have a customer who wants to grid tie a 120 volt dc system
Does anyone know of an inverter that can do this?

Thanks
Bob ellison


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Re: [RE-wrenches] 120 volt grid tie inverter

[boB Gudgel]

On 11/16/2010 1:06 PM, Peter Parrish wrote:

Sure the resistor will limit the current to (100V/R) but it may not be
necessary or even desirable.

One needs to know how the inverter in question works and what it would do
with a very low impedance source (essentially a battery can deliver several
hundred amps at 12 V; let’s say on the order of 50 milli-ohms).

A string of PV modules may present 400V with a short circuit current of 8A
(a source impedance of 50 ohms – a factor of 1000X higher impedance).

This much I know: grid tied inverters start at very high input impedance say
50,000 ohms (drawing very little current) and iterate their way up the “I-V”
curve presenting lower impedances as they go (and checking the power input
at each step). When the most recent step actually decreases the input power,
the MPPT algorithm reverses the step and goes back and forth, constantly
maximizing the input power.

Faced with a source on the order of 50 milli-ohms, the inverter will never
be able to find a maximum power point by lowering its input impedance. So my
question is the following “Will another specification (like maximum out put
power) limit this process and cause the inverter input impedance to sit at
that point which causes a maximum output power?” I doubt that things are
that simple. But the question could be asked of the inverter manufacturer.

One other thing to remember is that inverters have a very large capacitor on
their input which gets charged by the PV string. The capacitor is very much
like a battery (very low impedance) so at least in the beginning of the MMPT
algorithm, an inverter should not have a problem with a battery vs a
capacitor.

Finally, there are relatively simple circuits that can perform “current
limiting” functions and could be used with a battery. Unlike a resistor,
current limiters offer no impedance (to speak of) until the current limit
has been reached and then they do a good job insuring the current set point
is not exceeded. However, they are an “active circuit” and may not be
compatible with a MPPT algorithm.

Sound like someone should spend some time with a “super-tech” at one of the
grid-tied inverter manufacturers and suss this out.

- Peter

Peter T. Parrish, Ph.D., President
California Solar Engineering, Inc.
820 Cynthia Ave., Los Angeles, CA 90065
CA Lic. 854779, NABCEP Cert. 031806-26
peter.parr...@calsolareng.com
Ph 323-258-8883, Mobile 323-839-6108, Fax 323-258-8885





Peter, one of the big problems here is that the inverter (or controller)
expects the Max Power Point Voltage to be so far below the Voc Voltage.
Usually 75% to 80% of the Voc. A battery's MPPV will be around 99% of Voc.

Hard current limiting can keep things from blowing up but won't fix that 
characteristic

without dissipating some power.

Different software can also fix that, as long as the hardware will allow 
it to operate

over this very small Vmpp/Voc ratio.

A resistor is the easiest and quickest way to do that AFAIK. Not the 
best way, just

a quick and dirty way. And even then, it's not quite the same as a PV array.
Just an approximation.

boB







From: re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of boB Gudgel
Sent: Tuesday, November 16, 2010 12:00 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] 120 volt grid tie inverter

On 11/16/2010 11:20 AM, Richard Scott wrote:
The KACO blueplanet 1502xi inverter has a minimum MPPT voltage of 125Vdc but
cannot be connected to a battery.

I would not recommend hooking a battery up to the input of just any grid tie
inverter unless it was designed for it.
The current from a battery is significantly higher than that of a PV array
and can damage the inverter or cause it to fail in a way which could be
unsafe.

Sincere regards,
Richard Scott
KACO New Energy


One thing that could help to make these kinds of connections work would be
to add a power resistor in series, in-between the inverter input and
battery.

This will limit the current and make the battery look "more like" a PV
array.

Of course you will lose some energy in that resistor, but the MPPT algorithm
would have a much better chance of getting it right and current limiting
safely.
If it's better than going without, then that's better than nothing.

And, of course, one would have to pick a proper resistance (a few Ohms,
typically),
and a minimum power rating of the resistor.

boB








On 11/16/2010 10:34 AM, Peter Parrish wrote:
Bob,

So he is grid-tied. But his household loads are all 100 Vdc? I wonder how he
charges his battery bank…If it is PV with a charge controller (or wind),
then I think he can export to the grid and get both a rebate from his
utility and a Federal Tax credit. I assume that he is not interested in
powering the 20 HP motor for his sawmill! If he is charging his batteries
some other way (small hydro) I don’t know about the incentives.

Re: [RE-wrenches] Positive-ground question re Sunpower

[boB Gudgel]

On 11/19/2010 5:22 PM, Glenn Burt wrote:


It has been my experience that if Sunpower modules are installed 
contrary to their manufacturer recommended positive ground 
configuration, that in a short time you will only be generating a few 
watts. I have seen this in more than one instance when the array was 
mis-wired and the negative was the grounded conductor.


Fortunately reversing the wiring allows the static charge to bleed of 
in a couple of weeks, and the strings returned to their expected 
production values.


I would recommend against trying to use them intentionally in this 
fashion.


-Glenn






If you have Sunpower modules that are raised up in the air, what if you 
put a conductive
plate on the back side of the PV module and tie that to positive ??   
(like a Faraday shield)


Does that accomplish the same thing ?   If not, and if you take it 
literally that the
positive must be attached to "earth ground", then I guess this would 
keep Sun Power out

of the solar powered airplane (or space) business.

I  asked Sun Power this question at SPI a couple of years ago and nobody 
could

give me any kind of answer.

boB







*From:*re-wrenches-boun...@lists.re-wrenches.org 
[mailto:re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of 
*Allan Sindelar

*Sent:* Friday, November 19, 2010 10:08 AM
*To:* RE-wrenches
*Subject:* [RE-wrenches] Positive-ground question re Sunpower

Wrenches:
This has been addressed before in a slightly different context, so a 
short answer is enough. Can a Sunpower module be used successfully in 
a negative-grounded low-voltage system?


The situation: Mark in our Taos office sent me the following: "We have 
an old time friend and customer. [John] and his wife used to help us 
on various installations years ago. They're both retired now and 
living on fixed limited income. About two months ago, we sold them a 
replacement battery bank of golf carts. They have a  small off grid 
system with a few hundred watts of PV. Recently, [John's wife] was put 
on an oxygen machine for a heart condition. The machine consumes 
somewhere around 800 Watt-hours per day. Their system can't keep up 
now without running the generator most every day. I was wondering 
about a couple blem/cosmetic damaged panels that PosE has at their 
shop in Santa Fe. I'm not sure yet whether the best solution would be 
to upgrade their existing system, or perhaps a separate system for the 
O2 machine. Either way, if there is a way to help them with the 
equipment, then I'd be happy to donate my time to help [John] do an 
upgrade. If there is some way we can help them out, it would be a good 
thing. They're just a couple of really good people who've helped a lot 
of others out in their lifetime. Now they're the ones in need, and I'm 
just trying to find a way to help them."


We have two Sunpower 215s with cosmetic damage that can't be sold. I 
think that one or both can be used here, but are just somewhat less 
efficient if negative grounded.


What's the straight scoop here, please?
Thanks,
Allan

al...@positiveenergysolar.com 
NABCEP Certified Photovoltaic Installer
EE98J Journeyman Electrician
*Positive Energy, Inc.*
3201 Calle Marie
Santa Fe, New Mexico 87507
*505 424-1112*
www.positiveenergysolar.com 




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Re: [RE-wrenches] Positive-ground question re Sunpower

[boB Gudgel]

On 11/20/2010 4:36 PM, Mark Frye wrote:

From the 2006 white paper:
*

"Polarization

*

Incorrect grounding of SunPower modules can inducea surface charge 
which would lower the energyproduction. Previously SunPower has 
announced the


discovery of the "surface polarization" effect which creates

a non-destructive and reversible accumulation of static

charge on the surface of high-efficiency solar cells such as

SunPower's A-300 cells [9]. When the cells have a high

positive voltage with respect to ground,



How high though ??  I would think that there might be some
curve that might show how high of V produces  how much degradation ?

I assume that the lower voltage modules in the string work better ??

Maybe it's the other way around and the high voltage modules work better
when in a positive grounded system ?


a negative static

charge is built up on the surface of the cell due to current

leakage through the glass and the highly insulating front

surface anti-reflection coating of the cell.



I bet (or hope) that they fix this some day by changing the composition of
the glass, slightly, maybe.

Nobody seems to talk about this except for this one paper that we see.

boB


This negative

static charge causes increased surface recombination and

the performance of the module is reduced. If the polarity

is reversed and the cells are highly negative with respect

to ground, the negative static charge is replaced by a

positive static charge which restores the module

performance."


Mark Frye
Berkeley Solar Electric Systems
303 Redbud Way
Nevada City,  CA 95959
(530) 401-8024
_www.berkeleysolar.com_ 



*From:* re-wrenches-boun...@lists.re-wrenches.org 
[mailto:re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of *jay 
peltz

*Sent:* Saturday, November 20, 2010 4:30 PM
*To:* al...@positiveenergysolar.com; RE-wrenches
*Subject:* Re: [RE-wrenches] Positive-ground question re Sunpower

Hi Allan,

I have seen the white paper from Sunpower, ( but don't have a copy) 
that shows the losses as the voltage rises if using neg ground.


But from memory, if using at low voltages such as two in series there 
should be minimal if any "loss" of watts.
If you could use them as singles, for say a 12v system then there is 
no loss.


Jay

Peltz power


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Re: [RE-wrenches] Roofers installing solar = creative, new installation methods

[boB Gudgel]

On 1/28/2011 8:41 AM, Solar Energy Solutions wrote:

Joel,
Our company cannot survive without selling an entire system.  When we 
help the unqualified and untrained we legitimize unsubstantiated pv 
businesses.  We get  a dozen phone calls a month from folks wanting us 
to install their systems.  It is a rat hole and we have learned that 
not only are such ventures unprofitable, they are fraught with poor 
designs and a plethora of other hassles.  This whole thing reminds me 
of the Carter solar Gold Rush where, sure, a bunch of systems were 
installed, but look at the damage it did to the industry.

Respectfully,





I just hope that the solar installers' industry doesn't have to start 
installing roofs, too !!


boB







*Andrew Koyaanisqatsi*
President
*Solar Energy Solutions, Inc.*
Since 1987,
Moving Portland and Beyond
to an Environmentally Sustainable Future.
*503-238-4502*
*www.solarenergyoregon.com  *
**
*"Better one's House too little one day*
*than too big all the Year after."*


--- On *Fri, 1/28/11, Joel Davidson //* 
wrote:



From: Joel Davidson 
Subject: Re: [RE-wrenches] Roofers installing solar = creative,
new installation methods
To: "RE-wrenches" 
Date: Friday, January 28, 2011, 7:06 AM

Guys,
You're missing a business opportunity. Instead of complaining
about roofers' bad work and competition, show the company owners
photos of their screw-ups and your quality work. Tell him that he
is a risk. Then offer to do their design and electrical
installation (let them do the sales, roofing, and grunt work).
Joel Davidson

- Original Message -
*From:* Warren Lauzon


*To:* RE-wrenches



*Sent:* Friday, January 28, 2011 3:35 AM
*Subject:* Re: [RE-wrenches] Roofers installing solar =
creative,new installation methods

We have seen a lot of the roofing companies nibbling around
the edges of solar installs lately. I have only seen a couple
of installs personally, and they were far from what I would
call professional or reliable. Not quite as bad as your
example, but in one case they had used Romex to run the wiring
down to the inverter, and not in conduit.
*From:* Nick Soleil


*Sent:* Thursday, January 27, 2011 8:11 PM
*To:* re-wrenches@lists.re-wrenches.org



*Subject:* [RE-wrenches] Roofers installing solar =
creative,new installation methods
Hi wrenches:
   Have you noticed that roofing companies have recently been
trying to sell solar?  One company thought of something that I
had never considered.  Listen to this neat story.
   I was servicing a job today, where a roofing company
recently removed and re-installed a PV array on a 12 degree
sloped roof.  The funny thing is that the roofer didn't want
to penetrate his new roof, so he and the customer decided to
leave the panels sitting on the composition roof without any
attachments to the structure.  They didn't think it was
necessary!
Shortly afterward, the array slid down the roof, and a
MultiContact connector came unplugged.  The customer noticed
that his system was not operating, and called us to the site.
Nick Soleil
Project Manager
Advanced Alternative Energy Solutions, LLC
PO Box 657
Petaluma, CA 94953
Cell: 707-321-2937
Office: 707-789-9537
Fax: 707-769-9037



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Re: [RE-wrenches] PV voltage at Isc

[boB Gudgel]

On 2/5/2011 11:30 AM, Greg Egan wrote:

Fellow Scientists,

I got in a discussion with a wrench the other day.  He is under the 
impression that when a PV module is at short circuit current there is 
no voltage.  My understanding of electricity is that if there's no 
voltage there's no current because current needs voltage in order to 
flow.  I'm seeing it as a difference in potential, voltage that is.  
If there's no difference in potential I don't understand why current 
would flow.


I googled it and the few links I checked out were on his side - zero 
voltage at Isc.  All this is of course irrelevant to the business of 
installing PV so if you don't care I don't blame you.


So I still think that if you a precise enough meter that if you stuck 
the test leads into the cables sticking out of the back of a shorted 
PV module that you'd read some small voltage that was approaching 
zero.  Any explanation of why I am right or wrong in plain English 
(I'm not really a scientist) would be welcome.


All the best,

Greg Egan
Remote Power Inc.
Fairbanks, AK


Sorry for the extra response.

Greg, in short, (pun intended),

A short circuit implies just that...  The leads from the PV array or 
module is shorted together.


In a perfect short, there is NO voltage across that short, but full 
current flowing through that short circuit connection.


In an open circuit, there is NO current through the circuit (it's open), 
and full voltage across those two wires.


In-between that short and open somewhere is the max power point 
delivered to the load (inverter, CC, battery, etc)


The load being a partial short.  (or is that a partial open ??)

boB

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Re: [RE-wrenches] module / panel

[boB Gudgel]

On 2/8/2011 3:40 PM, David Brearley wrote:

However, the term "panel" does appear in the NEC in the context of Article
690 "Solar Photovoltaic Systems." (You'll have to submit a proposal to the
Code Making Panel to change the name of the Article, Michael.) Panel is
defined a "collection of modules mechanically fastened together, wired and
designed to provide a field installable unit."

The third photo down in this article shows modules being panelized (bottom
left) and a panel being lifted into position by a crane (top right):

http://solarprofessional.com/article/?file=SP3_4_pg26_Bray&search=




I would say, good luck in trying to change the world's useof these words...

Kind of like the usage of   "Bulk Voltage"vs."Absorb Voltage" 
which we tried

to change years ago at OB.(I'm not totally sure if that worked or not ?)

It's very hard for the majority of users/people to change old habits, 
even if

they are technically incorrect.

I find myself trying very hard to NOT say "solar panel", but to use the 
correct terminology.


Maybe an HP and/or SP article would be good on this and  world will then 
all use

the correct terminology from that point on.

boB






On 2/8/11 5:19 PM, "Michael Welch"  wrote:


FYI, gang (and for what it is worth), Home Power magazine settled on the
following long ago, and it seems consistent with other uses:

A panel can be used to refer to something that captures heat energy, but does
not use the photovoltaic effect. (Like SHW panel, but even SHW "collector" is
what we usually use.)

A single framed set of PV cells with said connecting method is a PV module.
More than one PV module wired together in a set is an array (or a sub-array,
which can also refer to mechanical connection).
All the sub-arrays in a system constitute an array.

Admittedly, there is some arbitrariness in there, but we wanted the magazine
to be consistent.

There is no such thing as a "solar PV" module or panel -- but if there was it
would capture twice the amount of energy due to redundance.

benn kilburn wrote at 02:49 PM 2/8/2011:


Wrenchers,

Which term do you to describe a single framed unit with either a j-box or two
wire leads on the back, module or panel?
Which term do you believe to be correct and why?

My interpretation is that a single framed unit is a module.  Any number of
modules attached to a single detached 'rack' is a panel, and a group of
panels with the same orientation or mounting location/type is an array.

If you agree with my interpretation, what are your thoughts on the widespread
use of the term 'panel' to describe a module.

thanks,
benn

DayStar Renewable Energy Inc.
b...@daystarsolar.ca
780-906-7807
HAVE A SUNNY DAY




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Re: [RE-wrenches] Electromagnetic Pulse (EMP)

[boB Gudgel]

On 3/19/2011 7:53 AM, Drake wrote:

Hello Wrenches,

I had an inquiry concerning the effect of EMP on photovoltaic 
systems.  We are heading for a period of solar activity that likely 
will produce this effect.  According to a local AEP (American Electric 
Power) representative, the utility is spending a lot of money to 
counter this anticipated problem.  Additionally, nuclear related 
issues are moving back to the front burner.


It is clear that the pulse would damage an inverter, but possibly it 
could be put in a Faraday cage.  But a number of questions arise.


* Would the pulse damage the modules?
* Could the large currents and voltages induced by EMP damage the
  conductors in the cells?
* Even if the inverters were surrounded by a Faraday cage, would
  induced currents & voltages from the modules harm the inverters?
  o Would series fuses and surge protectors be adequate
protection.

Has any research been done in this area?  Does anyone know answers to 
any of these questions?


Thanks,

Drake




I don't remember seeing much if any problems during previous 11 year 
cycle solar maximums, really...


Being a ham radio guy, I look forward to solar max and more sunspots...  
HF radio works WAY better during solar maximum !


boB




Drake Chamberlin
Athens Electric
OH License 44810
CO license 3773
NABCEP Certified PV


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Re: [RE-wrenches] Small, non-UL listed direct PV grid-tie inverters and UL 1741

[boB Gudgel]

On 3/26/2011 9:32 AM, Dan Fink wrote:

Mark;

An example:

http://tinyurl.com/4p4367b

and a whole home package! Even includes a Kill-Watt for all your 
energy production monitoring needs:


http://tinyurl.com/4qgogt9


And for an added bonus if you read now, one for a direct grid tie wind 
turbine inverter that takes 3-phase input!


http://tinyurl.com/47xjske

No mention of programming it to match the turbine's power curveso 
I don't think our friends at SMA with the Windyboy and PowerOne with 
the Aurora have to worry about much competition on the 
direct-grid-tied wind side.


Dan Fink




At least it doesn't look like anybody is going for these.

And the last link's bid time ended.

boB



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Re: [RE-wrenches] Enphase Inards - Any Guesses?

[boB Gudgel]

On 4/25/2011 8:56 AM, Mark Frye wrote:


Folks,

I have an Enphase D380 micro inverter sitting on my workbench (such as 
it is).


With my ohm meter I can detect continuity between the chasis and the 
AC equipment ground pin, between the chasis and the DC- pin, and 
between the AC equipment ground pin and DC- pin.


My assumption is that each of these three is electrically identical 
and solidly connected inside the inverter. But, I don't know.


The folks at Enphase tech support will not tell me whether or not this 
is true.


Anyone out there have any ideas about this?




I believe those inverters may have internal Ground Fault Protection and 
would connect, at least,
the DC negative to Chassis (earth) ground via a resettable (hopefully 
resettable) fuse.


One could measure this if they knew what they were doing.

Not sure about the AC side continuity.

boB






Mark Frye
Berkeley Solar Electric Systems
303 Redbud Way
Nevada City,  CA 95959
(530) 401-8024
_www.berkeleysolar.com_ 


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Re: [RE-wrenches] PV powered music festival

[boB Gudgel]

On 4/27/2011 3:51 PM, benn kilburn wrote:

Wrenches,
I have been asked about sizing PV systems for a couple different music 
festivals that have been run solely off of generators in the past. 
 The problem i'm having is determining the energy consumption of 
music/stage (amps, speakers, lights, etc...?) loads as well as 
concession.  The organizers have never considered the kwh of 
electricity used and it has never been metered.  I believe the 
attendance of one festival is expected to be in the range of 5000 and 
the other closer to 15000 over the course of a weekend.


Do any of you have any experiences in this area?  How were the loads 
determined?


No doubt that generator back-up will still be needed, to what extent, 
will be determined.  So what we're looking at would be a temporary 
off-grid PV system with generator back-up...


Any suggestions on how to proceed with this one?

benn



You might want to check the guys out from this article from a year or 
two ago.

I think it's just the kind of thing you're looking for.


http://www.prosoundweb.com/photos/category/C17/


Four (4) pacific northwest companies  made some of the products for this 
tour including the mixer board.


boB







DayStar Renewable Energy Inc.
b...@daystarsolar.ca
780-906-7807
HAVE A SUNNY DAY




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Re: [RE-wrenches] PV powered music festival

[boB Gudgel]

On 4/27/2011 4:50 PM, Starlight Solar, Larry Crutcher wrote:

Benn,
I've had requests like this in the past and have found in EVERY case 
the customer has no idea that it will take a 
$$$multi-tens-of-thousands to replace the generator power. If you have 
the estimating experience, throw out a very large ballpark number to 
see if their eyes get wide. You may find that they say, "Really? 
...That much?"And then you're done.


Best Regards,

Larry Crutcher



This is probably true, but just in case, doesn't hurt to ask I suppose.

Also,  I believe it was Aur Beck ataessolar.com/  had a lot to do 
with running

alternative energy for a super bowl half time show concert (or some
big football thang as I remember) a couple of years ago.

He might also have some info, if nothing more than to say to run away
from this.

That other link I sent didn't have anything like 5000 people I have a 
feeling.


boB








General Manager
Starlight Solar Power Systems 
11881 S Fortuna Road, #210
Yuma, AZ 85367

Phone
(928) 342-9103

/powered by *STARLIGHT*/^(TM)

- Original Message -
*From:* benn kilburn 
*To:* Wrenches 
*Sent:* Wednesday, April 27, 2011 3:51 PM
*Subject:* [RE-wrenches] PV powered music festival

Wrenches,
I have been asked about sizing PV systems for a couple different
music festivals that have been run solely off of generators in the
past.  The problem i'm having is determining the energy
consumption of music/stage (amps, speakers, lights, etc...?) loads
as well as concession.  The organizers have never considered the
kwh of electricity used and it has never been metered.  I believe
the attendance of one festival is expected to be in the range of
5000 and the other closer to 15000 over the course of a weekend.

Do any of you have any experiences in this area?  How were the
loads determined?

No doubt that generator back-up will still be needed, to what
extent, will be determined.  So what we're looking at would be a
temporary off-grid PV system with generator back-up...

Any suggestions on how to proceed with this one?

benn

DayStar Renewable Energy Inc.
b...@daystarsolar.ca
780-906-7807
HAVE A SUNNY DAY


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Re: [RE-wrenches] PV powered music festival

[boB Gudgel]

Just as an aside, today's inverters are pretty much a Class D audio 
amplifier anyway.


An inverter  ~could~ actually be used for a subwoofer amplifer in some 
cases.


I've always wanted to have an inverter with an audio jack on it just for 
that and actually

did try that back a Trace Engineering in the lab.  It worked !

Hey Dan, maybe you guys could do that !Great Solar Shuttle info BTW !

boB

May I tweet you to a woofer ?




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Re: [RE-wrenches] 24 volt Battery Bank comparison

[boB Gudgel]

OK, I've been hearing for years now that one battery string is best and 
maybe two but no more should be used.


What is the reason for this fear ???What is the experience with 
multiple strings in parallel ??


If it is because of current sharing of the strings, that shouldn't be an 
insurmountable problem if the wiring is done right.


If it has to do with the possibility of fire, which Darryl mentioned, 
seems that series string fuses could mitigate the possibility of that 
issue, if because of shorted cells, just like PV combiners.


Or maybe it has to do with the trouble of getting into the middle of a 
pile of batteries ?  Use battery boxes ?


The strings are in parallel and so they all get the same voltage, 
theoretically anyway if the connections are good.


I would think that the more strings, the LESS stress on individual 
batteries, not more.  The current in each battery should be less than it 
would be I would think.


So what is the real experience ??

Is a battery balancer the answer ??

Thanks,
boB







On May 31, 2011, at 8:23 PM, "Wayne Irwin" > wrote:


I think the verdict is*12* - Rolls 2-YS-31 2430 AH @ 20 HR (one 
string) and one dry spare in storage is the best case scenario!


Wayne Irwin, EE
Director of Engineering
Pure Energy Solar International Inc.
State Licensed Solar Contractor
License # CVC56695
wa...@pureenergysolar.com 
http://pureenergysolar.com
352 377-6527 Office
352 336-3299 Fax
352 316-1637 Cell


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Re: [RE-wrenches] 24 volt Battery Bank comparison

[boB Gudgel]

On 5/31/2011 11:25 PM, Tom Elliot wrote:

Bob,
I totally understand the concern about multiple strings *if the 
strings are connected across the battery bank* as had always been the 
tradition in off-grid installations.  My own experience with such a 
bank in my system  showed why when I had a single cell get to near 
meltdown.  I was lucky to find it.



This might be a good reason for an installer to have one of those FLIR 
(or similar) thermal imager cameras.   They're a bit on the expensive 
side, but could
really be helpful for so many things.   Even just to know if you have 
left a nut loose (under load of course)


boB



Maintenance is another reason, such banks are far more difficult to 
maintain.  But I think those concerns are ameliorated a great deal 
with a buss bar installation and once I did that I never had another 
problem and found the battery bank much easier to maintain because the 
strings no longer had to be right next to each other.  Heck, it would 
be possible to put each series string in its own box for that matter.  
And with the inclusion of string fuses that reduces problems even 
further.
When living with an off-grid system my biggest concern was system 
reliability and redundancy and the idea of a single string failure was 
a big worry which is why I never would consider it.

Tom
*From:* boB Gudgel <mailto:b...@midnitesolar.com>
*Sent:* Tuesday, May 31, 2011 8:16 PM
*To:* RE-wrenches <mailto:re-wrenches@lists.re-wrenches.org>
*Subject:* Re: [RE-wrenches] 24 volt Battery Bank comparison


OK, I've been hearing for years now that one battery string is best 
and maybe two but no more should be used.


What is the reason for this fear ???What is the experience with 
multiple strings in parallel ??


If it is because of current sharing of the strings, that shouldn't be 
an insurmountable problem if the wiring is done right.


If it has to do with the possibility of fire, which Darryl mentioned, 
seems that series string fuses could mitigate the possibility of that 
issue, if because of shorted cells, just like PV combiners.


Or maybe it has to do with the trouble of getting into the middle of a 
pile of batteries ?  Use battery boxes ?


The strings are in parallel and so they all get the same voltage, 
theoretically anyway if the connections are good.


I would think that the more strings, the LESS stress on individual 
batteries, not more.  The current in each battery should be less than 
it would be I would think.


So what is the real experience ??

Is a battery balancer the answer ??

Thanks,
boB







On May 31, 2011, at 8:23 PM, "Wayne Irwin" <mailto:wa...@pureenergysolar.com>> wrote:


I think the verdict is*12* - Rolls 2-YS-31 2430 AH @ 20 HR (one 
string) and one dry spare in storage is the best case scenario!


Wayne Irwin, EE
Director of Engineering
Pure Energy Solar International Inc.
State Licensed Solar Contractor
License # CVC56695
wa...@pureenergysolar.com <mailto:wa...@pureenergysolar.com>
http://pureenergysolar.com
352 377-6527 Office
352 336-3299 Fax
352 316-1637 Cell



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Re: [RE-wrenches] 24 volt Battery Bank comparison, Why a single string?

[boB Gudgel]

On 6/1/2011 8:41 AM, Larry Crutcher, Starlight Solar Power Systems wrote:

Hi boB,

We know that current will flow through the lowest resistive path. In a 
perfect world, the resistance from end to end of a battery string will 
be identical. Real world conditions show that one or more cells have a 
slightly higher internal resistance. Add to that the imperfect 
terminal crimp, improper torque at battery terminal, and perhaps 
terminal corrosion and we now have paths of differing resistance. The 
parallel strings have an unequal distribution of current and ergo 
undercharged cells. These cells retain a small amount of amorphous 
lead sulphate that, without correction, will begin to crystalize. We 
all know what will happen over time.




The issue of maintenance is a not brainer of course...  i.e. the need to 
add water...


Imperfect crimps would be a problem with a single string of batteries 
too.  If the resistance
is higher in that cell in the one string, then yes, that one string will 
not be working nearly as
hard as the other strings.  Bad workmanship is not an excuse for not 
using multiple strings

as far as I know.


If one string is discharged more than another parallel string, then its 
finishing (ending) Amps
will will certainly happen later than a string that wasn't discharged as 
deep, but if using a
timed Absorb cycle, why does this matter ??   They're all receiving the 
same voltage and
should be treated the same in that case.  Right ??At least for timed 
charging cycles.


As Darryl pointed out, AGMs like to get hot when unbalanced and this is 
definitely what I
have seen.   But that again can happen for a single string rather than 
multiple strings.


One thing that hasn't been mentioned, unless I missed it, is the 
possibility that a shorted
cell in one string can drag down the other strings it is in parallel 
with.   The more strings
in parallel, statistically, there would be more of a chance for that to 
happen.


That would be more of a self discharge issue I would think which isn't good.
boB




Granted, this can be prevented by the proper knowledge and attention 
but I see far too many failures from neglect and/or lack of 
understanding. My experience comes from 10 years of working with 
hundreds of small 12 volt systems with 2 to 6 parallel strings of 
batteries. In our shop we often see 2 to 3 year old battery banks that 
are damaged and I believe this is a contributing factor. It is often 
too late by the time the problem is discovered. So, my opinion is to 
reduce this possibility by decreasing the parallel paths whenever 
possible.


More strings of a given size battery means less stress per string. 
But, if you decrease strings you are normally increasing cell size to 
maintain the capacity so this should not be an issue.


Battery balancing is a great idea. I would like to see an active 
system for shunting current on a string to keep an equal current 
across all strings. I know this is done in the EV business.


Larry Crutcher
Starlight Solar Power Systems
11871 S Fortuna Road, #210
Yuma, AZ 85367

la...@starlightsolar.com <mailto:la...@starlightsolar.com>
(928) 342-9103



On May 31, 2011, at 11:16 PM, boB Gudgel wrote:




OK, I've been hearing for years now that one battery string is best 
and maybe two but no more should be used.


What is the reason for this fear ???What is the experience with 
multiple strings in parallel ??


If it is because of current sharing of the strings, that shouldn't be 
an insurmountable problem if the wiring is done right.


If it has to do with the possibility of fire, which Darryl mentioned, 
seems that series string fuses could mitigate the possibility of that 
issue, if because of shorted cells, just like PV combiners.


Or maybe it has to do with the trouble of getting into the middle of 
a pile of batteries ?  Use battery boxes ?


The strings are in parallel and so they all get the same voltage, 
theoretically anyway if the connections are good.


I would think that the more strings, the LESS stress on individual 
batteries, not more.  The current in each battery should be less than 
it would be I would think.


So what is the real experience ??

Is a battery balancer the answer ??

Thanks,
boB



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Re: [RE-wrenches] 24 volt Battery Bank comparison

[boB Gudgel]

On 6/1/2011 10:43 AM, Michael Welch wrote:

Every now and then I see reference on this list to the need for thermal 
detection. Here is an interesting, inexpensive piece of equipment that could be 
used for finding hot (loose or corroded) connections, hot batteries, hot PV 
cells in modules, and even poorly insulated spots, its original intended 
purpose:

http://www.blackanddecker.com/power-tools/TLD100.aspx

I have one and used it for finding uninsulated spaces, but cannot attest to its 
durability or suitability for the other uses mentioned above.


Yep.  These are very handy indeed !  AND they're cheap !

But these types are quite different from what I was talking about when I 
mentioned the very pricey thermal imagers like FLIRs.
For the single point thermometers like the B&D device, you must run it 
over EVERY single spot that you want to check
for heat.  Batteries, Connections, Cables and each one individually.  
With something like the FLIR you can just hold it
and stand in one place and it will show you where any hot spots (or cold 
spots) are AND give you the temperature.
That is, if the emissivity is close enough, but you can still see if 
something is really hot with the imager.


I just wish they were cheaper !

boB






boB Gudgel wrote at 01:00 AM 6/1/2011:


This might be a good reason for an installer to have one of those FLIR (or 
similar) thermal imager cameras.   They're a bit on the expensive side, but 
could
really be helpful for so many things.   Even just to know if you have left a 
nut loose (under load of course)

boB


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Re: [RE-wrenches] 24 volt Battery Bank comparison

[boB Gudgel]

Nobody mentioned this in this thread, but it occurs to me that the 
answer may be made clearer
by looking at the Voc of each battery string after so many Amp-Hours 
(years) of service.


i.e., disconnect the strings' parallel connection and measure the 
individual string voltage after charging them all the best that can be done.


This would be  making the assumption that the batteries themselves were 
fairly equal capacity and voltage at installation time.


And for whatever reasons, connections, temperatures and everything else 
discussed here, the strings degrade differently.


The older and more worn out batteries should have a lower voltage (Voc) 
than the less worn out strings. Thus, the better strings
may be tending to hold up the worse strings by dumping charge into them 
when the whole bank is discharging,

and wasting energy and battery efficiency.

I guess that just large 2V cells are the answer in this case, if at all 
possible.


Thanks for the help on this question !

boB



On 6/2/2011 10:42 AM, Tom Elliot wrote:
Not surprised at all about the phone company guy.  It was a phone 
company guy who read me the riot act that no one in their right minds 
would ever parallel battery banks the way PV off-grid systems did and 
got me to set up my system with separate strings connected 
independently to buss bars.  The battery engineer I talked to years 
ago at Dynasty not only said the same thing but also said keeping 
strings separate meant individual string distance from the bars became 
irrelevant (given correctly sized wire for each string’s parallel 
connectors).  I had a system with 12 100 amphour strings of paired 12v 
Dynasty AGMs which was rock solid until the day I sold the house.   
The last time I checked the system before the sale no single battery 
varied from any other in the system by more than 1/10 volt and the 
majority were still holding identical voltages.

*From:* d...@foxfire-energy.com <mailto:d...@foxfire-energy.com>
*Sent:* Wednesday, June 01, 2011 4:14 PM
*To:* RE-wrenches <mailto:re-wrenches@lists.re-wrenches.org>
*Subject:* Re: [RE-wrenches] 24 volt Battery Bank comparison
Good thread. Thanks.
In my experience, it all boils down to the customer. I've seen one 
temp. set up with like 12 strings (for a concert). but they were 
recharged and sold individually within a few weeks.. I've also seen a 
single string (Teledyne aircraft batteries) fail in less than a year.. 
they were in a brand new airplane tug that was never charged -- ever. 
(the guy said "I dunno, it just stopped working").
I have one customer who (last I knew) was running 6 strings of mixed 
aged L-16s going on 8 years. Thing is, he's a retired phone company 
dude (Who's missing half of his right hand from using one of those 
pocket pal screwdriver thingys on a key chain in a hot DC rack.. like 
he'd done hundreds of times before.. but that's another tale). But I 
do like his set up.. he has each string set up with it's own fused 
Disco and Trimetric.. Gives him random control over each string. And 
yes, he keeps a very detailed log, and you can bet that when he takes 
a battery out of service, it's done.
Me? for an average bullet proof off grid system, I shoot for a max of 
two strings for 24V systems (for the redundancy), and manually 
reconfigure them every few years. for 48V systems, I shoot for one 
string of two Volt cells.. thinking that if I loose a cell I can still 
operate a 46V system until I get a replacement.
And Yes, as we all know, there are folks out there that really 
shouldn't be allowed to operate a popsicle stick.

db

Dan Brown
Foxfire Energy Corp.
Renewable Energy Systems
(802)-483-2564
www.Foxfire-Energy.com <http://www.Foxfire-Energy.com>
NABCEP #092907-44


 Original Message 
Subject: Re: [RE-wrenches] 24 volt Battery Bank comparison
From: Michael Welch mailto:michael.we...@re-wrenches.org>>
Date: Wed, June 01, 2011 1:43 pm
To: RE-wrenches mailto:re-wrenches@lists.re-wrenches.org>>

Every now and then I see reference on this list to the need for
thermal detection. Here is an interesting, inexpensive piece of
equipment that could be used for finding hot (loose or corroded)
connections, hot batteries, hot PV cells in modules, and even
poorly insulated spots, its original intended purpose:

http://www.blackanddecker.com/power-tools/TLD100.aspx

I have one and used it for finding uninsulated spaces, but cannot
    attest to its durability or suitability for the other uses
mentioned above.


boB Gudgel wrote at 01:00 AM 6/1/2011:

>This might be a good reason for an installer to have one of those
FLIR (or similar) thermal imager cameras.  They're a bit on the
expensive side, but could
>really be helpful for so many things.  Even just to know if you
have left a nut loose (under load of course)

Re: [RE-wrenches] 24 volt Battery Bank comparison

[boB Gudgel]

On 6/2/2011 6:44 PM, d...@foxfire-energy.com wrote:
What I like best about Mark's set up (the retired phone co. dude w/ 
half a hand), is that he can select individual strings at random. he 
can eq an individual string, or top off a few strings and park them. 
he can even run strings of T 105s, or even nicad (individually of 
course) in the same system as L-16s and the like.. he just reprograms 
the chargers (and logs it). I think he got the design from his days in 
the Navy.


So boB, how about a controller that can be user programed to charge 
multiple battery configurations with a soft switch? i.e. Bank A, Bank 
B...? and while you're at it, maybe a multiple string DC box? 
Something with a shunt and a breaker for each string? A four string 
set up would be nice.


I could use 2% of your first million.

db



Well, It's not a bad idea !   I'll forward that question off to Robin.
I have ran into several that use separate and independent battery banks
and switch between them.  I'm not sure why they don't just use those 
L-16 size

2V cells though instead.

But as I mentioned before, I think that a battery balancer device would take
care of  problems with single strings but maybe even parallel strings,
as well as the pesky problem of AGM batteries that like to plump when
you cook 'em !  (I hate when that happens and one battery gets real hot)

Say, maybe a gizmo that goes across each battery (no 2V cells though) to 
keep each
battery in the string at the same voltage.   It would have to be cheap, 
maybe $30.


Great discussion.

boB





Dan Brown
Foxfire Energy Corp.
Renewable Energy Systems
(802)-483-2564
www.Foxfire-Energy.com <http://www.Foxfire-Energy.com>
NABCEP #092907-44




 Original Message 
Subject: Re: [RE-wrenches] 24 volt Battery Bank comparison
From: boB Gudgel mailto:b...@midnitesolar.com>>
Date: Thu, June 02, 2011 8:56 pm
To: RE-wrenches mailto:re-wrenches@lists.re-wrenches.org>>



Nobody mentioned this in this thread, but it occurs to me that the
answer may be made clearer
by looking at the Voc of each battery string after so many
Amp-Hours (years) of service.

i.e., disconnect the strings' parallel connection and measure the
individual string voltage after charging them all the best that
can be done.

This would be  making the assumption that the batteries themselves
were fairly equal capacity and voltage at installation time.

And for whatever reasons, connections, temperatures and everything
else discussed here, the strings degrade differently.

The older and more worn out batteries should have a lower voltage
(Voc) than the less worn out strings. Thus, the better strings
may be tending to hold up the worse strings by dumping charge into
them when the whole bank is discharging,
and wasting energy and battery efficiency.

I guess that just large 2V cells are the answer in this case, if
at all possible.

Thanks for the help on this question !

boB



On 6/2/2011 10:42 AM, Tom Elliot wrote:

Not surprised at all about the phone company guy.  It was a phone
company guy who read me the riot act that no one in their right
minds would ever parallel battery banks the way PV off-grid
systems did and got me to set up my system with separate strings
connected independently to buss bars.  The battery engineer I
talked to years ago at Dynasty not only said the same thing but
also said keeping strings separate meant individual string
distance from the bars became irrelevant (given correctly sized
wire for each string’s parallel connectors).  I had a system with
12 100 amphour strings of paired 12v Dynasty AGMs which was rock
solid until the day I sold the house.   The last time I checked
the system before the sale no single battery varied from any
other in the system by more than 1/10 volt and the majority were
still holding identical voltages.
*From:* d...@foxfire-energy.com <mailto:d...@foxfire-energy.com>
*Sent:* Wednesday, June 01, 2011 4:14 PM
*To:* RE-wrenches <mailto:re-wrenches@lists.re-wrenches.org>
*Subject:* Re: [RE-wrenches] 24 volt Battery Bank comparison
Good thread. Thanks.
In my experience, it all boils down to the customer. I've seen
one temp. set up with like 12 strings (for a concert). but they
were recharged and sold individually within a few weeks.. I've
also seen a single string (Teledyne aircraft batteries) fail in
less than a year.. they were in a brand new airplane tug that was
never charged -- ever. (the guy said "I dunno, it just stopped
working").
I have one customer who (last I knew) was running 6 strings of
mixed aged L-16s going on 8 years. Thing is, he's a retired phone
company dude (Who's missing half of his right hand from using 

Re: [RE-wrenches] how would you measure a partial short circuit

[boB Gudgel]

On 6/30/2011 8:35 PM, Nick Vida wrote:

Hi wrenches.

I had an interesting case today that I have been thinking about since 
it happened. I dont have all the details because the homeownter had to 
leave before I was done with the service call, but here is what I do 
know. SB5000 with 2 strings of 15 modules. String one was 437 vdc, and 
string 2 was 247vdc. I decided to look for a ground fault, and I 
turned off the inverter. I measured for ground faults and found no 
evidence of anything wrong in that regard. As the homeowner was out of 
time and wanted me to go, I re-landed the wires in the dc disco, and 
when I replaced the fuses, I noticed a minor arc when one of the fuses 
was going it. Although I had no time to measure it, I think that there 
might be a partial short circuit, possibly with one complete string 
and some panels of the other string, and the remaining panels on the 
second string. My mind was racing with how I could have measured for a 
partial short circuit without seeing it as an arch. I can imagine such 
a thing on a bigger system being a dramatic electrical event.
needless to say, I cant wait to get back there and go through the 
signal path properly and find out what the electrician did. And of 
course i realized that replacing the fuses in such a questionable 
situation was probably not the best idea.

Do any of you have any thoughts on how one would measure for such a thing?

nick vida




I'd probably use a DC clamp on ammeter.  Clamp on and measure the top 
and bottom current of each string...   What comes in ~should~ come out.


If it's much different on one end vs. the other end of one string, maybe 
that string is conducting around the path somehow.  Remember that
sometimes just turning the clamp around and measuring the opposite 
polarity may measure slightly differently than the opposite polarity and

that zero calibration is usually necessary.

boB
??
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Re: [RE-wrenches] how would you measure a partial short circuit

[boB Gudgel]

On 6/30/2011 10:48 PM, Marv Dargatz wrote:
>
> Come on, Bob.
>
> It’s a ground fault in the array. Just one more example why ungrounded
> arrays are FAR safer.
>


Could also possibly disconnect the arrays at both ends and use a voltmeter
to measure resistance to ground to find it if that's what the problem is.

Or use a current limited supply and measure voltage drops to zoom in on
the problem.

boB




> See ya!
>
> Marv
>
> Director of Technology and Support, North America
>
> *SolarEdge Technologies, Inc.*
>
> Tech Support Mobile: +530.798.6770
>
> Mobile: +530.392.0356
>
> *From:*re-wrenches-boun...@lists.re-wrenches.org
> [mailto:re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of *boB
> Gudgel
> *Sent:* Thursday, June 30, 2011 10:19 PM
> *To:* RE-wrenches
> *Cc:* Nick Vida
> *Subject:* Re: [RE-wrenches] how would you measure a partial short circuit
>
> On 6/30/2011 8:35 PM, Nick Vida wrote:
>
> Hi wrenches.
>
> I had an interesting case today that I have been thinking about since
> it happened. I dont have all the details because the homeownter had to
> leave before I was done with the service call, but here is what I do
> know. SB5000 with 2 strings of 15 modules. String one was 437 vdc, and
> string 2 was 247vdc. I decided to look for a ground fault, and I
> turned off the inverter. I measured for ground faults and found no
> evidence of anything wrong in that regard. As the homeowner was out of
> time and wanted me to go, I re-landed the wires in the dc disco, and
> when I replaced the fuses, I noticed a minor arc when one of the fuses
> was going it. Although I had no time to measure it, I think that there
> might be a partial short circuit, possibly with one complete string
> and some panels of the other string, and the remaining panels on the
> second string. My mind was racing with how I could have measured for a
> partial short circuit without seeing it as an arch. I can imagine such
> a thing on a bigger system being a dramatic electrical event.
> needless to say, I cant wait to get back there and go through the
> signal path properly and find out what the electrician did. And of
> course i realized that replacing the fuses in such a questionable
> situation was probably not the best idea.
> Do any of you have any thoughts on how one would measure for such a thing?
>
> nick vida
>
>
> I'd probably use a DC clamp on ammeter. Clamp on and measure the top
> and bottom current of each string... What comes in ~should~ come out.
>
> If it's much different on one end vs. the other end of one string,
> maybe that string is conducting around the path somehow. Remember that
> sometimes just turning the clamp around and measuring the opposite
> polarity may measure slightly differently than the opposite polarity and
> that zero calibration is usually necessary.
>
> boB
> 鮑勃
>
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Re: [RE-wrenches] how would you measure a partial short circuit

[boB Gudgel]

On 6/30/2011 8:35 PM, Nick Vida wrote:

Hi wrenches.

I had an interesting case today that I have been thinking about since 
it happened. I dont have all the details because the homeownter had to 
leave before I was done with the service call, but here is what I do 
know. SB5000 with 2 strings of 15 modules. String one was 437 vdc, and 
string 2 was 247vdc. I decided to look for a ground fault, and I 
turned off the inverter. I measured for ground faults and found no 
evidence of anything wrong in that regard. As the homeowner was out of 
time and wanted me to go, I re-landed the wires in the dc disco, and 
when I replaced the fuses, I noticed a minor arc when one of the fuses 
was going it. Although I had no time to measure it, I think that there 
might be a partial short circuit, possibly with one complete string 
and some panels of the other string, and the remaining panels on the 
second string. My mind was racing with how I could have measured for a 
partial short circuit without seeing it as an arch. I can imagine such 
a thing on a bigger system being a dramatic electrical event.
needless to say, I cant wait to get back there and go through the 
signal path properly and find out what the electrician did. And of 
course i realized that replacing the fuses in such a questionable 
situation was probably not the best idea.

Do any of you have any thoughts on how one would measure for such a thing?

nick vida



What does this part of your question mean ??

"I noticed a minor arc when one of the fuses was going it."

boB



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Re: [RE-wrenches] how would you measure a partial short circuit

[boB Gudgel]

On 6/30/2011 11:35 PM, boB Gudgel wrote:

On 6/30/2011 8:35 PM, Nick Vida wrote:

Hi wrenches.

I had an interesting case today that I have been thinking about since 
it happened. I dont have all the details because the homeownter had 
to leave before I was done with the service call, but here is what I 
do know. SB5000 with 2 strings of 15 modules. String one was 437 vdc, 
and string 2 was 247vdc. I decided to look for a ground fault, and I 
turned off the inverter. I measured for ground faults and found no 
evidence of anything wrong in that regard. As the homeowner was out 
of time and wanted me to go, I re-landed the wires in the dc disco, 
and when I replaced the fuses, I noticed a minor arc when one of the 
fuses was going it. Although I had no time to measure it, I think 
that there might be a partial short circuit, possibly with one 
complete string and some panels of the other string, and the 
remaining panels on the second string. My mind was racing with how I 
could have measured for a partial short circuit without seeing it as 
an arch. I can imagine such a thing on a bigger system being a 
dramatic electrical event.
needless to say, I cant wait to get back there and go through the 
signal path properly and find out what the electrician did. And of 
course i realized that replacing the fuses in such a questionable 
situation was probably not the best idea.
Do any of you have any thoughts on how one would measure for such a 
thing?


nick vida



What does this part of your question mean ??

"I noticed a minor arc when one of the fuses was going it."



I see what you were saying.   When the fuse was going "IN" ... Into the 
fuse holder.


Could it be that the inverter was connected (but turned off otherwise) 
and it arced as the inverter input capacitors were charging up ?


If so, then the current would die to nothing soon after the fuse was in 
place.  A clamp meter would show

that too.

boB

boB






boB



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Re: [RE-wrenches] how would you measure a partial short circuit

[boB Gudgel]

On 7/1/2011 12:07 AM, boB Gudgel wrote:

On 6/30/2011 11:35 PM, boB Gudgel wrote:

On 6/30/2011 8:35 PM, Nick Vida wrote:

Hi wrenches.

I had an interesting case today that I have been thinking about 
since it happened. I dont have all the details because the 
homeownter had to leave before I was done with the service call, but 
here is what I do know. SB5000 with 2 strings of 15 modules. String 
one was 437 vdc, and string 2 was 247vdc. I decided to look for a 
ground fault, and I turned off the inverter. I measured for ground 
faults and found no evidence of anything wrong in that regard. As 
the homeowner was out of time and wanted me to go, I re-landed the 
wires in the dc disco, and when I replaced the fuses, I noticed a 
minor arc when one of the fuses was going it. Although I had no time 
to measure it, I think that there might be a partial short circuit, 
possibly with one complete string and some panels of the other 
string, and the remaining panels on the second string. My mind was 
racing with how I could have measured for a partial short circuit 
without seeing it as an arch. I can imagine such a thing on a bigger 
system being a dramatic electrical event.
needless to say, I cant wait to get back there and go through the 
signal path properly and find out what the electrician did. And of 
course i realized that replacing the fuses in such a questionable 
situation was probably not the best idea.
Do any of you have any thoughts on how one would measure for such a 
thing?


nick vida



"I noticed a minor arc when one of the fuses was going it."



I see what you were saying.   When the fuse was going "IN" ... Into 
the fuse holder.


Could it be that the inverter was connected (but turned off otherwise) 
and it arced as the inverter input capacitors were charging up ?


If so, then the current would die to nothing soon after the fuse was 
in place.  A clamp meter would show

that too.




ONE more thing on this...   Because the strings were at slightly 
different VOC's, it's possible that the
higher Voc string will  back feed the lower voltage string and you may 
very well see a small arc if the fuse
is connecting the two strings together.   No ground fault needed for 
that to happen.


boB



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Re: [RE-wrenches] how would you measure a partial short circuit

[boB Gudgel]

OK, nevermind...   That'll teach me to respond before I know the 
question even after reading it

more than 3 times.

 For some reason I read the Voc's as being close in voltage as you said 
here, Nick.


But yes, 247V Vs. 437V would certainly cause a back feed !

Must be late.

boB





On 7/1/2011 12:12 AM, boB Gudgel wrote:

On 7/1/2011 12:07 AM, boB Gudgel wrote:

On 6/30/2011 11:35 PM, boB Gudgel wrote:

On 6/30/2011 8:35 PM, Nick Vida wrote:

Hi wrenches.

I had an interesting case today that I have been thinking about 
since it happened. I dont have all the details because the 
homeownter had to leave before I was done with the service call, 
but here is what I do know. SB5000 with 2 strings of 15 modules. 
String one was 437 vdc, and string 2 was 247vdc. I decided to look 
for a ground fault, and I turned off the inverter. I measured for 
ground faults and found no evidence of anything wrong in that 
regard. As the homeowner was out of time and wanted me to go, I 
re-landed the wires in the dc disco, and when I replaced the fuses, 
I noticed a minor arc when one of the fuses was going it. Although 
I had no time to measure it, I think that there might be a partial 
short circuit, possibly with one complete string and some panels of 
the other string, and the remaining panels on the second string. My 
mind was racing with how I could have measured for a partial short 
circuit without seeing it as an arch. I can imagine such a thing on 
a bigger system being a dramatic electrical event.
needless to say, I cant wait to get back there and go through the 
signal path properly and find out what the electrician did. And of 
course i realized that replacing the fuses in such a questionable 
situation was probably not the best idea.
Do any of you have any thoughts on how one would measure for such a 
thing?


nick vida



"I noticed a minor arc when one of the fuses was going it."



I see what you were saying.   When the fuse was going "IN" ... Into 
the fuse holder.


Could it be that the inverter was connected (but turned off 
otherwise) and it arced as the inverter input capacitors were 
charging up ?


If so, then the current would die to nothing soon after the fuse was 
in place.  A clamp meter would show

that too.




ONE more thing on this...   Because the strings were at slightly 
different VOC's, it's possible that the
higher Voc string will  back feed the lower voltage string and you may 
very well see a small arc if the fuse
is connecting the two strings together.   No ground fault needed for 
that to happen.


boB



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Re: [RE-wrenches] how would you measure a partial short circuit

[boB Gudgel]

On 7/1/2011 10:04 AM, Bill Brooks wrote:


Nick,

If your voltage is low and there is no ground fault, either positive 
and negative are connected mid string, bringing the voltage down, or a 
bunch of modules never got connected in series. In either case, the 
Voc difference between the two strings will create a significant 
current flow at open circuit. That is because the two strings are no 
longer at open circuit, they are connected together so they have a 
circuit. You will see significant current flow in those two strings 
even though they are not connect to anything else. This is a function 
of the IV curve. The higher voltage string is generating power in the 
first quadrant (the one everyone sees on spec sheets), and the lower 
voltage string is operating in the 4^th quadrant---the quadrant nobody 
wants to see. This is the region where you take the IV curve from 
where it crosses the voltage access at Voc and proceed into the 
negative current, positive voltage region. Therefore the power 
generated by the higher voltage string is being absorbed in the lower 
voltage string. An IV curve tracer would do a nice job of showing both 
of these curves and then the composite curve is going to look very 
strange.


Bill.



That's what I was going to say, Bill...

Only having two strings means that the series fuse rating will not be 
exceeded
and those fuses won't blow.   So that won't hurt any modules if that's 
all it is.


Maybe there is some junction box that is shorting out more than one 
module ?  Maybe the

modules that are shorted (if that's what it is), are in one row ?

boB






*From:*re-wrenches-boun...@lists.re-wrenches.org 
[mailto:re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of *Nick 
Vida

*Sent:* Friday, July 01, 2011 7:03 AM
*To:* wrenches
*Subject:* [RE-wrenches] how would you measure a partial short circuit

Hi Bob,

thanks for thinking about my question!

I landed the fuses and put the fuses back in (not it- typo) on my sma  
disconnect, and there was an arc across the fuse holder. Seems like it 
could have been closing a short circuit on the bus once the parallel 
connection was made.




Hi Bill,

Although I am not entirely sure there is no ground fault,
I took the conductors off the terminals so they were in free air, and 
measured pos to neg, pos to ground, neg to ground on both strings, and 
all I saw was the taper towards 0 from about 20 vdc, and no steady 
voltage anywhere but pos to negative. That makes me think the voltage 
is in a short circuit somewhere.
I cant yet make any conclusions about the wiring mistake because I had 
no access to the pull box where the different parts of the strings 
were connected to each other and to the home run. I do think there 
might be a short circuit between strings because when the fuse went 
back in there was an arc on the fuse holder as if there was a short 
circuit instead of a simple parallel connection. I guess it might have 
had to do with the 2 different voltages, but there is voltage 
'missing' somewhere.


Thanks for thinking about my question.



Bob,

re: inverter capacitors charging, I havent seen that much of an arc 
with SMA disconnects, and the switch was in the off position, so I 
dont think there was any signal path to any real electronics. I always 
pull my fuses and do not replace them until everything is landed and 
hot and the voltages look proper when I install, and this arc was way 
out of range of normal.


re: backfeeding, I just suspected that too while thinking about your 
responses, and yes the 2 voltages were different by about 200 volts.


Thanks for the thoughts Bob.


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Re: [RE-wrenches] Fwd: Car charging station without grid

[boB Gudgel]

On 7/14/2011 1:43 PM, Allan Sindelar wrote:

Wrenches,
I'm stumped as to the best approach for a customer who wants a 
non-grid-tied, batteryless PV-powered EV charging station. See below, 
from one of our salespeople. Any ideas?

Thank you,
Allan




So, does this car in the car charging station not use batteries ?

If not, what does the charging station charge ?

Is he sure that he just doesn't need a charger for high voltage batteries ?

boB





 Original Message 

Allan:
Monday I sit down with an interesting fellow who sounds like a 
potential good customer (has money and right enviro goals) - in SF.
He brought up the idea of discussing a car charging station for future 
electric car that:


   1. stands alone, no grid connection
   2. no batteries - he pictures his car is home most days - he parks
  it and when the sun shines it gets charged directly

Why that approach?

   1. He is thinking this must be the most efficient conversion, i.e.
  directly without batteries or line loss of electrons to and from
  utility
   2. Wants the car to function independent of dirty fuel/dirty electrons
   3. He assumes less equipment; maybe less cost but the cost is not
  important other than as example for others

Issues I see:

   1. All inverters that can produce the high voltage needed need grid
  power or if off grid need batteries - know of anything stand
  alone available?
   2. Power or voltage fluctuation as panels see more or less sun; ie
  hours of day or clouds, etc - what will be the output from inverter?
   3. Without tieing into grid investment in PVs (both his financial
  and the embodied for manuf.) gets wasted when car fully charged
  or car not home and sunny.
   4. Is total amps output in peak sun even going to meet the charging
  requirements? ie takes 10 days to recharge instead of 4 hours -
  or overly massive system to match rate of charge?

Your thoughts?
Karlis


*Allan Sindelar*
_Allan@positiveenergysolar.com_ 
NABCEP Certified Photovoltaic Installer
NABCEP Certified Technical Sales Professional
New Mexico EE98J Journeyman Electrician
*Positive Energy, Inc.*
3201 Calle Marie
Santa Fe, New Mexico 87507
*505 424-1112*
_www.positiveenergysolar.com_ 


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Re: [RE-wrenches] 1987 NEC

[boB Gudgel]

On 7/19/2011 2:34 PM, David Brearley wrote:
Presumably the latter---added as part of the cycle of revisions 
initiated in 1987.



The array shorting requirement must have gone away near 1993 or 1994 as
I designed an opening and  shorting of the array style GFPD version in
1994 while at Trace Engineering.

It  would have been expensive.

boB










On 7/19/11 3:29 PM, "Hans Frederickson"  wrote:

David,
Thanks for the interesting history on GFPDs. My copy of the 1987
NEC does not have 690-5, and it's not missing any pages. Either my
code book is an incomplete printing or perhaps John Wiles was
referring to a 1987 proposal that didn't make it into the code
until the 1990 NEC.

Regards,
-Hans


*From:* re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of
*David Brearley
*Sent:* Tuesday, July 19, 2011 12:57 PM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] 1987 NEC

Hans,

John Wiles described the evolution of this standard for a Home
Power article that we referenced later in a SolarPro on PV System
Ground Faults:

http://solarprofessional.com/article/?file=SP2_5_pg60_Mync

"As described by John Wiles, program manager for the Institute for
the Energy and the Environment, in the February/ March 2008 Home
Power article "Ground-Fault Protection Is Expanding," Article
690.5 was added to the /NEC/ in 1987. One of Wiles' first projects
in the PV industry was to develop "prototype hardware" to meet the
new /Code/ requirement. "The basic concept (of the original GFPD
prototype)," writes Wiles, "was to insert a 0.5- or 1-amp circuit
breaker in the dc system-bonding conductor." This small circuit
breaker senses any current between the grounded current-carrying
conductor and the grounding system, tripping if current exceeds
the 0.5 A or 1 A rating. By mechanically linking this smaller
breaker to larger capacity breakers that are installed inline with
the ungrounded current-carrying array conductors, it is possible
to detect, interrupt and indicate that a ground fault has
occurred, and to disconnect the fault.

These early GFPDs were manufactured for 48 V or lower PV systems.
According to Wiles, "As higher voltage, utility-interactive PV
inverters became available in the late 1990s, using a 0.5- or
1-amp fuse as the sensing element and the inverter's control
electronics to monitor the fuse was more cost effective." While
the sensing equipment may have changed, in general the role of the
modern GFPD remains the same as it was in 1987:

1. Detect ground faults in PV arrays.
2. Interrupt the fault current.
3. Indicate that a ground fault has occurred.
4. Disconnect the faulted part of the array.

These four GFPD requirements for grounded PV arrays are spelled
out in /NEC/ 690.5(A) and 690.5(B). The former requires
ground-fault detection and interruption (GFDI), which includes the
provision to indicate the presence of a ground fault. The latter
requires that faulted circuits be isolated either by disconnecting
the ungrounded conductors of the faulted circuit or by shutting
down power to the output power circuits of the inverter or charge
controller.

A final GFPD requirement is found in Article 960.5(C), which calls
for a visible warning in the proximity of the ground-fault
indicator. The warning could be an LED, an LCD or both. In
general, the manufacturer provides this electric shock hazard
warning as part of the listed grid-tied inverter or charge
controller. However, where a PV system includes batteries, the
installer must apply a duplicate warning label near the batteries,
stating:

WARNING
ELECTRIC SHOCK HAZARD
IF A GROUND FAULT IS INDICATED, NORMALLY
GROUNDED CONDUCTORS MAY BE UNGROUNDED
AND ENERGIZED


One change in the GFPD requirements introduced in 1987 is that it
is no longer necessary to short-circuit, or "crowbar," the PV
array in the event of a ground fault. This added step had the
effect of reducing the PV array voltage to zero, minimizing shock
hazard. The requirement was dropped in a subsequent /Code/ cycle,
as leaving the array in a short-circuited condition created
several other issues."


If you're a Home Power subscriber, you can access the original
article in the HP archives. If not, it is summarized above.

Best,

David Brearley, Senior Technical Editor
/SolarPro/ magazine
NABCEP Certified PV Installer ^(TM)
david.brear...@solarprofessional.com
Direct: 541.261.6545


On 7/19/11 2:19 PM, "Hans Frederickson"  wrote:

Kent,
I'm not a geezer yet, but thanks to my dad I do have a  copy
of the 1987 NEC. 690-5 (Ground Fault Detecti

Re: [RE-wrenches] UL PV certification?

[boB Gudgel]

This is an interesting observation regarding this that we heard about.
boB


We have a friend from Washington State that also took the UL class. The 
instructor was not a UL employee, but rather a professional installer 
from Florida. His class was ok, but nothing in depth for anyone that 
already has hands on knowledge of installing PV systems. There was one 
very troubling aspect of their training. They had the inverters and 
disconnect switches and all the associated components of a PV system on 
the wall with one exception. When it came to the combiner, it was clear 
that the combiner had been removed from the wall. Written in pencil was 
the word “PV combiner”. When asked, the instructor had to admit that UL 
forced him to remove the MidNite solar combiner because it was ETL 
listed, not UL! Almost all the combiners are ETL listed. I personally do 
not think UL is doing anybody a good service by only discussing UL 
listed components. Stick with the experts in training. You all know who 
they are.


Robin Gudgel

Midnite Solar





On 7/21/2011 6:52 AM, Glenn Burt wrote:


Don’t you have to be a licensed electrician as part of the prereqs to 
sit for the test?


Glenn

*From:*re-wrenches-boun...@lists.re-wrenches.org 
[mailto:re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of 
*d...@foxfire-energy.com

*Sent:* Thursday, July 21, 2011 9:46 AM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] UL PV certification?

I took the UL/NFPA class in Atlantic City last spring... thinking it 
might make another useful tool in the tool box (especially if I could 
get some kind of recognition from UL).. I was not impressed. The 
presentation was ambiguous, confusing and sometimes downright 
misleading. I got more useful information from Bill Nye the Science 
Guy.. and no certification. Beware the Rabbit Hole.


db


Dan Brown
Foxfire Energy Corp.
Renewable Energy Systems
(802)-483-2564
www.Foxfire-Energy.com 
NABCEP #092907-44



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Re: [RE-wrenches] Power Factor (was Efficient step up, down transformers)

[boB Gudgel]

On 7/26/2011 4:42 PM, Joel Davidson wrote:
Power factor less than 1.0 can shorten the life of and damage 
equipment and reduce PV production. We installed a 200 kW PV system on 
a facility with a lot of 3-phase motors and monitored the PV and the 
grid. We measured around 0.7 PF being delivered by the Los Angeles 
Dept of Water & Power. The data was used as evidence by the PV client 
to negotiate compensation for lost power and get better quality power 
at that site and other facilities. Now I always monitor utility power 
on commercial systems for trouble-shooting.


Joel Davidson




That's very interesting...   I would expect   a current-source type grid 
tie inverter would
be very close to PF of 1.0 (if that one WAS a CS type which I would 
think it would be)


Might be because the grid voltage at that facility is really distorted 
because of the loads
you mentioned.  Did you measure the PF of the line from the GT inverter 
itself ?


What kind of inverter system was this ??   A big one of course.

Some GT inverters that are more of a voltage source will supply lower 
power factor

and tend to clean up the dirty voltage waveform.

boB







- Original Message - From: "Exeltech" 
To: "RE-wrenches" 
Sent: Tuesday, July 26, 2011 12:13 PM
Subject: Re: [RE-wrenches] Efficient step up, down transformers


Hello Ray,

Wow.  I could do an another thesis on the topic of
power factor alone...

There's no good way to fully explain this in depth
here .. so all we can do is scratch the surface.


First, a quick review.

Power factor less than 1.0 causes current flow in a load
that's out of phase with the applied voltage.  The actual
power delivered to the load (and thus consumed by the
source, disregarding efficiency for now), would be:
Vac * Iac * COS(theta) .. where theta is the phase angle
differential between the voltage and current (with the
values for V and I in rms).

Though the real power consumed in a reactive circuit
is going to be less than the real power consumed in
an equivalent resistive circuit (by virtue of the
phase angle), the amperage in the reactive circuit
is still whatever is flowing.

Now, to answer your question...

All inverters will operate at a lower efficiency
when connected to a load with lousy power factor
than if connected to a purely resistive load
under similar operating conditions (VA vs. watts).

The actual efficiency reduction will depend also
on whether the low power factor is due to reactive
components (e.g. inductors or capacitors), or
due to a non-linear load, such as a switching power
supply in a computer, microwave oven, etc.

Nonlinear loads present their own issues that I'll
skip for now.  Let's presume reactive...


That said...

The majority of the losses in inverters under
these conditions would be resistive.


Here's why:
Inverters made with power transformers have large
amounts of copper wire, and consequently, wire
resistance.  When connected to a load with a poor
power factor, transformer-based inverters will not
perform as efficiently as they do when connected
to a purely resistive load.

With a very low power-factor load, you could
theoretically be providing the max current from
an inverter at much lower real power output than
it's rated.  This additional loss, when taken
into account at an AC power with low real wattage
output, will make the inverter's efficiency
worse than with a resistive load.  Expect the
efficiency hit to be on the order of 2-5% for
transformer-based inverters (again, depending on
inverter's max wattage rating as well, as this
will impact the wire size used in its construction,
and thus the total wire resistance).

Transformerless inverters don't have this large
mass of wire (thus much lower internal resistance).
Subsequently, they aren't nearly as affected by
low-power-factor loads - but even here, I'd expect
around 0.5-1% efficiency reduction, all other
conditions being equal.


Power factor is deceptively simple .. but is one of
the more complex aspects of power systems and
power equipment design.


Hope this helps.


Dan Lepinski
Sr. Engineer
Exeltech


P.S. Thanks for being a long-time Exeltech customer.
Much appreciated.



--- On Mon, 7/25/11, R Ray Walters  wrote:

From: R Ray Walters 
Subject: Re: [RE-wrenches] Efficient step up, down transformers
To: "RE-wrenches" 
Date: Monday, July 25, 2011, 4:10 PM
Hi Dan;

I agree that a 2000 VA inverter isn't equal to a 2000 watt
unit.

The focus on VA here though was not about looking at the
rating of the inverter, but instead noting that a load with
a high reactive component might draw more energy than a
purely resistive load in a battery based inverter system. AC
watts might be equal, but my understanding (perhaps false?)
is that the inverter efficiency decreases with PF.

SInce you're in the inverter manufacturing biz, perhaps you
could better explain this to the rest of us.

My fundamental question is: how does power factor effect
the efficiency of an inverter?

A better underst

Re: [RE-wrenches] 2 SW inverters on three phase

[boB Gudgel]

Do you just want to charge batteries  and are these regular  120VAC SWs 
??   120/208 ??


If so, you should just be able to connect each  SW from neutral to hot. 
No stacking necessary.


A regular SW stacking cable won't work for delta connections because 
that assumes
the phases are going to be 180 degrees (120/240) and not 120 degrees as  
for 208V delta.


There was a 3 phase version of the SWs which required a separate 3-way 
cable and

different software in the SW itself.

boB




On Thu, Jul 28, 2011 at 12:23 AM, William Miller 
mailto:will...@millersolar.com>> wrote:


Friends:

Is there any way to connect two SW series inverters to two phases
of a three phase generator?  It seems to me that one could connect
three SW inverters with the right stacking cable (or am I
confusing Outback inverters with the hub jumper set properly).

Any input is appreciated.

Thanks,

William

William Miller
Miller Solar
Voice :805-438-5600 
email: will...@millersolar.com 
http://millersolar.com
License No. C-10-773985


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Re: [RE-wrenches] 2 SW inverters on three phase

[boB Gudgel]

On 7/28/2011 12:32 PM, William Miller wrote:

Friends:

First of all, the inverters are PS series, not SW.

Second, I have created a solution:  I can acquire a transformer that 
will connect a primary across two of the 208 generator phases and 
create 120/240 off of the secondary.  This will imbalance the 
generator but the genset is 37 kva so the inverter loads are 
inconsequential.


William





That should work.

I seem to remember that the SW and PS, even when stacked with the cable 
will sync up to the generator
or grid by whatever is presented at its grid or gen input. I think the 
stacking cable only synched up the inverter phase to
be 180 degrees when inverting as well as coordinating the charging 
functions.


Your transformer would certainly keep away the re-synching from 120 
degrees to 180 degrees as Phil was talking about.


Otherwise, some kind of delay-relay might have been necessary until the 
phases got right if 240V loads were on the

PS outputs.

boB




On Thu, Jul 28, 2011 at 12:23 AM, William Miller 
mailto:will...@millersolar.com>> wrote:


Friends:

Is there any way to connect two SW series inverters to two
phases of a three phase generator?  It seems to me that one
could connect three SW inverters with the right stacking cable
(or am I confusing Outback inverters with the hub jumper set
properly).

Any input is appreciated.

Thanks,

William

William Miller
Miller Solar
Voice :805-438-5600 
email: will...@millersolar.com 
http://millersolar.com 
License No. C-10-773985


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William Miller
Miller Solar
Voice :805-438-5600
email: will...@millersolar.com
http://millersolar.com
License No. C-10-773985


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Re: [RE-wrenches] 2 SW inverters on three phase

[boB Gudgel]

On 7/28/2011 12:48 PM, Steve Higgins wrote:

Yea... we called it "Magic Stacking" back in the trace days.



You also used to be able to stack an OutBack FX inverter with an SW/PS 
inverter.


That was really magic !!

boB






Steve Higgins
Sales Application Engineering Mgr
African Business Development Mgr.
Direct 360-631-7120
Outback Power Technologies
5917 195th Street NE Arlington, Washington 98223


*From:* re-wrenches-boun...@lists.re-wrenches.org 
[mailto:re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of *boB 
Gudgel

*Sent:* Thursday, July 28, 2011 10:56 AM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] 2 SW inverters on three phase



Do you just want to charge batteries  and are these regular  120VAC 
SWs ??   120/208 ??


If so, you should just be able to connect each  SW from neutral to 
hot. No stacking necessary.


A regular SW stacking cable won't work for delta connections because 
that assumes
the phases are going to be 180 degrees (120/240) and not 120 degrees 
as  for 208V delta.


There was a 3 phase version of the SWs which required a separate 3-way 
cable and

different software in the SW itself.

boB




On Thu, Jul 28, 2011 at 12:23 AM, William Miller 
mailto:will...@millersolar.com>> wrote:


Friends:

Is there any way to connect two SW series inverters to two phases
of a three phase generator?  It seems to me that one could
connect three SW inverters with the right stacking cable (or am I
confusing Outback inverters with the hub jumper set properly).

Any input is appreciated.

Thanks,

William

William Miller
Miller Solar
Voice :805-438-5600 
email: will...@millersolar.com <mailto:will...@millersolar.com>
http://millersolar.com
<http://millersolar.com/>License No. C-10-773985





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Re: [RE-wrenches] Large, off grid

[boB Gudgel]

On 8/15/2011 6:34 PM, Darryl Thayer wrote:
Hi wrenches, I have been informed off list that my system is not a 
supported configuration, that one phase can be paralelled, but the 
other two can not, one only on each of the other legs.  So unless 
Outback comes back with more info, I was wrong.  (mine still works, it 
was suggested I am very lucky)
I have used the Apollo in different configurations, stacked in single 
phase, but I have not tried 3 phase stacks.  Maybe you could conact 
Apollo.

Darryl




If you mean your system in Minneapolis, that is OK because they are only 
paralleled on the input (grid) side.


You can have as many inverters as you want selling back to the grid 
(even on 3 phase) as you did...  Just can't parallel
their outputs for off grid use when the power goes down.   Each inverter 
CAN drive its own AC branch load

though.

boB







*From:* Darryl Thayer 
*To:* RE-wrenches 
*Cc:* Julie Haugh 
*Sent:* Monday, August 15, 2011 10:43 AM
*Subject:* Re: [RE-wrenches] Large, off grid

Another method is to use the 120 volt VFX 3648, with one master and 14 
slaves. (15 total, 5 in paralled on each leg)  Check this with Outback 
as the 3 phase is different now than it was back in 2003.  The three 
phase was the master generated a square wave and each slave would use 
this to lag either 120 or 240 degrees.  For standalone not grid tie.  
I did a multi inverter on standalone 3 phase.
Also a good source for this might be  Julie Haugh 
mailto:j...@greenhousepc.com>>; She has done a 
lot of work with Outbacks

Darryl

*From:* jay peltz 
*To:* RE-wrenches 
*Sent:* Friday, August 12, 2011 1:02 PM
*Subject:* Re: [RE-wrenches] Large, off grid

Hi Daryl,

You might look at the new Outback 8kw 120/240v

I know that you can connect up to 10 in parallel,  i don't know if you 
can do it 3 phase however.


jay

peltz power






On Aug 12, 2011, at 8:42 AM, penobscotso...@midmaine.com 
 wrote:


> Hello wrenches,
>  We have an opportunity to install a very large (60 kw) off grid system
> in Mexico. It is currently three phase. I do have the option of
> changing out the air conditioners (36 of them) to 120 single phase, but
> it is an added layer of complexity/cost that it would be nice to avoid.
>  The largest off grid system I've done is 21 kw so far, and it was
> single phase and fairly straightforward.
>  Does anyone know of a three phase, off grid inverter than can be
> paralleled for 500 (possibly 450) amps oputput. I am currently dealing
> with three 120 volt lines (2/0) and a neutral, running to a transformer
> to "clean up" the power from the gennie a bit. The client is determined
> to do this as he has spent about $500,000.00 USD in diesel over the
> last 5 years.I would very much like to get that transformer out of the
> picture...
>  I am well versed in the complexities/pitfalls of battery systems this
> large. I'm planning on using the Surrette YS-31series to minimize the
> footprint, as well as use Water Miser caps and install three separate
> deionizing water systems. My issue is the inverters. I have seen a
> Korean inverter, Sunsine (http://www.dongeiecos.com/) that is capable
> of this, but I am not sure I want my first install of this inverter to
> be 3000 miles away
>  Anyone?
>
> Thanks,
> Daryl DeJoy
> NABCEP Certified PV installer
> Penobscot Solar Design
>
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Re: [RE-wrenches] Evergreen goes down

[boB Gudgel]

On 8/18/2011 11:10 AM, Marco Mangelsdorf wrote:


Evergreen Solar, one of the last remaining independent U.S. module 
manufacturers, announced their plan to file for bankruptcy protection 
this week.


Done in by plummeting module pricing no doubt.

I'm sure you all are getting the same kind of solicitation emails that 
I get from mod manufacturers and wholesalers from across the globe 
peddling mods at low, low prices, including Evergreen.


Anyone have any idea what's going to happen to the warranty coverage 
for Evergreen mods?  Will they become unwanted, unwarrantied orphans, 
a la Astropower?


Sad, sad

marco





I'd beware of newer companies offering say,   50 year warranties !

Hopefully NOT the new business model  !

boB





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[RE-wrenches] Louis Valenta / interisland Solar

[boB Gudgel]

I am sad to report that /Louis Valenta of interisland Solar in Hawaii 
has passed away in the last few days.


Louis had a heart attack about a week ago and this is probably related 
to that.


//He was a very good person, friend and also  extremely knowledgeable in 
our industry.

//
We will really miss //Louis./
/
boB

/
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Re: [RE-wrenches] unique battery bank design question

[boB Gudgel]

On 9/3/2011 7:57 PM, Darryl Thayer wrote:
I have had one experiance with equalizers, the batteries be came very 
unequal.  (over time of course)


*From:* R Ray Walters 
*To:* RE-wrenches 
*Sent:* Saturday, September 3, 2011 5:55 PM
*Subject:* Re: [RE-wrenches] unique battery bank design question

Systems I tried years ago with Vanner equalizers, still ended up being 
unequal. I pulled them all years ago. It seems to be about as much a 
problem as not balancing your battery cables so each battery string 
has the same wire resistance,
I know that you couldn't imagine a few amps on 12" of 2/0 making a 
difference, but after 5 years the battery damage is very consistent 
and identifiable.
The only load I would consider tapping would be metering, or maybe a 
low milliamp relay. I wouldn't go over 100 mA, and even then I bet you 
would see some long term imbalance. I've seen imbalances due  to some 
batteries just being closer to a cold outside wall.


R. Walters
r...@solarray.com 
Solar Engineer



Has anyone that has used battery balancers checked the individual 
battery voltages or SG during charge and/or discharge to

see how well the balancers worked ??

Could it be that the batteries themselves were just not quite the same 
age at the start ??


I would think that a decent balancer system that makes things share 
should work pretty well.  Maybe the balancer

itself does a bit of unbalaced charge/discharge ?

boB


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Re: [RE-wrenches] Invert first?

[boB Gudgel]

On 10/2/2011 11:53 AM, d...@foxfire-energy.com wrote:
If it were me (Depending on how big the back up loads are), I'd make 
the array direct grid tie, and then set up a smaller stand alone 
system (At the house) for critical loadsback up.. more like a big 
UPS.. (no DC in)

db

Dan Brown
Foxfire Energy Corp.
Renewable Energy Systems
(802)-483-2564
www.Foxfire-Energy.com 
NABCEP #092907-44





You could also think about using 2 transformers, one on each end, to 
boost the AC to a few thousand volts to
cut losses.  But transformers have losses too.  Might be able to use 
some type of AC coupling as well for

the backup part ??

boB







 Original Message 
Subject: Re: [RE-wrenches] Invert first?
From: Dan Fink mailto:buckvi...@hughes.net>>
Date: Sun, October 02, 2011 12:50 pm
To: RE-wrenches mailto:re-wrenches@lists.re-wrenches.org>>

Hi Eric;

I'll be very interested to hear what others on this list who have far
more experience than me in large systems have to say about this.

But my first thought is, go DC. The new Xantrex XW high voltage MPPT
charge controller will take up to 600 Voc from PV and put it into a
standard battery bank, that roughly puts you realistically at just 30
amps in your DC lines.

How were you planning to invert to AC at the PV array? Enphase
etc? How
do you do battery backup with an Enphase system (I have no idea,
but am
eager to learn from others here)? Any standard islanding grid-tie
inverter will need to be right next to the battery bank.

Dan Fink
Executive Director;
Buckville Energy Consulting
Buckville Publications LLC
NABCEP / IREC / ISPQ accredited Continuing Education Providers
http://www.buckville.com/
i...@buckville.com 
970.672.4342 (voicemail)
970.373.1311 (fax)



Eric Thomas wrote:
> Wrenches,
>
> We are designing a super high end grid-tied w/ battery backup
system for
> a customer. Array will be ~15kW; pole or stand alone structure
mounted;
> 250' from home/batteries. My question is: does it make any sense to
> invert the power at the array and use this ac to make the long
run to
> the batteries THEN connect to a typical battery charger rather
than a dc
> charge controller? Im mostly concerned with huge dc conductors
making
> this run across the property. Havent delved into the specific design
> enough to size said conductors yet, or specify any equipment, but
wanted
> to know if im barking up the wrong tree ir not.
> Thanks for the insight.
>
> Eric Thomas
> Founder
> Solar Epiphany LLC
> NABCEP Certified PV Installer
> WA Electrical Contractor # SOLAREL911NR
>
>
> 
>
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Re: [RE-wrenches] nabcep executive director

[boB Gudgel]

paul wilkins wrote:

congratulations, ezra

Gee... I thought Ezra ~WAS~   already the head of all NAPCEP  ??

Congrats anyhowz, Ezra !

boB





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Re: [RE-wrenches] Solar Boost Controller in Senegal

[boB Gudgel]

Larry Crutcher, Starlight Solar wrote:
If the SB50 is like other Solar Boost products, there is a zener diode 
on the PV input that will open if the voltage exceeds the Voc maximum. 
 The controller will not "burn up" or be fried but you will have to 
replace the diode. Why it has not happened yet on a cool morning is a 
mystery to me.


If that zener is just across the input terminals, then it might just be 
a "tell-tale" diode for warranty claims.  We had those in the Trace 
inverters too to show
when high voltage or reverse polarity was applied to the unit.  If this 
is the case, then you wouldn't need to replace it to keep the unit working.


If this controller has been in service for a season or more, then you 
most likely have nothing to worry about (Rick Cullen may of course 
enlighten us more)...
A lot of times, the parts (MOSFETs), and sometimes the units themselves 
are conservatively rated, voltage wise.  That's probably why it is still 
working.


My X cents worth.
boB






Kindest Reg


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Re: [RE-wrenches] Solar Boost Controller in Senegal

[boB Gudgel]

Wind-sun.com wrote:
Yes, it is a poor design. though you may not have any problems there 
with the heat de-rating of the panels. If the panel temperature gets 
under about 40C you may blow out the input. As long as you have a load 
on the output of the contgroller, it will keep the voltage down, but 
if the output is disconnected the input could go up to full voltage.


Remember that this controller opens up every so often, (8 seconds or 
so?) to check Voc and adjust the MPP-V based on that measurement.


boB




 
Who designed such a system?
 
..

Northern Arizona Wind & Sun - Electricity From The Sun Since 1979
Online Store: http://store.solar-electric.com/
Solar Discussion Forum: http://www.wind-sun.com/ForumVB/
..

- Original Message -
*From:* Walt Ratterman 
*To:* 'RE-wrenches' 
*Sent:* Friday, June 26, 2009 3:22 PM
*Subject:* [RE-wrenches] Solar Boost Controller in Senegal

Hello,

 


I am in a very remote part of Senegal, (near the Guinea  and Mali
borders…) and I have come across some prefabricated “plug and
play” American made systems installed for educational institutions.

 


The systems use two Sharp panels that are 220Watts, 33.6 Voc, 29.2
Vmp, wired in series, using #10AWG home run wire from the panels
back to the charge controller.

 

Charge Controller is a Solar Boost 50. 

 

Batteries are Dekka AGM – two strings of 250AH, 12V batteries. 
(four batteries total).


 


My specific question is about the controller.  This is a 24V in /
24V out charge controller with MPPT.  I have not used this before,
so I am not familiar with the details of operation.

 


The data sheet that I downloaded says that the maximum open
circuit voltage is 57 VDC.  But, this system is hitting the charge
controller with two panels of 33.6 VDC wired in series for
73.2VDC.  So, why is the controller not fried, or what am I seeing
wrong here.  I suppose with the panel temperature being elevated
maybe 35 degrees above 25 degrees and a resulting 17.5% loss,
coupled with some voltage drop, the system may actually be seeing
less than the 57 volts. 

 


But…..isnt this a dangerous way to design a system?  (it will get
cooler here ….)

 


Or am I missing something?

 


What would be the appropriate application here….

 


Sorry, I cant do a lot of internet research from here – limited
download capability on the satellite….

 


Thanks!!

 


Walt

 


*Walt Ratterman*

*SunEnergy Power International***

* *

11 Laurel Lane South Washougal, WA   98671

(360)-837-3680   ▪   fax (360)-837-1315   ▪   Skype  Walt-Mobile

wratter...@sunepi.org    ▪  
www.SunEPI.org 


 

 




__ Information from ESET NOD32 Antivirus, version of virus
signature database 4193 (20090626) __

The message was checked by ESET NOD32 Antivirus.

http://www.eset.com


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Re: [RE-wrenches] Fisher Paykal on a MAGNASINE

[boB Gudgel]

Michael Welch wrote:
According to a document I received from an F-P technician, here is 
what it takes to run their washers on an inverter: I passed this 
document on to the list late last year, so check your attachments 
folder for

Using 120V Alternate Energy Generation.doc

Are There Existing Customers who are Successfully Running a Smart 
Drive Autowasher From An Inverter Supply?


There are many installations where Smart Drive Autowashers are 
successfully operating on an inverter supply. In our experience if the 
following technical criteria are met by an inverter then operation and 
reliability should not be an issue:


RMS Voltage: 120V +/- 10% (up to -20% may still work provided the pump 
outlet hose is not too high i.e. pumping a high head of water)

Frequency: 60 Hz +/- 5%
Peak Voltage: 200V peak - / This is the major point!!!
/Older style inverters can have an rms voltage inside specification 
but do so by having short duration high voltage pulses. The Smart 
Drive treats this high voltage pulse as a voltage transient and clamps 
the voltage above 200V. The electronics are well rated to absorb this 
clamp energy on a transient basis but not 120 times a second (60Hz) 
continuously. If this continuous clamping occurs then it may lead to 
premature failure of the Smart Drive electronics or the Inverter 
electronics.

Power Rating: 2kVA (2,000VA) minimum.


Normally Modified Square Wave inverters provide too LOW of a peak, and 
change with battery voltage. 200V peak would only occur
at a VERY high battery voltage for most MSW inverters you folks would 
normally use, like a DR etc.


boB




While the Smart Drive only consumes about 650W of power maximum, the 
VA rating can exceed 1kVA. Successful installations have a rating of 
2kVA min.



Allan Sindelar wrote at 04:41 PM 7/1/2009:

According to others on this list, the sine wave Magnum won’t run one, 
so I would be very cautious.

Allan

Allan Sindelar
al...@positiveenergysolar.com 
NABCEP Certified Photovoltaic Installer
EE98J Journeyman Electrician
Positive Energy, Inc.
3201 Calle Marie
Santa Fe, New Mexico 87507
505 424-1112
www.positiveenergysolar.com 

*From:* re-wrenches-boun...@lists.re-wrenches.org [ 
mailto:re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of *Dana

*Sent:* Wednesday, July 01, 2009 5:20 PM
*To:* 'RE-wrenches'
*Subject:* [RE-wrenches] Fisher Paykal on a MAGNASINE

Has anyone run a Fisher-Paykal washer on the Magna sine modified sine 
wave 1200 watt inverter? Good to do or not?


Thanks

Dana Orzel



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Re: [RE-wrenches] Inverter AM Interference

[boB Gudgel]

solar...@aol.com wrote:

  This is a brand new 5000 US.  EMT on all dc runs.  The radio is a 
BOSE...and is 27 feet away.  The interference is runs 24/7... so it 
must be AC related.




Does the radio noise go away when you completely disconnect the SMA 
inverter ?


boB

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Re: [RE-wrenches] Inverter AM Interference

[boB Gudgel]

solar...@aol.com wrote:

It disappears when the breaker is thrown.
Pat Redgate

OK, is that the AC breaker or the PV input breaker ?

How about when you throw the PV input breaker (when not MPPTing) ?  Does 
that help ?


i.e.  We know now that it's the inverter's auxiliary power supply, but 
is the signal also getting
out (radiating) through the PV lines ?  It could also come out the PV 
negative so throwing just the PV input

positive breaker, by itself, may not tell the whole story.

If it's coming through the AC line, then a line filter, or running all 
of the AC side wires through

a ferrite toroid may help.

boB






 
In a message dated 7/15/2009 5:11:58 P.M. Pacific Daylight Time, 
b...@midnitesolar.com writes:



> solar...@aol.com wrote:
>
>   This is a brand new 5000 US.  EMT on all dc runs.  The radio is a
> BOSE...and is 27 feet away.  The interference is runs 24/7... so it
> must be AC related.
>

Does the radio noise go away when you completely disconnect the SMA
inverter ?

boB

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Re: [RE-wrenches] Trace non-volatile memory after market

[boB Gudgel]

Allan Sindelar wrote:


Randy,

We have a very clean, very early used takeout SW4024 (serial #255 or 
so) with Rev 1.0 firmware (and a few Rev. 4.01 chipsets to match 
yours). It appears to have worked flawlessly for 15 years (there’s a 
way to tell with the earliest ones). Contact me offlist if interested.


Allan Sindelar

Allan, that unit is so well "Burnt in", you could almost sell it as 
"Mil-Spec" !


boB

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Re: [RE-wrenches] Fwd: Grounding on a glacier??

[boB Gudgel]

Larry Crutcher, Starlight Solar wrote:

Hi Jay,

An interesting quandary indeed.


This is another good example of an application that I was trying to 
grill Sunpower about --- as far as grounding their modules that need to 
be positive grounded
in order to take advantage of their higher efficiencies.   They couldn't 
answer this simple question.  How would you use one in an airplanefor 
instance ?
There are solar powered airplanes (sort  of)   Is a large faraday shield 
enough ?   Sort of like the ground radials that Larry has mentioned.  I 
would
imagine that if you get large enough radials that it ~might~ approach 
being a virtual ground. Works for antennas though.


I like questions like this one.  Sure makes one think a bit.

boB




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Re: [RE-wrenches] Fwd: Grounding on a glacier, SunPower modules

[boB Gudgel]

Larry Crutcher, Starlight Solar wrote:

I meant to type ...NO noticeable loss of power.


Hi Larry   But how do you ~really~ know you weren't losing power 
because of their lower efficiency unless there was
a comparison made ?  :) I'm not sure that I believe it's all that 
much of a problem, either.


But seriously, I think that  what Sunpower ~really~ means is that they 
have a problem with their lower efficiency on high voltage strings.
I don't imagine that an RV installation would be that high of voltage ? 


I would just like Sunpower to explain this all a bit better.

boB







On Jul 23, 2009, at 7:27 PM, Larry Crutcher, Starlight Solar wrote:

I have installed tons of SunPower 90's without any ground connection 
on RV's with noticeable loss of power. I believe the problem only 
occurs when you have a path to ground from the frame.


Larry

On Jul 23, 2009, at 12:58 PM, boB Gudgel wrote:


Larry Crutcher, Starlight Solar wrote:

Hi Jay,

An interesting quandary indeed.


This is another good example of an application that I was trying to 
grill Sunpower about --- as far as grounding their modules that need 
to be positive grounded
in order to take advantage of their higher efficiencies.   They 
couldn't answer this simple question.  How would you use one in an 
airplanefor instance ?
There are solar powered airplanes (sort  of)   Is a large faraday 
shield enough ?   Sort of like the ground radials that Larry has 
mentioned.  I would
imagine that if you get large enough radials that it ~might~ 
approach being a virtual ground. Works for antennas though.


I like questions like this one.  Sure makes one think a bit.

boB




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Re: [RE-wrenches] Fwd: Grounding on a glacier??

[boB Gudgel]

Darryl Thayer wrote:
The reason for grounding to limit the hazards associated with fault conditions.  If a utility source is unintensionally connected to high voltage the pair of wires can be at elevated voltage.  example would be if a 13,000 volt line falls onto a 120 volt line, the 120 volt line can be raised to 13,000 volts, and the victium would be fried.  So we ground such that the 120 line can not get higher than 120 volts above ground. 

The reference to ground is because we are referenced to ground as we stand bare foot and 


Darryl

  


I always heard that grounding was primarily for lightning protection.
boB






--- On Fri, 7/24/09, Todd Cory  wrote:

  

From: Todd Cory 
Subject: Re: [RE-wrenches] Fwd: Grounding on a glacier??
To: "RE-wrenches" 
Date: Friday, July 24, 2009, 10:50 AM



  
  

 
I have heard that

this
requirement (to bond negative to ground) as well as bonding
one of the
AC conductors to ground (neutral wire) was pushed through
by wire
manufactures and unions. The wire manus sell more of their
product and
the electricians get more labor in installing them. I also
agree that
grounding any live conductor actually makes the system less
safe.



When I have traveled over seas, I always try to open the
main panel to
see how things are laid out. They never associate one of
their power
conductors (usually 240 v) to ground.



Todd





Matt Tritt wrote:

  
As long as we're already on the subject, BESIDE the NEC

requiring it,
why is it that we have to bond the ungrounded conductor on
the battery
side of a DC system??? I believe that we are the only
country in the
world that has this requirement. As long as all the system
cabinets,
mounting plates, housings and etc are grounded, what is
gained by
including a battery conductor? I'm not talking about HV
inputs from an
array, just the battery busses.

  


I have been asking this question since forever, and the
only
explanation seems to be the recital of the Code. Obvious
problems can
occur when there is a + grounded piece of equipment in the
mix, since -
well, it's obvious.

  


Matt T




 



 



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Re: [RE-wrenches] Fwd: Grounding on a glacier??

[boB Gudgel]

toddc...@finestplanet.com wrote:
"If neither pole is grounded then both must be treated as potentially 
hot."


_Only with regard to the other hot wire._ If you do not reference one 
conductor to ground than the other one will not present any danger 
unless you are referenced to its mate... as in touching both wires at 
once.


Todd
Except of course, if there is more leakage (capacitive) from one 
ungrounded wire to ground than the other ungrounded wire to
ground.   You may still feel a tingle... The higher the voltage, given 
similar leakage, the higher the tingleage. (is that a real word?)
I am more apprehensive about touching ungrounded and live things 
(although sometimes I do). People have a larger area and

therefore a higher capacitance than birds do.

This applies for AC (mainly) of course.

boB


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Re: [RE-wrenches] CBI circuit breakers

[boB Gudgel]

Kent Osterberg wrote:

Allan,

I've had trouble with breakers opening when they shouldn't.  On an 
array of two strings of Mitsubishi 175s (Isc = 7.9A) I had two 15-A 
breakers open.  Last week, I had a low-power call from a customer with 
three strings of Evergreen 190s (Isc = 7.1A); one 15-A breaker in the 
combiner was open.  Most of my installs are around 3000 ft elevation, 
so the irradiance is possibly a little higher than normal, but not by 
enough that it should be an issue for 15-amp breakers.  If this is a 
wide-spread problem, I'd expect others on this list to have noticed.


Hi Kent,

Could there be a defective module and the breaker is just doing what it 
is supposed to do ??  What is the series fuse rating for those
modules ?  (probably 15A?)   A shorted or defective module would cause 
those other strings to make it trip, if there are enough

parallel strings.   I hope there isn't some kind of intermittent problem...

Was the breaker actually in the "tripped" position or the "off" 
position, since there is a difference?  (tripped of course means

that there is some play in the lever.)

We (and OB) have sold literally over a million (or millions?) of these 
breakers and we just haven't seen any problems.  You have been
using these breakers for years now...   Have you seen problems before 
this ??   I understand that any problems with CBI breakers
have been AC breakers, not DC, and even then, problems have been far and 
few between.


You could test the breakers though...   Just shove, say, 10 Amps through 
one of the questionable breakers and see if it trips after a while.


It seems kind of odd that more than one of these breakers would have 
defectively tripped near the same time ( week ?  day?  week-day?).


There is, I suppose, the possibility that they could all of a sudden 
have started having some kind of problem, but CBI breakers have
had an excellent track record for many years  now.  We haven't heard 
anything from any other customers here at MidNite.


Can't wait to hear what's causing this problem though...  I'm sure it 
will be very interesting !


boB





As others have mentioned, it is important to take precautions to make 
sure that stranded wires are well tightened in these breakers.  I 
tighten, wiggle, re-tighten, and then check again later.  On systems 
where I've had breakers open, loose connections haven't been the issue.


Kent Osterberg
Blue Mountain Solar, Inc.
www.bluemoutainsolar.com 


Allan Sindelar wrote:

I have had no problems to date, Kent. Can you be more specific as to what
problems you have had? 


Allan Sindelar
al...@positiveenergysolar.com
NABCEP Certified Photovoltaic Installer
EE98J Journeyman Electrician
Positive Energy, Inc.
3201 Calle Marie
Santa Fe, New Mexico 87507
505 424-1112
www.positiveenergysolar.com

-Original Message-
Is it just me, or have other wrenches had problems with the CBI circuit 
breakers used in the Outback or Midnite combiner boxes?


Kent Osterberg
Blue Mountain Solar, Inc.
http://www.bluemountainsolar.com/
  



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Re: [RE-wrenches] CBI circuit breakers

[boB Gudgel]

Allan Sindelar wrote:

Dan,
My understanding is that CBI breakers aren't based on a temperature-related
mechanical action, but a "magnetic-hydraulic" function. I recall that this
was marketed (by Outback? Robin?) as superior to thermal-trip mechanisms as
it was not prone to heat-induced nuisance tripping. boB can probably set us
straight here.
  

Yep.   Magnetic-Hydraulic they are indeed

If you connect them up backwards, they don't quench the arc so well.

One thing I seem to remember is that if they are hot, the trip time 
changes somewhat.   That has to do with
the little magnetic piece that floats around inside the hydraulic fluid 
that can change viscosity (slightly) with

temperature.

Taking one of these little babies apart and looking closely at how it is 
constructed can be very educational.  Somewhere, we
have a Mag-Hyd breaker made out of clear plastic which really shows it 
all well.


And Kent  That is very strange that it was in the "off" position...  
I don't suppose..  Nah !  Someone wouldn't have forgotten

to switch it on.?   Nahh  PV Gremlins in the night ?   Nahh. !

boB





Allan Sindelar
al...@positiveenergysolar.com
NABCEP Certified Photovoltaic Installer
EE98J Journeyman Electrician
Positive Energy, Inc.
3201 Calle Marie
Santa Fe, New Mexico 87507
505 424-1112
www.positiveenergysolar.com

-Original Message-
From: re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Exeltech
Sent: Monday, July 27, 2009 11:03 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] CBI circuit breakers


Wrenches,

An assembly of thoughts:

Circuit breakers operate on a bi-metallic temperature-related mechanical
action.  They are rated to hold a specific current at a specific ambient
temperature.  If the ambient temperature exceeds the breaker specification
for a given current, the breaker will open at a lower current than expected.

If breakers mounted on one or both sides of a suspect breaker are themselves
running warm, this can raise the effective ambient temperature for that
adjacent breaker and cause it to open at a current below the trip rating,
especially if it's near its max current spec.

Though crimp connections to stranded wire may be tight in of themselves, how
about the connection between the cable lug and breaker?  Breaker hardware
has torque specs that must be observed.  If it's not torqued properly, it
will run warm at higher current, and transfer some of that heat to the
internal mechanisms of the circuit breaker, which may cause an early trip.

As a test, use a good DVM set to a millivolt DC scale.  With the maximum
current flowing in the circuit, probe across each connection.  Check wire to
lug; lug to breaker stud, and even across the breaker itself.  You should
measure low millivolts at any connection or location - the lower the better.
Several tenths of a volt drop across any two points with maximum current
flowing in the circuit indicates a bad connection.

If you measure what you feel is an excess voltage drop across a circuit
breaker, and the circuit current isn't excessive, try replacing the breaker
with a new one (preferably from a different batch or mfgr, but of an
identical trip rating) and re-measure the voltage drop across the new
breaker.  If both breakers have a substantially similar drop for the same
current, it's likely the first breaker was ok.

Most of you also know the breakers used for PV-side protection must have a
DC voltage rating greater than the VOC rating of all the PV in that circuit.
If a breaker is being used in a circuit that provides more voltage than the
breaker ratings, repeated opening of the breaker will cause damage to the
internal breaker contacts, leading to a premature trip condition.

Once a breaker trips .. it takes fractionally less current the next time it
trips due to stress and wear of the connecting elements inside the breaker.
If a breaker trips often enough, or if the circuit voltage is near (or
above) the breaker rating when it trips .. it damages the breaker contacts
each time the breaker is opened - both "trip" or manual open.  When this
happens, all bets are off as to the current at which the breaker will open
the next time.

Then again .. there's still a possibility the breakers are defective.

Hope this helps.


Dan




  
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Re: [RE-wrenches] CBI circuit breakers

[boB Gudgel]

Nick Lucchese wrote:

Wrenches,

While we're on the subject of CBI breakers does anyone know a sure way 
to distinguish between the AC and DC versions? Depending on the order 
we get our stock from both Outback (or Outback vendors) as well as 
directly from Midnite. It's obvious with Midnite's 150 VDC MNEPV 
stickers but not all of our breakers come from Midnite and not all who 
handle them know or are always successful at keeping them separated. 
As I look at both options in front of me without Midnite's sticker it 
appears quite confusing. Both have identical QA/QZ and QF markings. I 
did just notice that the MNEPV does also contain a little QDC rating 
on one line, is this the sole indicator or is there something else to 
look for when they don't come from Midnite? Even the AC versions we've 
been getting still say "+ for DC" embossed on the side where the MNEPV 
does not.


Thanks for any insight you're willing to share on my breaker 
questions, Nick A Lucchese



Robin Gudgel made the following comment...

The side markings referred to are generic for all of the CBI 13mm wide
breakers. The real distinguishing markings are on the front of the breaker
below the handle. Midnite has a special ETL listing that allows us to mark
the QY series for 150VDC and now the 2 pole for 300VDC. This sticker covers
up the label that says either 125VDC or 120VAC. The markings are on the
front although they use a sine wave marking to depict AC and straight lines
for DC. To make things easier in the future, just use MidNite breakers. That
way if there is no extra label, it must be an AC breaker.







On Jul 28, 2009, at 8:17 PM, Exeltech wrote:



Agreed.  A bad batch is a possibility.  We use breakers by the pallet 
load, including CBI.  We've not seen an issue such as described here, 
but that doesn't exonerate all of their breakers.  You may be using 
entirely different breakers .. or batches.


I deal with UL on a regular basis, and can speak from experience in 
that regard.  As a UL Listed device, all UL does is test breakers to 
ensure they don't trip at current *above* the amperage and time limit 
specified in the Standards.


If you have access to a beefy DC power supply with an adjustable 
current limit, and can set it for slightly below the rated trip 
current for the suspect breakers, you can perform a basic test on the 
breakers and find them innocent .. or guilty.


If not .. contact CBI directly and have them test the breakers.  Like 
any manufacturer .. I'm sure they'd like to know if there's a problem 
with one of their products .. if even a specific batch.


Dan


--- On Tue, 7/28/09, R. Walters  wrote:


From: R. Walters 
Subject: Re: [RE-wrenches] CBI circuit breakers
To: "RE-wrenches" 
Date: Tuesday, July 28, 2009, 9:39 PM

I also had a faulty 15 A breaker on an array with less
than 11 amps short circuit current. It tripped
intermittently maybe 4 or 5 times over a year, so we swapped
it out. Perhaps they had a bad batch?I was going to
test it at the shop, but didn't have a chance yet.

R. WaltersSolarray.comNABCEP #04170442   



On Jul 27, 2009, at 6:04 PM, Kent Osterberg
wrote:

Allan,

I've had trouble with breakers opening when they
shouldn't.  On an array of two strings of
Mitsubishi 175s (Isc = 7.9A) I had two 15-A breakers
open.  Last week, I had a low-power call from a
customer with three strings of Evergreen 190s (Isc = 7.1A);
one 15-A breaker in the combiner was open.  Most of my
installs are around 3000 ft elevation, so the irradiance is
possibly a little higher than normal, but not by enough that
it should be an issue for 15-amp breakers.  If this is
a wide-spread problem, I'd expect others on this list to
have noticed.

 As others have mentioned, it is important to take
precautions to make sure that stranded wires are well
tightened in these breakers.  I tighten, wiggle,
re-tighten, and then check again later.  On systems
where I've had breakers open, loose connections
haven't been the issue.

 Kent Osterberg
 Blue Mountain Solar, Inc.
 www.bluemoutainsolar.com





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Re: [RE-wrenches] Power Factor

[boB Gudgel]

Ron Young wrote:
Ok, so all seem to be in agreement more or less. How do I break it to 
British Columbia Hydro? :-|


I think they must be misunderstanding what they are asking for but the 
question is in the section for PV and on the same line as the total 
output in Kwh of the PV. Power Factor %


It was most likely just  a trick question.

You're gonna fool them, though !   :)


boB





I'll contact them and see where this goes but I don't fully understand 
what power factor is which will make it hard to argue my case. My 
understanding is that it is the difference between what the utility 
supplies to a residence vs. the actual loads being used by that 
residence expressed as a percentage. 

I came across the following course offering by SEI that discusses 
Power Factor with reference to PV:


POWER FACTOR AS IT RELATES TO SOLAR INSTALLATIONS 
Presented By: Michael Smith of Alpine Management Systems 

 

This session will deal with power factor: What is power factor?  What 
causes low power factor?  Why improve 
your power factor? This session will explain the role of power factor 
correction as it applies to solar installations. 
There are currently over 67,000 KVAR installations in 26 countries 
resulting in phenomenal energy savings with 
a corresponding reduction in greenhouse gas emissions. Session 
includes several KVAR installations and the 
resultant savings. 
http://www.solarenergy.org/workshops/docs/industry08_trainingdetails.pdf


Ron

On 30-Jul-09, at 7:43 AM, Wind-sun.com wrote:


There is no such thing as a power factor for DC or for panels.
 
..

Northern Arizona Wind & Sun - Electricity From The Sun Since 1979
Solar Discussion Forum: http://www.wind-sun.com/ForumVB/
..

- Original Message -
*From:* Ron Young 
*To:* RE-wrenches 
*Sent:* Wednesday, July 29, 2009 5:45 PM
*Subject:* [RE-wrenches] Power Factor

Can anyone point me in the direction to find the power factor for
Sanyo HIT N 205 panels? The utility is requesting it on a net
metering interconnection application.  


Ron Young
earthRight Products - Solareagle.com




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Re: [RE-wrenches] Power Factor

[boB Gudgel]

R. Walters wrote:
Power factor expresses the time difference  between voltage peak and 
current peak on each of their sine waves. If both current and voltage 
waves are "in time", (their wave peaks match up) power factor is 1. If 
one is ahead or behind the other, it's not. Think about an electric 
motor: we hit it with a voltage wave, and a fraction of a second 
later, it actually moves, and the current wave happens. There is a 
little lag there. Resistive loads like lights have very little lag, 
and big electric motors coming up to speed can have horrible PF.


This definition of power factor only applies for linear loads with only 
inductance or capacitance (with resistance) and is called "Displacement 
Power Factor (DPF) and you will  see that on some power meters.


For non-linear loads, like battery chargers or computer power supplies 
without PF Correction,  the current waveform (on an O-scope) looks 
nothing like a sine or cosine wave.   The current "spikes up" at the AC 
voltage peaks.  It actually *looks like* it might be in phase, BUT the 
current and the voltage do NOT look the same.  It's non-linear.  Lower 
than 1.0 power factor for sure.


For a grid tie inverter, resistive heater or any load that has a PF of 
1.0,  the current and voltage waveform will both look exactly the same 
AND there will be no phase shift.   They are both linear and all current 
and voltage is in phase at every point in the AC cycle.


So, because of the different ways of specifying PF, it is always best to 
think of Power Factor as being the ratio of real (in phase) power, or VA 
to reactive power (VARS or "Volt Ampere Reactive").   That will work in 
all cases. (Real Vs. Apparent power is the same thing).   Apparent power 
is what you get when you multiply
your RMS meter's Voltage by the RMS current and is called VA Volt 
Amperes)   V x A will be the highest measured number, that is unless the 
PF = 1.0 in which

case both will measure the same.

Some of that measured VA, or apparent power will be "in phase" and is 
the "real" or "true" power.  Some of that VA may be reactive, (inductive 
or capacitive that is) and is the "out of phase" portion.  Capacitive 
and inductive reactance is ALWAYS 90 degrees out of phase in current and 
voltage It's just a matter of how MUCH of your power is 0 degrees 
phase shift and how MUCH of that VA is  + or - 90 degrees out of phase.  
If  ALL of the current is in phase with the voltage, then
the power factor is 1.0.   That is, if you lay them on top of each 
other, they will look the same on an oscilloscope if power factor = 1.0


It can get way more complicated that this too, but that's basically it.  
Feel free to add to this.


boB



power meters.


There is much more to it, with reactance, "real" and "imaginary" 
numbers?!, etc. but basically, we wrenches need to know that everybody 
wants  Power factor to be close to 1.
Obviously there isn't PF on DC, and it is my understanding that most 
inverters can operate at most power factors. 
Not 100% sure, but I think GT inverters would help not hurt the PF 
problem in most situations.


Correct me on any and all of this, Oh fellow wrenches,

R. Walters
Solarray.com
NABCEP # 04170442















On Jul 30, 2009, at 9:19 AM, boB Gudgel wrote:


Ron Young wrote:
Ok, so all seem to be in agreement more or less. How do I break it 
to British Columbia Hydro? :-|


I think they must be misunderstanding what they are asking for but 
the question is in the section for PV and on the same line as the 
total output in Kwh of the PV. Power Factor %


It was most likely just  a trick question.

You're gonna fool them, though !   :)


boB





I'll contact them and see where this goes but I don't fully 
understand what power factor is which will make it hard to argue my 
case. My understanding is that it is the difference between what the 
utility supplies to a residence vs. the actual loads being used by 
that residence expressed as a percentage. 
I came across the following course offering by SEI that discusses 
Power Factor with reference to PV:


POWER FACTOR AS IT RELATES TO SOLAR INSTALLATIONS Presented By: 
Michael Smith of Alpine Management Systems 
 
This session will deal with power factor: What is power factor?  
What causes low power factor?  Why improve your power factor? This 
session will explain the role of power factor correction as it 
applies to solar installations. There are currently over 67,000 KVAR 
installations in 26 countries resulting in phenomenal energy savings 
with a corresponding reduction in greenhouse gas emissions. Session 
includes several KVAR installations and the resultant savings. 
http://www.solarenergy.org/workshops/docs/industry08_trainingdetails.pdf


Ron

On 30-Jul-09, at 7:43 AM, Wind-sun.com wrote:


There is no such thing as a power factor for DC or 

Re: [RE-wrenches] Power Factor

[boB Gudgel]

boB Gudgel wrote:

>>So, because of the different ways of specifying PF, it is always best 
to think of Power Factor as being the ratio of real (in phase) power, or 
VA to reactive power >>(VARS or "Volt Ampere Reactive").   That will 
work in all cases.



OOOps !   See, this can get confusing.   Reverse what I just said  Power 
Factor... " Definition: The ratio of true power to apparent power"  as 
David Brearley had just posted.  Otherwise, that calculation can give 
you an answer that is GREATER than 1.0 and you don't want that !


Had to eat some of my words.  I just wanted to point out that the phase 
shift method was called DPF.   Didn't Ian Woodenden do an article on PF
recently too ?  If not, he or someone probably should in one of the two 
HP magazines.


boB


R. Walters wrote:
Power factor expresses the time difference  between voltage peak and 
current peak on each of their sine waves. If both current and voltage 
waves are "in time", (their wave peaks match up) power factor is 1. 
If one is ahead or behind the other, it's not. Think about an 
electric motor: we hit it with a voltage wave, and a fraction of a 
second later, it actually moves, and the current wave happens. There 
is a little lag there. Resistive loads like lights have very little 
lag, and big electric motors coming up to speed can have horrible PF.


This definition of power factor only applies for linear loads with 
only inductance or capacitance (with resistance) and is called 
"Displacement Power Factor (DPF) and you will  see that on some power 
meters.


For non-linear loads, like battery chargers or computer power supplies 
without PF Correction,  the current waveform (on an O-scope) looks 
nothing like a sine or cosine wave.   The current "spikes up" at the 
AC voltage peaks.  It actually *looks like* it might be in phase, BUT 
the current and the voltage do NOT look the same.  It's non-linear.  
Lower than 1.0 power factor for sure.


For a grid tie inverter, resistive heater or any load that has a PF of 
1.0,  the current and voltage waveform will both look exactly the same 
AND there will be no phase shift.   They are both linear and all 
current and voltage is in phase at every point in the AC cycle.


So, because of the different ways of specifying PF, it is always best 
to think of Power Factor as being the ratio of real (in phase) power, 
or VA to reactive power (VARS or "Volt Ampere Reactive").   That will 
work in all cases. (Real Vs. Apparent power is the same thing).   
Apparent power is what you get when you multiply
your RMS meter's Voltage by the RMS current and is called VA Volt 
Amperes)   V x A will be the highest measured number, that is unless 
the PF = 1.0 in which

case both will measure the same.

Some of that measured VA, or apparent power will be "in phase" and is 
the "real" or "true" power.  Some of that VA may be reactive, 
(inductive or capacitive that is) and is the "out of phase" portion.  
Capacitive and inductive reactance is ALWAYS 90 degrees out of phase 
in current and voltage It's just a matter of how MUCH of your 
power is 0 degrees phase shift and how MUCH of that VA is  + or - 90 
degrees out of phase.  If  ALL of the current is in phase with the 
voltage, then
the power factor is 1.0.   That is, if you lay them on top of each 
other, they will look the same on an oscilloscope if power factor = 1.0


It can get way more complicated that this too, but that's basically 
it.  Feel free to add to this.


boB



power meters.


There is much more to it, with reactance, "real" and "imaginary" 
numbers?!, etc. but basically, we wrenches need to know that 
everybody wants  Power factor to be close to 1.
Obviously there isn't PF on DC, and it is my understanding that most 
inverters can operate at most power factors. Not 100% sure, but I 
think GT inverters would help not hurt the PF problem in most 
situations.


Correct me on any and all of this, Oh fellow wrenches,

R. Walters
Solarray.com
NABCEP # 04170442















On Jul 30, 2009, at 9:19 AM, boB Gudgel wrote:


Ron Young wrote:
Ok, so all seem to be in agreement more or less. How do I break it 
to British Columbia Hydro? :-|


I think they must be misunderstanding what they are asking for but 
the question is in the section for PV and on the same line as the 
total output in Kwh of the PV. Power Factor %


It was most likely just  a trick question.

You're gonna fool them, though !   :)


boB





I'll contact them and see where this goes but I don't fully 
understand what power factor is which will make it hard to argue my 
case. My understanding is that it is the difference between what 
the utility supplies to a residence vs. the actual loads being used 
by that residence expressed as a percentage. I came across the 
following course o

Re: [RE-wrenches] Power Factor

[boB Gudgel]

Matt wrote:

Possibly a PF question, or maybe one for Magnum - boB,

One of the guys at work is (almost) running a 3/4 hp sub pump with a Magna AE 
48. Or rather, he isn't. According to him when he first fired it up, it 
operated the pump just fine. The next time he tried, though. he couldn't even 
get a buzz out of the starter. No workee.
  

Sounds kind of like a "pump is broken or worn out" problem, doesn't it ?

If there is enough ac voltage applied to the pump, the it should do 
~something~, or lights should dim or some
kind of sign should show itself, wouldn't you think ?   Otherwise, I 
would suspect it might be a surge problem.


Is there a pilot light or something ?   Maybe a fuse blew or breaker 
tripped somewhere ?   (when the pump went off?)


Doesn't sound like a PF problem though... However,  since you mention 
it, with loads that are not a 1.0 power factor,
at least for displacement power factor, when reactive phase shift is 
involved, the inverter must be able to "sink" current
from the stored reactive energy as well as be a source to the motor.   
The Magnum does that just fine, as does any other

decent inverter.

Maybe Tony, Eldon or Gary at Magnum has seen this before ?425-353-8833

boB







The inverter runs all the other loads in the house fine, just not the pump. He 
can run the pump directly from a 7 kW generator with no issues.
So, do you think we're looking at a power factor deficit,(I think not), a motor 
starter problem or an inverter issue? I have to admit to being somewhat baffled 
by this one because it ran the pump once, but not after.

Matt T


 boB Gudgel  wrote: 
  

boB Gudgel wrote:

 >>So, because of the different ways of specifying PF, it is always best 
to think of Power Factor as being the ratio of real (in phase) power, or 
VA to reactive power >>(VARS or "Volt Ampere Reactive").   That will 
work in all cases.



OOOps !   See, this can get confusing.   Reverse what I just said  Power 
Factor... " Definition: The ratio of true power to apparent power"  as 
David Brearley had just posted.  Otherwise, that calculation can give 
you an answer that is GREATER than 1.0 and you don't want that !


Had to eat some of my words.  I just wanted to point out that the phase 
shift method was called DPF.   Didn't Ian Woodenden do an article on PF
recently too ?  If not, he or someone probably should in one of the two 
HP magazines.


boB



R. Walters wrote:
  
Power factor expresses the time difference  between voltage peak and 
current peak on each of their sine waves. If both current and voltage 
waves are "in time", (their wave peaks match up) power factor is 1. 
If one is ahead or behind the other, it's not. Think about an 
electric motor: we hit it with a voltage wave, and a fraction of a 
second later, it actually moves, and the current wave happens. There 
is a little lag there. Resistive loads like lights have very little 
lag, and big electric motors coming up to speed can have horrible PF.

This definition of power factor only applies for linear loads with 
only inductance or capacitance (with resistance) and is called 
"Displacement Power Factor (DPF) and you will  see that on some power 
meters.


For non-linear loads, like battery chargers or computer power supplies 
without PF Correction,  the current waveform (on an O-scope) looks 
nothing like a sine or cosine wave.   The current "spikes up" at the 
AC voltage peaks.  It actually *looks like* it might be in phase, BUT 
the current and the voltage do NOT look the same.  It's non-linear.  
Lower than 1.0 power factor for sure.


For a grid tie inverter, resistive heater or any load that has a PF of 
1.0,  the current and voltage waveform will both look exactly the same 
AND there will be no phase shift.   They are both linear and all 
current and voltage is in phase at every point in the AC cycle.


So, because of the different ways of specifying PF, it is always best 
to think of Power Factor as being the ratio of real (in phase) power, 
or VA to reactive power (VARS or "Volt Ampere Reactive").   That will 
work in all cases. (Real Vs. Apparent power is the same thing).   
Apparent power is what you get when you multiply
your RMS meter's Voltage by the RMS current and is called VA Volt 
Amperes)   V x A will be the highest measured number, that is unless 
the PF = 1.0 in which

case both will measure the same.

Some of that measured VA, or apparent power will be "in phase" and is 
the "real" or "true" power.  Some of that VA may be reactive, 
(inductive or capacitive that is) and is the "out of phase" portion.  
Capacitive and inductive reactance is ALWAYS 90 degrees out of phase 
in current and voltage It's just a matter of how MUCH of your 
power is 0 degrees phase shift and how MUCH of that VA

Re: [RE-wrenches] Power Factor

[boB Gudgel]

Matt wrote:

Unh - hunh, but it will run on the generator. If it didn't, I would go for the bad 
starter or motor, but it "seems" like the PF could be an issue??

Matt T
  


Well, an inverter is just (supposed to be) a low impedance Voltage 
Source and the current does whatever it is going to do... And what that 
current - voltage

relationship is, is definitely related to power factor.

Is the generator (which works fine) passing ~through~ the Magnum and out 
to the loads and pump ?  If so, then you know it's not a high
resistance circuit or loose terminal block screw I guess.   If the 
generator goes around the Magnum AE internal relays then I would

suspect a high resistance connection somewhere.

I would measure the voltage at the pump and note what it does when the 
pump is switched on from the inverter.
I bet you a drink, (next time I see you), that the voltage drops to zero 
or at least very low.


boB







 boB Gudgel  wrote: 
  

Matt wrote:


Possibly a PF question, or maybe one for Magnum - boB,

One of the guys at work is (almost) running a 3/4 hp sub pump with a Magna AE 
48. Or rather, he isn't. According to him when he first fired it up, it 
operated the pump just fine. The next time he tried, though. he couldn't even 
get a buzz out of the starter. No workee.
  
  

Sounds kind of like a "pump is broken or worn out" problem, doesn't it ?

If there is enough ac voltage applied to the pump, the it should do 
~something~, or lights should dim or some
kind of sign should show itself, wouldn't you think ?   Otherwise, I 
would suspect it might be a surge problem.


Is there a pilot light or something ?   Maybe a fuse blew or breaker 
tripped somewhere ?   (when the pump went off?)


Doesn't sound like a PF problem though... However,  since you mention 
it, with loads that are not a 1.0 power factor,
at least for displacement power factor, when reactive phase shift is 
involved, the inverter must be able to "sink" current
from the stored reactive energy as well as be a source to the motor.   
The Magnum does that just fine, as does any other

decent inverter.

Maybe Tony, Eldon or Gary at Magnum has seen this before ?425-353-8833

boB








The inverter runs all the other loads in the house fine, just not the pump. He 
can run the pump directly from a 7 kW generator with no issues.
So, do you think we're looking at a power factor deficit,(I think not), a motor 
starter problem or an inverter issue? I have to admit to being somewhat baffled 
by this one because it ran the pump once, but not after.

Matt T


 boB Gudgel  wrote: 
  
  

boB Gudgel wrote:

 >>So, because of the different ways of specifying PF, it is always best 
to think of Power Factor as being the ratio of real (in phase) power, or 
VA to reactive power >>(VARS or "Volt Ampere Reactive").   That will 
work in all cases.



OOOps !   See, this can get confusing.   Reverse what I just said  Power 
Factor... " Definition: The ratio of true power to apparent power"  as 
David Brearley had just posted.  Otherwise, that calculation can give 
you an answer that is GREATER than 1.0 and you don't want that !


Had to eat some of my words.  I just wanted to point out that the phase 
shift method was called DPF.   Didn't Ian Woodenden do an article on PF
recently too ?  If not, he or someone probably should in one of the two 
HP magazines.


boB




R. Walters wrote:
  
  
Power factor expresses the time difference  between voltage peak and 
current peak on each of their sine waves. If both current and voltage 
waves are "in time", (their wave peaks match up) power factor is 1. 
If one is ahead or behind the other, it's not. Think about an 
electric motor: we hit it with a voltage wave, and a fraction of a 
second later, it actually moves, and the current wave happens. There 
is a little lag there. Resistive loads like lights have very little 
lag, and big electric motors coming up to speed can have horrible PF.


This definition of power factor only applies for linear loads with 
only inductance or capacitance (with resistance) and is called 
"Displacement Power Factor (DPF) and you will  see that on some power 
meters.


For non-linear loads, like battery chargers or computer power supplies 
without PF Correction,  the current waveform (on an O-scope) looks 
nothing like a sine or cosine wave.   The current "spikes up" at the 
AC voltage peaks.  It actually *looks like* it might be in phase, BUT 
the current and the voltage do NOT look the same.  It's non-linear.  
Lower than 1.0 power factor for sure.


For a grid tie inverter, resistive heater or any load that has a PF of 
1.0,  the current and voltage waveform will both look exactly the same 
AND there will be no phase shift.   They are both linear and all 
current

Re: [RE-wrenches] Power Factor

[boB Gudgel]

jay peltz wrote:

Hi Matt,

I would try a few things, but its very curious to me that the inverter 
won't even get a try out of the motor.

I've seen plenty of motors not work, but they tried to start.

And given the 7k genny starts it, the 4k inverter should start it too.
I would check the current under load and surge if possible.
Check the battery voltage.
Could be a bad cap on the motor too.

I've got a new meter that measures PF on the way, just for problems 
like this.


jay

peltz power


Shall we try for 4 out of a million plus ??Maybe it's another  
dreaded CBI breaker ?


boB









On Jul 30, 2009, at 4:03 PM, Matt wrote:

Unh - hunh, but it will run on the generator. If it didn't, I would 
go for the bad starter or motor, but it "seems" like the PF could be 
an issue??


Matt T
 boB Gudgel  wrote:

Matt wrote:

Possibly a PF question, or maybe one for Magnum - boB,

One of the guys at work is (almost) running a 3/4 hp sub pump with 
a Magna AE 48. Or rather, he isn't. According to him when he first 
fired it up, it operated the pump just fine. The next time he 
tried, though. he couldn't even get a buzz out of the starter. No 
workee.


Sounds kind of like a "pump is broken or worn out" problem, doesn't 
it ?


If there is enough ac voltage applied to the pump, the it should do
~something~, or lights should dim or some
kind of sign should show itself, wouldn't you think ?   Otherwise, I
would suspect it might be a surge problem.

Is there a pilot light or something ?   Maybe a fuse blew or breaker
tripped somewhere ?   (when the pump went off?)

Doesn't sound like a PF problem though... However,  since you mention
it, with loads that are not a 1.0 power factor,
at least for displacement power factor, when reactive phase shift is
involved, the inverter must be able to "sink" current
from the stored reactive energy as well as be a source to the motor.
The Magnum does that just fine, as does any other
decent inverter.

Maybe Tony, Eldon or Gary at Magnum has seen this before ?
425-353-8833


boB






The inverter runs all the other loads in the house fine, just not 
the pump. He can run the pump directly from a 7 kW generator with 
no issues.
So, do you think we're looking at a power factor deficit,(I think 
not), a motor starter problem or an inverter issue? I have to admit 
to being somewhat baffled by this one because it ran the pump once, 
but not after.


Matt T


 boB Gudgel  wrote:


boB Gudgel wrote:

So, because of the different ways of specifying PF, it is always 
best
to think of Power Factor as being the ratio of real (in phase) 
power, or

VA to reactive power >>(VARS or "Volt Ampere Reactive").   That will
work in all cases.


OOOps !   See, this can get confusing.   Reverse what I just said  
Power
Factor... " Definition: The ratio of true power to apparent 
power"  as

David Brearley had just posted.  Otherwise, that calculation can give
you an answer that is GREATER than 1.0 and you don't want that !

Had to eat some of my words.  I just wanted to point out that the 
phase
shift method was called DPF.   Didn't Ian Woodenden do an article 
on PF
recently too ?  If not, he or someone probably should in one of 
the two

HP magazines.

boB



R. Walters wrote:

Power factor expresses the time difference  between voltage peak 
and
current peak on each of their sine waves. If both current and 
voltage

waves are "in time", (their wave peaks match up) power factor is 1.
If one is ahead or behind the other, it's not. Think about an
electric motor: we hit it with a voltage wave, and a fraction of a
second later, it actually moves, and the current wave happens. 
There

is a little lag there. Resistive loads like lights have very little
lag, and big electric motors coming up to speed can have 
horrible PF.



This definition of power factor only applies for linear loads with
only inductance or capacitance (with resistance) and is called
"Displacement Power Factor (DPF) and you will  see that on some 
power

meters.

For non-linear loads, like battery chargers or computer power 
supplies

without PF Correction,  the current waveform (on an O-scope) looks
nothing like a sine or cosine wave.   The current "spikes up" at the
AC voltage peaks.  It actually *looks like* it might be in phase, 
BUT

the current and the voltage do NOT look the same.  It's non-linear.
Lower than 1.0 power factor for sure.

For a grid tie inverter, resistive heater or any load that has a 
PF of
1.0,  the current and voltage waveform will both look exactly the 
same

AND there will be no phase shift.   They are both linear and all
current and voltage is in phase at every point in the AC cycle.

So, because of the different ways of specifying PF, it is always 
best
to think of Power Factor as being the ratio of real (in phase) 
power,
or VA to r

Re: [RE-wrenches] Starting 3/4 Sub Pump (was Power Factor)

[boB Gudgel]

Allan Sindelar wrote:

Matt and boB,
This is only somewhat relevant, but may help:
A few days ago, on initial bootup of a new system with a Magnum MS4024AE, we
easily ran a 1HP submersible at nearly 500' head plus pressurizing (single
pump system). However, this was a Grundfos SQ, so the soft-start made it
much easier. Steady draw was about 88ADC at 25 VDC, or around 2200 watts. I
had cautioned the client that this combination wasn't certain to work,
although I expected that it would. 


Allan Sindelar
  
H  If this is a submersible pump, how would you really know it 
was trying to start or not ?

Maybe he just can't hear it trying to start, as short as that try might be ?

Yeah, I'd check the current and voltage when trying to start off the 
inverter and also the generator
just for a reference point.   Sounds like a great use of a PF meter 
actually.


boB




al...@positiveenergysolar.com
NABCEP Certified Photovoltaic Installer
EE98J Journeyman Electrician
Positive Energy, Inc.
3201 Calle Marie
Santa Fe, New Mexico 87507
505 424-1112
www.positiveenergysolar.com

-Original Message-
From: re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of boB Gudgel
Sent: Thursday, July 30, 2009 4:45 PM
To: Matt
Cc: RE-wrenches
Subject: Re: [RE-wrenches] Power Factor

Matt wrote:
  

Possibly a PF question, or maybe one for Magnum - boB,

One of the guys at work is (almost) running a 3/4 hp sub pump with a Magna


AE 48. Or rather, he isn't. According to him when he first fired it up, it
operated the pump just fine. The next time he tried, though. he couldn't
even get a buzz out of the starter. No workee.
  
  


Sounds kind of like a "pump is broken or worn out" problem, doesn't it ?

If there is enough ac voltage applied to the pump, the it should do 
~something~, or lights should dim or some
kind of sign should show itself, wouldn't you think ?   Otherwise, I 
would suspect it might be a surge problem.


Is there a pilot light or something ?   Maybe a fuse blew or breaker 
tripped somewhere ?   (when the pump went off?)


Doesn't sound like a PF problem though... However,  since you mention 
it, with loads that are not a 1.0 power factor,
at least for displacement power factor, when reactive phase shift is 
involved, the inverter must be able to "sink" current
from the stored reactive energy as well as be a source to the motor.   
The Magnum does that just fine, as does any other

decent inverter.

Maybe Tony, Eldon or Gary at Magnum has seen this before ?425-353-8833

boB


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Re: [RE-wrenches] Surge protector update?

[boB Gudgel]

North Texas Renewable Energy Inc wrote:

August
I made a service call to a residential PVinstallation several years 
ago that I did not install. The vintage Trace, size I don't recall, 
had quit working. The Delta surge suppressor had actually ruptured 
along it's radial seam, a result I had always heard indicates a surge 
being absorbed.


Do you know if the Delta was placed at the array, or near the inverter 
??Was most likely installed  at the array ?



Thanks,
boB






The inverter went to the nearest authorized repair shop, a marine 
maintenance facility near Houston. The only problem was a cooked 
internal fusible link which was replaced free of charge.

The array was undamaged.
There's no way of knowing how close the lightning strike was but the 
Delta worked as it was intended. It's the only experience I can relate 
first-hand I'm happy to say.

It will be interesting to hear what sort of results you come up with.
Jim Duncan
North Texas Renewable Energy Inc
817.917.0527
nt...@earthlink.net
www.ntrei.com



--- Original Message - From: "August Goers" 
To: "RE-wrenches" 
Sent: Friday, July 31, 2009 9:21 AM
Subject: [RE-wrenches] Surge protector update?



Wrenches -

Anyone have experience with lighning hitting an array with a surge 
protector installed? What happened?


I'm Here's an ad, point number 5 mentions that the surge protectors 
installed in the array combiner box "protects solar modules and 
blocking diodes..."


http://www.citel.us/dc_surge_protection_overview2.html

I'm trying to gather a firm opinion on whether they are a complete 
waste of $$$ and time or not. Good grounding seems I would guess is 
the best protection.


-August
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Re: [RE-wrenches] solid vs stranded AC vs DC

[boB Gudgel]

jay peltz wrote:

Hi Darryl,

But what are the differences and when do they come into play?




Question interruptus and my 2 cents worth, Jay...

Except for REAL long lines, like utility transmission lines, the AC skin 
effect, which is what I think
you might be referring to here, is probably not worth worrying about one 
way or the other.
And, since stranded wires are not normally insulated from each other, 
stranded will act pretty much

just act like one big solid wire for those concerns anyway.

Stranded wire is easier to bend and work with or course for AC or DC, 
which you already knew.


boB





On Jul 31, 2009, at 7:25 PM, Darryl Thayer wrote:



Well there is very slight differences between AC and Dc But this 
difference

is so slight that it has no effect on anything we will do.
Darryl
--- On Fri, 7/31/09, jay peltz  wrote:


From: jay peltz 
Subject: [RE-wrenches] solid vs stranded  AC vs DC
To: "RE-wrenches" 
Date: Friday, July 31, 2009, 7:00 PM
HI All,

I'm trying to understand this wire issue.

Whether or not there is a difference between stranded or
solid wire for DC or AC.

Any takers on this one?

thanks,

jay

peltz power
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Re: [RE-wrenches] Power Factor

[boB Gudgel]

Chris Worcester wrote:

Has he checked the torque on all the battery connections?

Sincerely,

Chris Worcester
Solar Wind Works
NABCEP Certified PV Installer
Phone: 530-582-4503
Fax: 530-582-4603
www.solarwindworks.com
ch...@solarwindworks.com
"Proven Energy Solutions"

  


Also, Evidence of a bad battery connection (or bad inverter) should be 
obvious if the house lights dim

when the pump tries to start.

boB








-Original Message-
From: re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Matt
Sent: Thursday, July 30, 2009 3:25 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] Power Factor

Possibly a PF question, or maybe one for Magnum - boB,

One of the guys at work is (almost) running a 3/4 hp sub pump with a Magna
AE 48. Or rather, he isn't. According to him when he first fired it up, it
operated the pump just fine. The next time he tried, though. he couldn't
even get a buzz out of the starter. No workee.

The inverter runs all the other loads in the house fine, just not the pump.
He can run the pump directly from a 7 kW generator with no issues.
So, do you think we're looking at a power factor deficit,(I think not), a
motor starter problem or an inverter issue? I have to admit to being
somewhat baffled by this one because it ran the pump once, but not after.

Matt T


 boB Gudgel  wrote: 
  

boB Gudgel wrote:

 >>So, because of the different ways of specifying PF, it is always best 
to think of Power Factor as being the ratio of real (in phase) power, or 
VA to reactive power >>(VARS or "Volt Ampere Reactive").   That will 
work in all cases.



OOOps !   See, this can get confusing.   Reverse what I just said  Power 
Factor... " Definition: The ratio of true power to apparent power"  as 
David Brearley had just posted.  Otherwise, that calculation can give 
you an answer that is GREATER than 1.0 and you don't want that !


Had to eat some of my words.  I just wanted to point out that the phase 
shift method was called DPF.   Didn't Ian Woodenden do an article on PF
recently too ?  If not, he or someone probably should in one of the two 
HP magazines.


boB



R. Walters wrote:
  
Power factor expresses the time difference  between voltage peak and 
current peak on each of their sine waves. If both current and voltage 
waves are "in time", (their wave peaks match up) power factor is 1. 
If one is ahead or behind the other, it's not. Think about an 
electric motor: we hit it with a voltage wave, and a fraction of a 
second later, it actually moves, and the current wave happens. There 
is a little lag there. Resistive loads like lights have very little 
lag, and big electric motors coming up to speed can have horrible PF.

This definition of power factor only applies for linear loads with 
only inductance or capacitance (with resistance) and is called 
"Displacement Power Factor (DPF) and you will  see that on some power 
meters.


For non-linear loads, like battery chargers or computer power supplies 
without PF Correction,  the current waveform (on an O-scope) looks 
nothing like a sine or cosine wave.   The current "spikes up" at the 
AC voltage peaks.  It actually *looks like* it might be in phase, BUT 
the current and the voltage do NOT look the same.  It's non-linear.  
Lower than 1.0 power factor for sure.


For a grid tie inverter, resistive heater or any load that has a PF of 
1.0,  the current and voltage waveform will both look exactly the same 
AND there will be no phase shift.   They are both linear and all 
current and voltage is in phase at every point in the AC cycle.


So, because of the different ways of specifying PF, it is always best 
to think of Power Factor as being the ratio of real (in phase) power, 
or VA to reactive power (VARS or "Volt Ampere Reactive").   That will 
work in all cases. (Real Vs. Apparent power is the same thing).   
Apparent power is what you get when you multiply
your RMS meter's Voltage by the RMS current and is called VA Volt 
Amperes)   V x A will be the highest measured number, that is unless 
the PF = 1.0 in which

case both will measure the same.

Some of that measured VA, or apparent power will be "in phase" and is 
the "real" or "true" power.  Some of that VA may be reactive, 
(inductive or capacitive that is) and is the "out of phase" portion.  
Capacitive and inductive reactance is ALWAYS 90 degrees out of phase 
in current and voltage It's just a matter of how MUCH of your 
power is 0 degrees phase shift and how MUCH of that VA is  + or - 90 
degrees out of phase.  If  ALL of the current is in phase with the 
voltage, then
the power factor is 1.0.   That is, if you lay them on top of each 
other, they will look the same on an oscilloscope if power factor = 1.0


It can get way more complicated t

Re: [RE-wrenches] Magnum inverters (not really a power factor issue)

[boB Gudgel]

Larry Crutcher, Starlight Solar wrote:
Hey Matt, 

I sure wish their techie's would get to the bottom of it. I am getting 
gun-shy about selling Magnum and they are about the best available for 
small 12 volt systems. I have spend hours trying to solve the problem. 
My customer is still not a happy camper.


Larry Crutcher
Starlight Solar
(928) 941-1660
Renewable Energy Products, Service and Installation


Can you get someone to look at the voltage and/or current going into 
that pump ??   Scope ?   Meter ?  Even a
power factor meter would have both voltage and current measurements.  
Some even have a mediocre scope built in.

A scope AND a meter is best of course.

Need  stats.  AC an DC side.  AC voltage at the pump and at the inverter.

Must have more information.Yes, it ~could~ be a Magnum inverter 
issue, but need more information other than "it doesn't work"


Does the voltage dip when the pump tries to start ?  What is the maximum 
Ac and DC current ?  Most basic info for troubleshooting.


The inverter manufacturer can probably help somewhat if they have this info.

Just a suggestion here.

boB








On Aug 1, 2009, at 4:28 PM, Matt Tritt wrote:

I took boB's advice and talked to Magnum about the problem. Their 
take on it? "Hmmm, beats me!" I might be paraphrasing, but that's the 
drift. All in all, I'd say that the suggestions from the group are at 
least as good as the one's from the manufacturer.


Matt T

Larry Crutcher, Starlight Solar wrote:
Don't forget, this is a Magnum inverter and Magnum has issues. I 
have  two customers with Magnum problems. One is a washer that will 
work  perfectly on a cheap import inverter; the other has a Vizio TV 
that  works fine on shore power and generator. S...maybe there 
are pumps  and other items that are anti-Magnum.



Larry Crutcher
Starlight Solar
(928) 941-1660
Renewable Energy Products, Service and Installation




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Re: [RE-wrenches] Magnum inverters (not really a power factor issue)

[boB Gudgel]

Darryl Thayer wrote:
Don't know if this will help, but an experiance of mine on starting a large motor, using a battery and inverter.  The motor would not start, or if it did if would quit in 10, or 20 min.  The battery had capacity to run the motor for 5 or 6 hrs to 50% DoD yet the inverter would kick out.  I had reason to beleive the output wave form was bad also.  I solved the problem by greatly increasing the battery size and the cables.  I did not change the inverter at all.  


What I think was happening is the high current draw of the inverter to serve 
the load reduced the battery voltage, but not just the average battery voltage 
but the 60 cycle peak voltage drop/ of the battery.  The load of the inverter 
on the battery is like pulses, my amp clamp shows an AC current on the battery 
leads.  If I had a scope, I would guess the inverter is seeing a fluxuating 
voltage on the battery.  My grandson has a 1 Farad Capacitor in his sterio 
system, perhaps this would fix the problem.  BoB what do you think?
Darryl
  
Try it.  Put it right across the inverter DC terminals if you do try 
it.   Sometimes, higher capacitance can actually make things worse, 
like, raising the peak

DC voltage seen at the inverter terminals due to L-C resonance.

boB





--- On Sat, 8/1/09, boB Gudgel  wrote:

  

From: boB Gudgel 
Subject: Re: [RE-wrenches] Magnum inverters (not really a power factor issue)
To: "RE-wrenches" 
Date: Saturday, August 1, 2009, 6:22 PM
Larry Crutcher, Starlight Solar
wrote:

Hey Matt, 
I sure wish their techie's would get to the bottom of
  

it. I am getting gun-shy about selling Magnum and they are
about the best available for small 12 volt systems. I have
spend hours trying to solve the problem. My customer is
still not a happy camper.


Larry Crutcher
Starlight Solar
(928) 941-1660
Renewable Energy Products, Service and Installation
  

Can you get someone to look at the voltage and/or current
going into that pump ??   Scope
?   Meter ?  Even a
power factor meter would have both voltage and current
measurements.  Some even have a mediocre scope built
in.
A scope AND a meter is best of course.

Need  stats.  AC an DC side.  AC voltage at
the pump and at the inverter.

Must have more information.Yes, it ~could~ be
a Magnum inverter issue, but need more information other
than "it doesn't work"

Does the voltage dip when the pump tries to start ? 
What is the maximum Ac and DC current ?  Most basic

info for troubleshooting.

The inverter manufacturer can probably help somewhat if
they have this info.

Just a suggestion here.

boB







On Aug 1, 2009, at 4:28 PM, Matt Tritt wrote:

  

I took boB's advice and talked to Magnum about the


problem. Their take on it? "Hmmm, beats me!" I might be
paraphrasing, but that's the drift. All in all, I'd say that
the suggestions from the group are at least as good as the
one's from the manufacturer.


Matt T

Larry Crutcher, Starlight Solar wrote:


Don't forget, this is a Magnum inverter and
  

Magnum has issues. I have  two customers with Magnum
problems. One is a washer that will work  perfectly on
a cheap import inverter; the other has a Vizio TV that 
works fine on shore power and generator. S...maybe there

are pumps  and other items that are anti-Magnum.


Larry Crutcher
Starlight Solar
(928) 941-1660
Renewable Energy Products, Service and
  

Installation




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Re: [RE-wrenches] Magnum inverters (not really a power factor issue)

[boB Gudgel]

Matt Tritt wrote:
The next time I'm up there I'll take another tech with me, plenty of 
meters and go through every DC and AC connection (they all looked good 
first time around) to try and get to the bottom of the problem prior 
to taking a harder look at Magnum. I have to say, though, that I have 
heard a couple of comments that tend to suggest that the inverter 
might turn out to be one logical place to look. I like these inverters 
a lot, and I really hope that we find some other issue.
The inverter is always something to look at.  An installer should always 
carry a decent meter, (Fluke or otherwise), and maybe a clamp-Ammeter
with them when trying to troubleshoot. Some Flukes can be set to read 
the minimum and maximum voltage, so that might also help to check surges 
with.


The Magnum inverter might sag for a moment under a load surge, but its 
voltage will regulate back to normal voltage in a second, or 2 or 3...  
So, if it was
a voltage sag, it would be within range again, momentarily and I would 
expect the pump to start again.   What kind of pump is this again ?  Could
it have some kind of lock-out circuit to keep it from burning up or 
something ?





To replay the symptoms, there is no audible or visual (as in motor 
starter noises or dimming light) indication that the pump is 
attempting to do anything other than sit there when inverter voltage 
is connected to it.
I agree that it isn't trying to start. Light dimming you would probably 
see.  But I wouldn't expect you to actually hear
a submersible pump buried deep in the ground ? 

I still haven't heard, Matt, if the generator is connected in the normal 
way and passes ~through~ the Magnum internal relay and output L1 and L2 
or not.
Is there a separate circuit ?  If the generator (which makes the pump 
work) does not pass through the Magnum inverter, then I would suspect a

bad connection after the inverter output, going to the pump wires.

If the generator is running through the inverter when the generator runs 
the pump, then all of that AC wiring would be verified as working fine.


When the genny power is applied, there is a discernable working under 
a load sound from the engine, and the pump works.
These high frequency inverters ~can~ be dead silent, and often are.  A 
generator engine would be a different thing.  If the generator engine
changes when the pump starts, then its output voltage and/or frequency 
is probably changing too ?



I only had the homeowner's lousy dime store anaglog meter to work 
with, but the voltage from the inverter was right on 120 volts per 
leg. When I checked phase to phase I also only got 120 - that's kind 
of weird, but it might simply be the meter.
Well, 120VAC, L1 to neutral and  120VAC L2 to neutral would be 
correct.   240Vac L1 to L2.



All the household loads run flawlessly (but this is a pretty 
fundamental cabin, so the TV and DVD player are the most exotic things 
plugged in. The run to the pump is adequately sized - - - - - in other 
words, it all seems run of the mill, except that the pump only ran 
successfully one time and not on any further attempts. Golly..


The Magnum inverter, although it might not be the fastest surge, has a 
very good waveform. A 3/4 HP pump should be

a piece of cake for it.

Golly is right !


AND Darryl Thayer said:

BoB are you saying that wires that are so fat and really not very long less than 10 feet can have significant inductance?  >>I thought that inductance was from small wires wrapped into coils?  


All cables have inductance.  Even big fat 10 foot battery cables.
We see L-C resonance (from battery cables) all the time when designing 
inverters,
choosing capacitor sizes, etc... This is why you want to keep the positive and 
negative
battery cables as close to each other as possible.  Inductance can also cause 
the sine-wave
waveform to distort under high current loads.


Anyhow I thought the problem was battery internal resistance, and the building of the sine wave from pulses caused the >>problem..  I have seen battery breakers (thermal type) trip at lower current when feeding a pulse load.  To supply a 1000 >>watts it takes and average current of 80 amps at 12 volts, If that is supplied by a repeating half sine wave, it requires >>a peak current of 112 amps.  If the sine wave building pulses have a 50% duty cycle, the current could be as high as 224 >>amps peak.  


There are all sort of weird things that can happen for sure !



In Larry's case the simple inverter that takes only big pulses, the peak current 
for the  1000 watt load is only 80 amps.  >(much easier on the battery.)
Darryl  



A battery can make a great filter,  and it's best when it's REAL close 
(electrically) to the batteries, but battery impedance is
higher at higher ripple frequencies, and the the AC load can reflect 
itself back to the battery so a capacitor is sometimes a good
addition.   There ~should~ be enough capacitance built into the inverter 
itself, BUT, the in

Re: [RE-wrenches] Magnum inverters (not really a power factor issue)

[boB Gudgel]

Darryl Thayer wrote:
The 120 leg to leg, that is strange.  Is it possible the Inverter has an output not split phase?  perhaps 2 phase or 4 phase? giving the phase to neutral a normal value and the phase to phase a weird value?  I do not think thy would build it this way.  

  

Matt said:
"When I checked phase to phase I also only got 120"

OK, Matt, that part passed right through me... H  (60 Hz 
H... too)


boB




--- On Sat, 8/1/09, Matt Tritt  wrote:

  

From: Matt Tritt 
Subject: Re: [RE-wrenches] Magnum inverters (not really a power factor issue)
To: "RE-wrenches" 
Date: Saturday, August 1, 2009, 10:43 PM



  

 
The next time I'm up there I'll take another tech

with me, plenty of
meters and go through every DC and AC connection (they all
looked good
first time around) to try and get to the bottom of the
problem prior to
taking a harder look at Magnum. I have to say, though, that
I have
heard a couple of comments that tend to suggest that the
inverter might
turn out to be one logical place to look. I like these
inverters a lot,
and I really hope that we find some other issue. 




To replay the symptoms, there is no audible or visual (as
in motor
starter noises or dimming light) indication that the pump
is attempting
to do anything other than sit there when inverter voltage
is connected
to it. When the genny power is applied, there is a
discernable working
under a load sound from the engine, and the pump works. I
only had the
homeowner's lousy dime store anaglog meter to work
with, but the
voltage from the inverter was right on 120 volts per leg.
When I
checked phase to phase I also only got 120 - that's
kind of weird, but
it might simply be the meter. All the household loads run
flawlessly
(but this is a pretty fundamental cabin, so the TV and DVD
player are
the most exotic things plugged in. The run to the pump is
adequately
sized - - - - - in other words, it all seems run of the
mill, except
that the pump only ran successfully one time and not on any
further
attempts. Golly..



Matt



boB Gudgel wrote:
Larry
Crutcher, Starlight Solar wrote:
  

  Hey Matt, 


I sure wish their techie's would get to the bottom of
it. I am getting
gun-shy about selling Magnum and they are about the best
available for
small 12 volt systems. I have spend hours trying to solve
the problem.
My customer is still not a happy camper.





Larry Crutcher



Starlight Solar



(928) 941-1660



Renewable Energy Products, Service and Installation


  
  


Can you get someone to look at the voltage and/or current
going into
that pump ??   Scope ?   Meter ? 
Even a
  


power factor meter would have both voltage and current
measurements. 
Some even have a mediocre scope built in.
  


A scope AND a meter is best of course.
  

  


Need  stats.  AC an DC side.  AC voltage at
the pump and at the
inverter.
  

  


Must have more information.Yes, it
~could~ be a Magnum inverter
issue, but need more information other than "it
doesn't work"
  

  

Does the voltage dip when the pump tries to start ? 
What is the

maximum Ac and DC current ?  Most basic info for
troubleshooting.
  

  


The inverter manufacturer can probably help somewhat if
they have this
info.
  

  


Just a suggestion here.
  

  


boB
  

  

  

  

  

  






On Aug 1, 2009, at 4:28 PM, Matt Tritt wrote:





I took boB's advice and
talked to Magnum
about the problem. Their take on it? "Hmmm, beats
me!" I might be
paraphrasing, but that's the drift. All in all, I'd
say that the
suggestions from the group are at least as good as the
one's from the
manufacturer.
  

  


Matt T
  

  


Larry Crutcher, Starlight Solar wrote:
  


  Don't forget, this is a
Magnum inverter
and Magnum has issues. I have  two customers with
Magnum problems. One
is a washer that will work  perfectly on a cheap
import inverter; the
other has a Vizio TV that  works fine on shore power
and generator.
S...maybe there are pumps  and other items that
are anti-Magnum.







Larry Crutcher



Starlight Solar



(928) 941-1660



Renewable Energy Products, Service and Installation




  







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Re: [RE-wrenches] solid vs stranded AC vs DC

[boB Gudgel]

Wind-sun.com wrote:

See http://en.wikipedia.org/wiki/Eddy_current

The practical effects of running a single wire in 98% of the systems 
that any solar installers will ever see is probably just about zero, 
and it also only applies to AC currents (or rapidly varying DC, which 
is not common). 
Won't make a noticeable difference in the small stuff in this industry 
most all of the time.


Brian Teitelbaum said:

Is that true even for non-ferrous metals, like aluminum, or say, gold?


Yes.  Anything that conducts electricity would be susceptible to eddy 
currents.  (IF it ~did~ create a problem that is)
I don't know why anyone here would normally run just one wire through a 
box or conduit though.


boB




The only time I have ever actually seen this happen was several years 
ago when the leads for a large 30 HP/440AC motor were fed by separate 
wires, each in their own metal conduit (don't ask me why...).


.. 


Northern Arizona Wind & Sun - Electricity From The Sun Since 1979
Solar Discussion Forum: http://www.wind-sun.com/ForumVB/
.. 

- Original Message - From: "Brian Teitelbaum" 


To: "RE-wrenches" 
Sent: Monday, August 03, 2009 1:12 PM
Subject: Re: [RE-wrenches] solid vs stranded AC vs DC



Hey Darryl,

You said - " never allow a single wire to pass through a metal 
surface as this will induce eddy currents and magnetic effects into 
the metal causing voltage drop and heating"


Is that true even for non-ferrous metals, like aluminum, or say, gold?

Brian Teitelbaum
AEE Solar



-Original Message-
From: re-wrenches-boun...@lists.re-wrenches.org 
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of 
Darryl Thayer

Sent: Monday, August 03, 2009 1:01 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] solid vs stranded AC vs DC


I looked in the code book and found stranded wire has about 2% higher 
DC resistance than solid, Chapter 9 table 8, and that for AC 
resistance the same value as DC resistance to within the table 
accuracy Chapter 9 Table 9


This table points out that for AC resistance it is important to know 
the conduit system, as the reactance will have an effect.  With AC it 
is important to never allow a single wire to pass through a metal 
surface as this will induce eddy currents and magnetic effects into 
the metal causing voltage drop and heating.


--- On Fri, 7/31/09, jay peltz  wrote:


From: jay peltz 
Subject: Re: [RE-wrenches] solid vs stranded  AC vs DC
To: "RE-wrenches" 
Date: Friday, July 31, 2009, 10:01 PM
Hi Darryl,

But what are the differences and when do they come into
play?




On Jul 31, 2009, at 7:25 PM, Darryl Thayer wrote:

>
> Well there is very slight differences between AC and
Dc But this
> difference
> is so slight that it has no effect on anything we will
do.
> Darryl
> --- On Fri, 7/31/09, jay peltz 
wrote:
>
>> From: jay peltz 
>> Subject: [RE-wrenches] solid vs stranded  AC
vs DC
>> To: "RE-wrenches" 
>> Date: Friday, July 31, 2009, 7:00 PM
>> HI All,
>>
>> I'm trying to understand this wire issue.
>>
>> Whether or not there is a difference between
stranded or
>> solid wire for DC or AC.
>>
>> Any takers on this one?
>>
>> thanks,
>>
>> jay
>>
>> peltz power
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Re: [RE-wrenches] solid vs stranded AC vs DC

[boB Gudgel]

Matt Tritt wrote:

Darryl,

Say what?! This would seem to indicate that solid core is actually 
better for DC than stranded wire. Can this possibly be true??


Matt



The reason that stranded is higher resistance than solid is that there 
is more "air" in between the strands.  Solid
wire doesn't have that empty space.  It's harder to maneuver though and 
can be harder on breaker studs for the
big stuff.   Stranded doesn't have any (or VERY little) effect on AC 
since the strands are not normally insulated

from each other.

However, multiple strands of insulated magnet wire in transformer 
manufacturing and other things DO have positive effects

and is done all the time to reduce high frequency effects.

boB






Darryl Thayer wrote:

I looked in the code book and found stranded wire has about 2% higher DC 
resistance than solid, Chapter 9 table 8, and that for AC resistance the same 
value as DC resistance to within the table accuracy Chapter 9 Table 9

This table points out that for AC resistance it is important to know the conduit system, as the reactance will have an effect.  With AC it is important to never allow a single wire to pass through a metal surface as this will induce eddy currents and magnetic effects into the metal causing voltage drop and heating.  


--- On Fri, 7/31/09, jay peltz  wrote:

  

From: jay peltz 
Subject: Re: [RE-wrenches] solid vs stranded  AC vs DC
To: "RE-wrenches" 
Date: Friday, July 31, 2009, 10:01 PM
Hi Darryl,

But what are the differences and when do they come into
play?




On Jul 31, 2009, at 7:25 PM, Darryl Thayer wrote:



Well there is very slight differences between AC and
  
Dc But this  


difference
is so slight that it has no effect on anything we will
  

do.


Darryl
--- On Fri, 7/31/09, jay peltz 
  

wrote:


From: jay peltz 
Subject: [RE-wrenches] solid vs stranded  AC


vs DC


To: "RE-wrenches" 
Date: Friday, July 31, 2009, 7:00 PM
HI All,

I'm trying to understand this wire issue.

Whether or not there is a difference between


stranded or


solid wire for DC or AC.

Any takers on this one?

thanks,

jay

peltz power
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Re: [RE-wrenches] utility line voltage issues

[boB Gudgel]

Marv Dargatz wrote:
Check out the following link.  Just ONE example of what the utility 
must deal with.


http://tdworld.com/customer_service/power_new_technology_solves/

I'm not defending the utilities.  They definitely have their faults 
(argh, argh), but they have some severe challenges that we are not 
always sensitive to.


See Ya!

Marv
Enphase Energy
707 763-4784 x7016



In some cases, like for this flicker problem example due to irrigation 
pumps turning on, it sounds like the ieee1547 spec needs
to be able to relax somewhat to give the inverter time to help out the 
brownout condition.


I kind of doubt that the lineman will be fixing the problem withing 2 
seconds, the present disconnect time allowed, let alone,
a small-ish grid tie inverter being able to even drive the local 
transformer and/or neighborhood loads without REALLY turning
off.  I know... The spec is trying to protect everything and everybody 
for every possible situation.


Like Richard Perez once said in a radio interview with Art Bell, "The 
grid needs your help".


boB







William Miller wrote:

William:

It was my understanding that in special circumstances, inverter 
manufacturers are allowed to widen the allowances for specific 
units.  IIRC, a letter from the utility was required.  In some 
inverters, a change of firmware with the more liberal settings does 
the job.  My memory is subject to verification.



William Miller



At 10:06 AM 8/16/2009, you wrote:
I'm beginning to wonder if the allowed voltage range for grid-tie 
inverters (+/-10%) is too
sensitive in some networks and contributes more harm than benefit. 
This is close to home.



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Re: [RE-wrenches] power factor

[boB Gudgel]

Drake Chamberlin wrote:

One question about power factor:

We know it is the ratio of the real power to the apparent power, and 
that most utility meters only register real power (watts).  Reactive 
power doesn't dissipate as heat like power loss through a resistor. 

The question is:  What is the quantitative effect that reactive power 
has on a battery bank that is feeding loads through an inverter?  If 
the power factor is 56% (like a refrigerator that I want to replace) 
does that mean that only 56% of the power being drawn from the 
batteries is being used to power the refrigerator?.  If so, where does 
the rest of the power go? 


If you just take your meter and multiply Volts X Amps, that's VA, or 
apparent power.   If it's all real, then it's like the resistor and gets 
counted by
the utility meter.  Some turns into heat (resistor) and some gets some 
real work done.


The rest, is VA but is Reactive and is  VA Reactive or VARs.

So, the reactive current that comes out of the batteries, into the 
inverter out the AC output, comes BACK into the battery.  (this is for 
an inverter

that has the ripple reflecting back into the battery)

So, your batter kind of discharges and then recharges 120 times per 
second for a 60 Hz system.
So, where does the power go ?   The real power gets used of course and 
most of the rest, the VARs gets put back into
the battery.   HOWEVER, since the transformer and wire and FETs and 
transormer and stuff have resistance, some of those VARS get turned
into heat by that inefficiency, or I-squared-R losses.  That's one 
reason why low power factor isn't so good.


Does that kind of make sense ?

boB



Thanks,

Drake Chamberlin
Athens Electric
OH License 44810
CO License 3773
NABCEP TM  Certified PV Installer
Office - 740-448-7328
Mobile - 740-856-9648



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Re: [RE-wrenches] power factor

[boB Gudgel]

Brian Teitelbaum wrote:

boB,

Not only does that make sense, it's the best explanation of the effect of power 
factor on an off-grid system that I've read.

I would than assume that this means that Drake's refrigerator is actually consuming more 
power from his battery system than is just measured in AC watts at the fridge. Some 
energy is lost as heat in the inverter system while the fridge is running, at least more 
than would be if the fridge had a higher power factor. I would also assume that measuring 
the DC amperage in the battery cables, and subtracting the "normal" inverter 
losses, would give a more accurate reading of the Fridge's true running watts.

There are a number of plug-in products on the market that are supposed to 
improve power factor, apparently through added capacitance. How would they work 
here, or would they?
  

Great question and I'm not sure I have a good answer.

You would have to modify the refrigerator itself to make it have a 
higher power factor, and I would hope that the appliance manufacturer 
has designed it to work as
good as it can.  Are those high efficiency refrigerators power factor 
corrected though, since Europe requires power factor close to 1.0 and 
the good ones

are also used there ?

I've seen many discussions about those power factor correction units for 
home use, and I think the consensus is that they really don't help much, 
if at all

...Mainly because the homeowner only pays for real power.

I think that the higher the inverter efficiency, the better it will work 
with lower PF loads, because it has to keep its AC source impedance low when
powering that refrigerator (or whatever), because it has  to circulate 
and "slosh" around those reactive currents.


Lower resistance  =equals=  higher efficiency,  =equals=  better low 
power factor performance,  is one way to look at that.


Adding extra and opposite reactance  for power factor correction is 
something that utilities do at large reactive consumers such as steel 
mills.  It makes sense for that
type of power usage.   BTW, if the primary power factor is low because 
of big inductive loads, they add capacitors, and if capacitive, they add 
inductors to pull the power
factor  back towards 1.0.  At least that's the "passive" method that I'm 
familiar with for low Displacement Power Factor, (DPF).


But what happens if you have all that passive PF correction in place, 
and all of a sudden the load reduces or goes resistive ? Then you're left
with a nice low power factor load again.  (I think they take that into 
account and make it average out).


Then, there's active, electronic PFC.I probably won't be around to 
see, but I bet that high temperature

superconductors will play a big roll in reducing all losses.

boB


Brian Teitelbaum
AEE Solar



-Original Message-
From: re-wrenches-boun...@lists.re-wrenches.org 
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of boB Gudgel
Sent: Wednesday, August 19, 2009 9:28 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] power factor

Drake Chamberlin wrote:
  

One question about power factor:

We know it is the ratio of the real power to the apparent power, and
that most utility meters only register real power (watts).  Reactive
power doesn't dissipate as heat like power loss through a resistor.

The question is:  What is the quantitative effect that reactive power
has on a battery bank that is feeding loads through an inverter?  If
the power factor is 56% (like a refrigerator that I want to replace)
does that mean that only 56% of the power being drawn from the
batteries is being used to power the refrigerator?.  If so, where does
the rest of the power go?



If you just take your meter and multiply Volts X Amps, that's VA, or
apparent power.   If it's all real, then it's like the resistor and gets
counted by
the utility meter.  Some turns into heat (resistor) and some gets some
real work done.

The rest, is VA but is Reactive and is  VA Reactive or VARs.

So, the reactive current that comes out of the batteries, into the
inverter out the AC output, comes BACK into the battery.  (this is for
an inverter
that has the ripple reflecting back into the battery)

So, your batter kind of discharges and then recharges 120 times per
second for a 60 Hz system.
So, where does the power go ?   The real power gets used of course and
most of the rest, the VARs gets put back into
the battery.   HOWEVER, since the transformer and wire and FETs and
transormer and stuff have resistance, some of those VARS get turned
into heat by that inefficiency, or I-squared-R losses.  That's one
reason why low power factor isn't so good.

Does that kind of make sense ?

boB

  

Thanks,

Drake Chamberlin
Athens Electric
OH License 44810
CO License 3773
NABCEP TM  Certified PV Installer
Office - 740-448-7328
Mobile - 740-856-9648

--

Re: [RE-wrenches] Helix Wind

[boB Gudgel]

Keith Cronin wrote:

http://www.helixwind.com/en/index.php

Anyone have any feedback on these?

Thanks
  


You might as Mick Sagrillo.  He's evidently doing some consulting for them.

http://www.helixwind.com/en/newsDetail.php?nid=62


Although, I bet that Helix Wind will have anybody working for them signing
some kind of NDA and not be able to tell you much.  Just a guess from what
I've seen with other VAWT manufacturers.   It's all hush-hush bleeding edge
stuff you know !

boB










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Re: [RE-wrenches] raintite box mounting angle

[boB Gudgel]

Conrad Geyser wrote:


We always fill any conduit at the point of building penetrations for 
air sealing. Otherwise in winter, not only will the conduit get house 
moisture condensing inside of it, but it will act a a nice thermo 
siphon for pulling warm air out of the house…..




Just a note here...

All six of the MidNite PV combiner boxes are rain "proof", but allow moisture 
to escape.

boB











*From:* re-wrenches-boun...@lists.re-wrenches.org 
[mailto:re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of 
*Wind-sun.com

*Sent:* Tuesday, August 25, 2009 11:49 AM
*To:* jry...@netscape.com; RE-wrenches
*Subject:* Re: [RE-wrenches] raintite box mounting angle

It is almost impossible in a normal installation to get a totally 
waterproof enclosure.


What you describe with the flooded box is more common than people 
might think.


What causes most of that is condensation. Humid air gets sucked into 
the enclosure at night or whenever else it cools off. The water then 
condenses inside. Next day, the box heats up again and the air expands 
a bit again, but the water has already condensed and cannot get out.


That is why the weep hole as you noted is mandatory, especially in 
areas with high humidity. But we have seen this even in the desert 
regions of Arizona and CA, so it can happen anyplace over long periods 
of time.


..
Northern Arizona Wind & Sun - Electricity >From The Sun Since 1979
Solar Discussion Forum: http://www.wind-sun.com/ForumVB/
..

- Original Message -

*From:* Jeff Yago 

*To:* k...@vtsolar.com  ; RE-wrenches


*Sent:* Tuesday, August 25, 2009 8:40 AM

*Subject:* Re: [RE-wrenches] raintite box mounting angle


I am getting more convinced that there is no such thing as a
water-tight electrical enclosure, regardless of gasket covers and
sealed openings. We always drill a very small "weep-hole" in the
bottom of an enclosure. We have found this is too small to allow
insects to enter, but will drain any leaks or moisture that gets
condensed into a liquid. I was recently called by the owner of a
large pole mounted array (that was installed by another firm )
when the system stopped working and the originally installer was
long gone. I absolutely swear to you that when I pulled the covers
off several electrical junctions boxes, water POURED out of the
enclosures! I am not talking about wet, I am saying about a quart
of water was being held inside each enclosure by their water-proof
gasketed covers. Needless to say, all of the electrical terminals
and wire connectors inside these junction boxes were badly corroded.

I know they make totally water-proof electrical equipment for
under-water applications, but have found most outdoor rated
electical enclosures will get some water inside and that includes
under-ground conduit. Take some advice and regardless of mounting
orientation, drill a small weep-hole in the bottom if there is not
one provided by the manufacturer.

Jeff Yago

DTI Solar



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Re: [RE-wrenches] Magnum Battery Charger Question

[boB Gudgel]

Jason Lerner wrote:

Hi Bob,

I put on an old Todd charger with Voltage regulation,  but not absorb 
and float.  I can change the voltage up or down as needed.  Changing 
out the remote is a good idea.  I do have another Magnum inverter at 
another location,  but was trying to avoid another couple trips


Thanks,

Jason
On Sep 27, 2009, at 9:57 AM, robert ellison wrote:

The custom battery voltage setting mode were not always available in the 
inverters, so it could be, I suppose, the rev of that
unit is not new enough.  I have heard of an instance this was a problem 
with a system.   It doesn't warn you that this feature

is not available of course, just because the remote has it built in.

OR, maybe the unit is just defective?  Hard to see why it would do this, 
but maybe...


Also, it may not be widely known that when  AC is first applied to the 
Magnum inverter for charging, if the battery  is
already above a certain voltage, (float ?), it will not enter the 
Bulk/Absorb cycle.  The battery voltage must be below a certain voltage
while plugging it into the AC before it will Bulk/Absorb.  I don't think 
this is your particular problem though, as we've

already discussed that possibility off line.

boB





I have had real bad luck with Interstate Batteries. That aside here 
are some further ideas.
What type of an external charger are you using? if it is a shop type 
charger, they don't behave the same as the 3 stage charger in a good 
inverter and you can't compare them directly.
 
The best test would be to put another inverter charger on it to see 
how it behaves. Another Magnum would be ideal. Do you have another 
available?
Try a different remote also, just in case there is a problem there. 
That would allow you to mix and mattch the invertes and remotes to 
sort things out.
 
Bob


On Sun, Sep 27, 2009 at 11:44 AM, Jason Lerner 
mailto:wapa...@rockisland.com>> wrote:


Hello Bob,
Yes I have deep cycled the batteries.  I only mentioned the 12.7
because above that voltage it will skip the absorb charge.
 Interstate batteries,  and all the connections are good and
tight,  specific gravity all good as well.

I was thinking maybe it is an intermittent internal connection,
 but I put an external charger on the same battery bank and it
charges just like it should

Thanks for the hints,

Jason

On Sep 26, 2009, at 8:11 PM, robert ellison wrote:


Have you deep cycled the batteries? Normally you would be way
below 12.7 when you had to use a generator to charge,12.7 is
fully charged for a 12 volt pack.
.
Cycle them down to 10.5 to 11 volts or so a few times and charge
them back up.
See if it charges better when cycled.
What brand of batteries are these?
 
The magnum chargers are great, and if shorted it goes to 14.4

volts the charger is fine.
 
Any chance you have bad connection somewhere? If you have one

try using a infared pyrometer to look for a warm connection
somewhere. But it has to be after you charge for a while, give
it time to heat up.
 
Bob


 
On Sat, Sep 26, 2009 at 12:04 PM, Jason Lerner

mailto:wapa...@rockisland.com>> wrote:

Hello All,

Have a question on a Magnum 1212MM-AE.  The battery charger
will not get above 13.8 Volts.  The system worked fine for
the first three weeks with Voltage rising to 14.4 volts for
the absorb cycle,  but now it will not.  The battery size
and type setting are correct,  and using the "custom"
charging profile set to 15 Volts does not work.

We have tried unplugging the BTS,  while also making sure
the battery Voltage is below 12.7 when starting the
generator.  The remote control is attached and there is 35
amps going into the battery with a 2KW honda.  It will sit
at 13.8 Volts and do an absorb cycle for 2 hours and then go
into float.  There are 4 golf cart batteries in the system
and all cells check out good, no dead cells,  and connection
are all bright and tight. Turning the main DC disconnect off
while the gen is running shows 14.8 Volts at the battery
terminals of the inverter,  but the batteries will not rise
above 13.8.  Magnum says the battery charger is fine since
it goes up to 14.8 when the batteries are disconnected, but
that doesn't make for a very efficient charger if it is not
connected to the batteries..

I am not familiar with these chargers,  did I miss
something,  any ideas?
Thanks,

Jason Lerner
Waldron Power and Light Co.
(888) 927-2526


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Re: [RE-wrenches] Magnum Battery Charger Question

[boB Gudgel]

boB Gudgel wrote:

Jason Lerner wrote:

Hi Bob,

I put on an old Todd charger with Voltage regulation,  but not absorb 
and float.  I can change the voltage up or down as needed.  Changing 
out the remote is a good idea.  I do have another Magnum inverter at 
another location,  but was trying to avoid another couple trips


Thanks,

Jason
On Sep 27, 2009, at 9:57 AM, robert ellison wrote:

The custom battery voltage setting mode were not always available in 
the inverters, so it could be, I suppose, the rev of that
unit is not new enough.  I have heard of an instance this was a 
problem with a system.   It doesn't warn you that this feature

is not available of course, just because the remote has it built in.


Forgot to mention that it should give you the inverter software 
revision, which will be helpful in determining if
the unit has that feature or not.  The factory would have to verify that 
though.


boB





OR, maybe the unit is just defective?  Hard to see why it would do 
this, but maybe...


Also, it may not be widely known that when  AC is first applied to the 
Magnum inverter for charging, if the battery  is
already above a certain voltage, (float ?), it will not enter the 
Bulk/Absorb cycle.  The battery voltage must be below a certain voltage
while plugging it into the AC before it will Bulk/Absorb.  I don't 
think this is your particular problem though, as we've

already discussed that possibility off line.

boB



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Re: [RE-wrenches] AC Coupled Re-visited

[boB Gudgel]

Jeff Yago wrote:

There have been some good advice related to battery bank sizing and a better 
description of how Sunny Islands work with SunnyBoys, but I am afraid we are 
getting away from my original post that started this and that was:

Since a battery based inverter has a battery charging section and all kinds of software 
control over the charging process when connected to the grid, why does the battery 
charging process "go wild" when the grid is down and the AC power is being 
backfed from a separate AC coupled inverter.  Also, why do we keep having to field wire 
and program an added power relay or a separate diversion load relay to prevent 
over-charging and destroying an AGM battery bank because the battery charging process 
suddenly has no clue how to charge the battery bank.
  


Because, people are using these inverters in ways they were not really 
meant to be used.   It can be made to work, but the inverter is not 
"aware" of the battery voltage in this mode

of operation

Actually, another way to look at this is to put the onus on the grid tie 
inverter rather than the battery based inverter, providing the reference 
grid, to
be able to easily turn its power level down.   SMA just happens to have 
a way to do this in a pretty slick way.


 The regular battery based inverter, like the FX or Magnum, etc,  is 
"bidirectional".  When the grid-tie inverters voltage gets pushed up
because the battery based inverter has nowhere to put that energy, the 
AC voltage rises and so the DC battery voltage side must rise

as well.

That is, unless some inverter like the SI tells the grid tie inverter to 
lower its output power, the grid tie inverters' voltage will try to rise to
try and sell more power to the "grid".But there is no "grid" when 
the batteries are full, so the grid tie inverters' AC voltage goes out

of UL range, and goes off line.

Yes, the Sunny Island varies frequency which will cause an AC coupled SunnyBoy to be faked out and drop off line to avoid overcharging the battery bank, but it seems to me this is all just software programming, so why can't any inverter manufacturer simply control battery charging no matter where the AC power is coming from? 
Other's could do this too, if they know what Grid-tie inverter is that 
they are tied to and how to control it (like varying frequency).   
SMOP Simple Matter
Of Programming as they say.   That is, ~IF~ the grid-tie inverter can be 
turned down.  This is the best way.   The battery based inverter can not 
use the energy.
It can't just keep the AC voltage at 120V and the battery voltage down 
if the grid tie inverter is trying to raise that AC voltage by trying to 
sell to it.


Otherwise, all the battery based inverter can do is to turn off.  Then, 
of course, the reference for the grid tie inverter goes off, and it must 
wait another

5 minutes after the battery based inverter starts inverting again.

 Why can't grid tie inverters used in an AC coupled application have the software to recognize a full battery condition and stop charging without having to drop off line on an out of limit grid condition and then cycle through the 5 minute wait? 
  


It's because it's not a charger at this point... It's a bi-directional 
"inverter".



I am not an electronics engineer, but I don't see where any hardware changes are 
required, just some added software to select during initial setup.  Many of you may not 
deal with battery based systems, but half of our systems are and AC coupled is a great 
way to avoid long low voltage DC wire run losses.   We select generator type from a setup 
menu, how about "Press 1 for standard inverter setup, press 2 for AC coupling".
  


It's kind of like when your stomach is full, you have to stop being fed, 
otherwise you get real sick.  (sort of)


boB






Jeff Yago

_
Netscape.  Just the Net You Need.
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Re: [RE-wrenches] SW Parallel stacking cable

[boB Gudgel]

Brian Teitelbaum wrote:


William,

 

The SW Parallel Stacking Interface (SWI/PAR) was much more than just a 
cable (like the Series Stacking Cable -SWI). it was a separate box, 
like the Grid Tie Interface (GTI) unit was. It retailed for about $345.00


 


Good luck finding one.

 


Brian Teitelbaum

AEE Solar




For parallel, I believe a current balancing transformer was involved 
besides the synchronization cable.
That's why it was more involved than just a cable.  Since there can be a 
few volts difference between

the 2 stacked SWs.

boB





 

 

 

*From:* re-wrenches-boun...@lists.re-wrenches.org 
[mailto:re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of 
*William Miller

*Sent:* Wednesday, November 04, 2009 9:59 AM
*To:* RE-wrenches
*Subject:* [RE-wrenches] SW Parallel stacking cable

 


Friends:

I received an inquiry from a solar contractor looking for a PARALLEL 
stacking cable for SW inverters.  I have never laid eyes on such a 
cable.  Did they exist?  Does anyone have one or a diagram?


Many thanks,

William Miller


_Please note new e-mail address and domain:

_William Miller
Miller Solar
Voice :805-438-5600 Fax: 805-438-4607   
email: will...@millersolar.com

http://millersolar.com
License No. C-10-773985



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Re: [RE-wrenches] Strings and series of batteries with reverse return linkup

[boB Gudgel]

Antony Tersol wrote:
Assume 3 parallel battery stings, with identical batteries of internal 
resistance r.


Assume identical wire leads of resistance R.

Then when the batteries have the same state of charge and their 
internal resistances are equal, one can solve for the current in each 
string.


I1 = I3
I2 = I1 r / (r+R)

where I2 is charging current thru the middle string.

The amount that the middle current is reduced is a function of the 
relative sizes of the wire and battery resistances.


For R << r, I2 --> I1.
For r << R, I2 --> 0.

With a buss bar arrangement, I1 = I2 = I3 = V/(2R + r)


One thing this does not take into account though, is the inductance of 
all the wires brought
on by the wire lengths and their loop area, which in a usual inverter 
with ripple current, will also limit the current
through the system...   That will also have some undesired consequences 
with the voltages

seen at the inverter terminals due to resonances, etc.

In ~can~ be significant.

boB


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Re: [RE-wrenches] Power Factor and Grid Tied PV

[boB Gudgel]

swingjun...@gmail.com wrote:

Thanks to all who responded,

The article Marco references, is the one referenced in the tinyurl in 
my original post. I did not find anything of significance in the 
previous Solar Pro issues. Based on the responses it seems there is no 
good data out there to answer the question posted. This may be due to


1) the fact that PV systems are not being installed in commercial 
facilities with large reactive loads
2) those facilities are not penalized for PF therefor the question is 
irrelevant to those system owners
3) the PV systems installed in such facilities are small with respect 
to the overall facilities load and any negative impact on PF is 
insignificant


Cheers
Carl
  


I don't think there is anything to be concerned about if the PF goes 
down because a grid tie inverter is helping
to support the real power loads.  The I-squared-R losses won't get any 
larger for the utility.  I think it's just
because the Numerator of   Watts / VAR goes down, and the denominator 
staying the same that is

making the measure Power Factor measurement go down.

Also, I believe that this is only for "current source" inverters, which 
accounts for most GT inverters today...
An older SW inverter,  say, (voltage source) would actually supply VARs 
to the system and probably

wouldn't change the measured PF to the utility very much, if at all.

My 2 cents for today.
boB











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Re: [RE-wrenches] kW/MW v. kWh/MWh

[boB Gudgel]

Ian Woofenden wrote:


This is one of my pet peeves too...

A few snippets and observations from my frequently given electrical 
terms presentation:


If I asked you "How far is it to Vancouver?" and you answered "45 
miles per hour," everyone listening would know that someone was 
confused. But we tolerate and even perpetuate this kind of confusion 
daily with the terms "watt" and "watt-hour", which are directly 
comparable to miles per hour and miles (NOT the reverse). The terms 
themselves are very confusing, since a watt (which might sound like a 
quantity/unit) is shorthand for "joule per second," the rate of energy 
generation, transfer, or use, while a watt-hour is a unit of energy 
(even though it might remind some people of "miles per hour", with 
"hour" in it).


I'm amazed when some long-time RE folks say things like, "Oh, it 
doesn't matter..." when they say "kilowatt" when they mean 
"kilowatt-hour". This sort of ignorance and brush-off just makes our 
job of energy education harder.


I've begun to teach watts and watt-hours FIRST in my presentations, 
instead of the more common order of volts, amps, amp-hours, watts, and 
watt-hours. Watts and watt-hours are the most important measures and 
the most important distinction, and if I lose students after that, 
it's better than losing them before understanding these crucial terms.


For the general public, I completely downplay amps and amp-hours, 
which are really an internal measurement perhaps analogous to 
something like cylinder displacement in an engine, in a world where 
people want to know fuel economy and speed. If I ran the circus, we'd 
rate batteries in watt-hours, have watts and watt-hours on every 
consumer RE system gauge, and leave amps and amp-hours to the geeks 
who need them (for wire sizing, for example).


And going down that road a bit, one of the most helpful moments of 
understanding for me was when years ago my guru Bill Beaty said that 
"two things flow in electrical circuits -- charges and energy". Amps 
and amp-hours describe charge flow and quantity, while watts and 
watt-hours describe energy flow and quantity.


I agree with all of what you say, when it comes to Watts and Watt-Hours, 
Ian, except for your (and Bill's) insistence on not using the words 
"Current Flow" to describe
the direction of current.   I know we've gone over this many times 
before, and I know what you mean, but you and Bill Beaty will (almost) 
single handedly have to convince the
rest of the world, scientists and engineers, including one of Bill 
Beaty's gurus, Richard Feynman, from NOT using the terms "current flow", 
and even sometimes "Power flow",
which the power industry and engineers constantly use when referring to 
the "direction" of power.  Good luck on that.


If you are going to try and change those particular usages, try to come 
up with an easy way of saying it though.  Some kind of wording that 
"flows"  {:-)




Of course, as others have noted, we can talk about generating or 
storage sources in terms of their power (kW) or energy (kWh) capacity, 
but there is such confusion about the terms, it's better to be 
redundantly clear about what we mean, and make sure we're accurate.


Being redundantly clear is the reason (I think) that those two words  
"Current Flow" and "Power Flow" are used.  I don't have a problem with 
it.  I also don't have any problem with
you making people at least "aware" of what it really means.  But you 
can't stop the world from turning.


My two Watts worth. (or is that Watt-Hours?)...  AND, don't forget to 
capitalize the word Watts which is the name of a famous dead scientist.


boB





Encouraging electrical terminology literacy, one wrench and newbie at 
a time, ;-)


Ian

At 9:42 AM -0800 1/18/10, Peter Parrish wrote:
Just a pedagogical note. Since I have been teaching PV Installation 
now fairly continuously since July of this year. The kW/kWh problem 
is pretty pervasive: I even slip once and a while. Here is the 
problem as I see it.
 
Most basic units like mass, distance, energy are simply defined: 
kilogram, meter and joule. The rates of change are derived: 
kilometers per hour, meter per second, joule per second (watt).
 
The basic units related to energy (at least within the electrical 
utility and related fields) are defined first with the rate of 
change: watts (or joule per second). Then the other quantities are 
derived from the watt: watt-hour (energy), watts/meter-squared 
(insolation) and the like.
 
Well that's just a fact, and in my classes I drive that point home 
early and often - so as to minimize confusion down the road. To 
enliven things a bit, I also add a little history.
 
In the 18th and 19th centuries, there was a lot of work done trying 
to understand the nature of and interrelationship between mechanical 
work, heat and then later electricity. The early work focused on the 
rate at which work could be done, and concepts like horsepower and 
later watts were used and co

Re: [RE-wrenches] Inverter causing migraine?

[boB Gudgel]

Dan Fink said:

"That's a tricky situation. There are only two possibilities for what's 
causing the problem; sound or electromagnetic radiation"


I'm betting that it's sound.  Remember how you could hear televisions 
singing

away at 15 kHz ??  That still gives some people headaches.

How old is this customer ??   I'm guessing he's young because it's most 
likely because he
can hear the inverter switching.We just can't normally hear 
them  The FX/VFX
inverters switch at around 20 kHz which some people can still hear.  
Especially younger ones

with better hearing.

It's probably the transformer windings and iron acting as a 
speaker/transducer.


High frequencies are very directional so will usually respond well to a 
thin wall  of

padding between inverter and the rest of the inside of the house or cabin.
That should help reduce the acoustical output.

boB






Dan Fink wrote:

Joel --
Good points. In a recent newspaper article in Boulder, CO about a 
really bad PV install, the direct grid tie inverter was mounted right 
on the outside of the wall from the homeowner's bed. They finally had 
to have it moved--mostly because of buzzing, but EMF was a concern 
too. It was basically less than a foot from the guy's pillow.


Also, I forgot to mention that there are fairly inexpensive EMF meters 
available from the same places that sell DIY shielding materials.


The biggest source of EMF at *my* house is actually the E-Meter 
measuring amp-hours. It even interferes with my handheld ham and fire 
department radio FM communications on 2 meter.


DAN FINK
Renewable Energy Consultant




Joel Davidson wrote:

Ron,

Electromagnetic fields are produced any time you have current flowing 
through wire. They are low frequency waves that drop off rapidly 
proportional to the distance from the source. Inverters, 
transformers, fluorescent light ballasts, motors, clock radios, power 
blocks, microwave ovens, kilowatt hour meters, service panels all 
emit EMF. There is no
practical way to block EMF.  It passes through almost everything 
including walls and even lead. There is no U.S. safety standard for 
EMF. Some say 8 milligauss or more is dangerous and 2.5 milligauss or 
less is safe.


I went through our home about 10 years ago using a borrowed 
milligauss meter (thanks David Katz). Our utility meter service had 
significant EMF, but that was not a problem since it is mounted on an 
outside wall and there is a closet between the living space and the 
meter. The EMF had fallen to below 2 milligauss between the wall and 
the closet door. The bedroom clock radio was the second largest EMF 
source in our home. Moving the clock 1 foot away from the bed to the 
other side of the night stand brought the EMF levels under 2 
milligauss. Our SW4048 inverter emitted a field that fell to a safe 
level 2 feet from the inverter.


I tell people not to put their bed against the wall where their 
utility service panel or inverter is mounted. I also tell them that 
the Japanese did a 2 year study of school children riding the Tokyo 
subway (big EMF emitter) and found that there was no danger.


Some sounds that most of us take for granted can cause physical 
discomfort and even pain. SW4048 and other transformer and electrical 
and electronic buzzing can be annoying. Also certain wavelengths and 
intensities of light can cause pain and injury.


Joel Davidson

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Re: [RE-wrenches] Inverter causing migraine?

[boB Gudgel]

Ron Young wrote:

Mike,

Some interesting points, thank you. I would have attributed the 
problem to several of the mentioned issues, medications (HRT), 
clenching, tension... But what happened a couple of days ago makes me 
wonder. I turned on the inverter without her knowledge and within two 
minutes she was complaining and asked me if it was on. It was right at 
quitting time and she was out of the environment within 7-8 minutes 
but the next day she complained that she had a "migraine" that night.


Ron


Yep, it's gotta be the sound.  I'm 95+% sure...

  If you want to try to tweak things, a decent microphone running into 
a higher sample
rate A/D on a laptop with  (96 kHz or 192 kHz) and a program with 
spectrum analyzer can help
to adjust things to possibly quiet it down some.  Maybe if you know 
someone into audio you could
have them come over and bring their goodies to help you sorta "see" the 
sound in the room.


Then, you could try tweaking things lik, tightening screws and putting 
in a baffle or
something until that 20 kHz frequency spike comes down, say, 10 or 20+ 
dB or so.


Might just work.  But, then again.
boB





On 4-Feb-10, at 6:41 PM, Ron Young wrote:


forwarded from earth2


Begin forwarded message:

*From: *"Michael Gullo" <mailto:mgul...@comcast.net>>

*Date: *February 4, 2010 5:47:56 PM PST (CA)
*To: *"RE-wrenches" <mailto:re-wrenches@lists.re-wrenches.org>>

*Subject: **Re: [RE-wrenches] Inverter causing migraine?
**Reply-To: *RE-wrenches <mailto:re-wrenches@lists.re-wrenches.org>>


Hi Ron and the group,

The attribution of negative health effects to exposure to 
electromagnetic fields or activated electric equipment has not been 
confirmed in random double-blind provocation studies involving 
persons reporting hypersensitivity to electricity. Before we accuse 
are hard-working inverters, let's look at some facts. There are 13 
different categories of headaches which are divided into over 129 
sub-types. Many people call every headache they experience as 
migraine when in fact there are specific inclusion criteria to make 
diagnosis of migraine. The "rubber band tightening around my head" 
is a classic symptom of tension-type headache. Given a mid 50's 
female, there are more likely one or more provoking factors: 
medications, sleep pattern, hormonal replacement therapy, stress 
(clenching, TMJ), smoker, foods (aged cheese, alcohol, caffeine, 
chocolate, dairy products, MSGs, etc). Does she work at a computer 
using a chair with no arms and no lower back support with a monitor 
slightly higher than eye level? This is an extremely common scenario 
in which the employee comes to work symptom-free and by 12 or 1:00 
develops a headache or neck ache. If she really wants some answers, 
she will need to keep a headache diary for several weeks and seek 
professional help. You could cycle the inverter on/off to see if 
there is a direct correlation between the incidence of the headaches 
and runtime of the inverter. BTW, the placebo effect, as mentioned 
in other emails, is between 40-60% effective at resolving symptoms. 
Hope this helps a bit.


Mike
Michael Gullo
Solar Solutions LLC
Marlton, NJ

NABCEP Certified PV Installer T
Diplomate American Board of Orofacial Pain

- Original Message - From: "Ron Young" 
mailto:solarea...@solareagle.com>>
To: "RE-wrenches" <mailto:re-wrenches@lists.re-wrenches.org>>

Sent: Thursday, February 04, 2010 1:19 PM
Subject: Re: [RE-wrenches] Inverter causing migraine?



Bob,
Not a customer, an employee who works for me. She is mid 50's and 
has very good hearing. You may be right about sound. I also think 
there's  a significant portion of psychosomatic in the mix but I 
wanted to find  out if there were other instances of people 
experiencing distress from inverter operation just to rule out the 
possibility -or take it into account.


I know that some people are becoming more sensitive to 
environmental influences but this inverter is quiet, just the usual 
fan sound occasionally. I used to be able to hear the sound of an 
ultrasonic  alarm system back when I was in my 20's & 30's - now I 
just hear  ringing in my ears.


Ron


On 4-Feb-10, at 1:30 AM, boB Gudgel wrote:



Dan Fink said:

"That's a tricky situation. There are only two possibilities 
for  what's causing the problem; sound or electromagnetic radiation"


I'm betting that it's sound.  Remember how you could 
hear  televisions singing

away at 15 kHz ??  That still gives some people headaches.

How old is this customer ??   I'm guessing he's young because 
it's  most likely because he
can hear the inverter switching.We just can't normally 
hear  them The FX/VFX
inverters switch at around 20 kHz which some people can still 
hear. Especially younger ones

wit

Re: [RE-wrenches] Inverter causing migraine?

[boB Gudgel]

2 or 1:00
develops a headache or neck ache. If she really wants some answers,
she will need to keep a headache diary for several weeks and seek
professional help. You could cycle the inverter on/off to see if
there is a direct correlation between the incidence of the headaches
and runtime of the inverter. BTW, the placebo effect, as mentioned
in other emails, is between 40-60% effective at resolving symptoms.
Hope this helps a bit.

Mike
Michael Gullo
Solar Solutions LLC
Marlton, NJ

NABCEP Certified PV Installer T
Diplomate American Board of Orofacial Pain

- Original Message - From: "Ron Young"
mailto:solarea...@solareagle.com>>
To: "RE-wrenches" mailto:re-wrenches@lists.re-wrenches.org>>
Sent: Thursday, February 04, 2010 1:19 PM
Subject: Re: [RE-wrenches] Inverter causing migraine?


  

Bob,
Not a customer, an employee who works for me. She is mid 50's and
has very good hearing. You may be right about sound. I also think
there's  a significant portion of psychosomatic in the mix but I
wanted to find  out if there were other instances of people
experiencing distress from inverter operation just to rule out the
possibility -or take it into account.

I know that some people are becoming more sensitive to
environmental influences but this inverter is quiet, just the usual
fan sound occasionally. I used to be able to hear the sound of an
ultrasonic  alarm system back when I was in my 20's & 30's - now I
just hear  ringing in my ears.

Ron


On 4-Feb-10, at 1:30 AM, boB Gudgel wrote:



Dan Fink said:

"That's a tricky situation. There are only two possibilities
for  what's causing the problem; sound or electromagnetic radiation"

I'm betting that it's sound.  Remember how you could
hear  televisions singing
away at 15 kHz ??  That still gives some people headaches.

How old is this customer ??   I'm guessing he's young because
it's  most likely because he
can hear the inverter switching.We just can't normally
hear  them The FX/VFX
inverters switch at around 20 kHz which some people can still
hear. Especially younger ones
with better hearing.

It's probably the transformer windings and iron acting as a
speaker/ transducer.

High frequencies are very directional so will usually respond
well  to a thin wall  of
padding between inverter and the rest of the inside of the house
or cabin.
That should help reduce the acoustical output.

boB






Dan Fink wrote:
  

Joel --
Good points. In a recent newspaper article in Boulder, CO about a
really bad PV install, the direct grid tie inverter was
mounted  right on the outside of the wall from the homeowner's
bed. They  finally had to have it moved--mostly because of
buzzing, but EMF  was a concern too. It was basically less than a
foot from the guy's  pillow.

Also, I forgot to mention that there are fairly inexpensive
EMF  meters available from the same places that sell DIY
shielding  materials.

The biggest source of EMF at *my* house is actually the E-Meter
measuring amp-hours. It even interferes with my handheld ham
and  fire department radio FM communications on 2 meter.

DAN FINK
Renewable Energy Consultant




Joel Davidson wrote:


Ron,

Electromagnetic fields are produced any time you have
current  flowing through wire. They are low frequency waves that
drop off  rapidly proportional to the distance from the source.
Inverters,  transformers, fluorescent light ballasts, motors,
clock radios,  power blocks, microwave ovens, kilowatt hour
meters, service  panels all emit EMF. There is no
practical way to block EMF.  It passes through almost everything
including walls and even lead. There is no U.S. safety
standard  for EMF. Some say 8 milligauss or more is dangerous
and 2.5  milligauss or less is safe.

I went through our home about 10 years ago using a
borrowed  milligauss meter (thanks David Katz). Our utility
meter service  had significant EMF, but that was not a problem
since it is  mounted on an outside wall and there is a closet
between the  living space and the meter. The EMF had fallen to
below 2  milligauss between the wall and the closet door. The
bedroom clock  radio was the second largest EMF source in our
home. Moving the  clock 1 foot away from the bed to the other
side of the night  stand brought the EMF levels under 2
milligauss. Our SW4048 inverter emitted a field that fell to a
safe level 2 feet from the inverter.

I tell people not to put their bed against the wall where their
utility service panel or inverter is mounted. I also tell
them  that the Japanese did a 2 year study of school children
riding the  Tokyo subway (big EMF emitter) and found that there
was no danger.

Some sounds that most of us take for granted can cause physical
discomfort and even pain. SW4048 and other transformer and
electrical and electronic buzzing can be annoying. Also certain
wave

Re: [RE-wrenches] Inverter causing migraine?

[boB Gudgel]

gt;>
*Date: *February 4, 2010 5:47:56 PM PST (CA)
*To: *"RE-wrenches" mailto:re-wrenches@lists.re-wrenches.org>>
*Subject: **Re: [RE-wrenches] Inverter causing migraine?
**Reply-To: *RE-wrenches mailto:re-wrenches@lists.re-wrenches.org>>

Hi Ron and the group,

The attribution of negative health effects to exposure to
electromagnetic fields or activated electric equipment has not been
confirmed in random double-blind provocation studies involving
persons reporting hypersensitivity to electricity. Before we accuse
are hard-working inverters, let's look at some facts. There are 13
different categories of headaches which are divided into over 129
sub-types. Many people call every headache they experience as
migraine when in fact there are specific inclusion criteria to make
diagnosis of migraine. The "rubber band tightening around my head"
is a classic symptom of tension-type headache. Given a mid 50's
female, there are more likely one or more provoking factors:
medications, sleep pattern, hormonal replacement therapy, stress
(clenching, TMJ), smoker, foods (aged cheese, alcohol, caffeine,
chocolate, dairy products, MSGs, etc). Does she work at a computer
using a chair with no arms and no lower back support with a monitor
slightly higher than eye level? This is an extremely common scenario
in which the employee comes to work symptom-free and by 12 or 1:00
develops a headache or neck ache. If she really wants some answers,
she will need to keep a headache diary for several weeks and seek
professional help. You could cycle the inverter on/off to see if
there is a direct correlation between the incidence of the headaches
and runtime of the inverter. BTW, the placebo effect, as mentioned
in other emails, is between 40-60% effective at resolving symptoms.
Hope this helps a bit.

Mike
Michael Gullo
Solar Solutions LLC
Marlton, NJ

NABCEP Certified PV Installer T
Diplomate American Board of Orofacial Pain

- Original Message - From: "Ron Young"
mailto:solarea...@solareagle.com>>
To: "RE-wrenches" mailto:re-wrenches@lists.re-wrenches.org>>
Sent: Thursday, February 04, 2010 1:19 PM
Subject: Re: [RE-wrenches] Inverter causing migraine?



Bob,
Not a customer, an employee who works for me. She is mid 50's and
has very good hearing. You may be right about sound. I also think
there's  a significant portion of psychosomatic in the mix but I
wanted to find  out if there were other instances of people
experiencing distress from inverter operation just to rule out the
possibility -or take it into account.

I know that some people are becoming more sensitive to
environmental influences but this inverter is quiet, just the usual
fan sound occasionally. I used to be able to hear the sound of an
ultrasonic  alarm system back when I was in my 20's & 30's - now I
just hear  ringing in my ears.

Ron


On 4-Feb-10, at 1:30 AM, boB Gudgel wrote:



Dan Fink said:

"That's a tricky situation. There are only two possibilities
for  what's causing the problem; sound or electromagnetic 
radiation"


I'm betting that it's sound.  Remember how you could
hear  televisions singing
away at 15 kHz ??  That still gives some people headaches.

How old is this customer ??   I'm guessing he's young because
it's  most likely because he
can hear the inverter switching.We just can't normally
hear  them The FX/VFX
inverters switch at around 20 kHz which some people can still
hear. Especially younger ones
with better hearing.

It's probably the transformer windings and iron acting as a
speaker/ transducer.

High frequencies are very directional so will usually respond
well  to a thin wall  of
padding between inverter and the rest of the inside of the house
or cabin.
That should help reduce the acoustical output.

boB






Dan Fink wrote:

Joel --
Good points. In a recent newspaper article in Boulder, CO about a
really bad PV install, the direct grid tie inverter was
mounted  right on the outside of the wall from the homeowner's
bed. They  finally had to have it moved--mostly because of
buzzing, but EMF  was a concern too. It was basically less than a
foot from the guy's  pillow.

Also, I forgot to mention that there are fairly inexpensive
EMF  meters available from the same places that sell DIY
shielding  materials.

The biggest source of EMF at *my* house is actually the E-Meter
measuring amp-hours. It even interferes with my handheld ham
and  fire department radio FM communications on 2 meter.

DAN FINK
Renewable Energy Consultant




Joel Davidson wrote:

Ron,

Electromagnetic fields are produced any time you have
current  flowing through wire. They are low frequency waves that
drop off  rapidly proportional to the distance from the source.
Inverters,  transformers, fluorescent light ballasts, motors,
clock radios,  power blocks, microwave ovens, kilowatt hour
meters, servi

Re: [RE-wrenches] anti islanding?

[boB Gudgel]

--- On Sat, 2/13/10, August Goers  wrote:

  

From: August Goers 
Subject: [RE-wrenches]  anti islanding?
To: "RE-wrenches" 
Date: Saturday, February 13, 2010, 10:29 AM
Hi Wrenches,

Does anyone know where I can go to read about general
information on how grid tied inver anti islanding works? I'd
like to be able to describe this in better detail to our
tech-savvy clients. 


Thanks,

August






Without having to obtain the UL or IEEE1547 specs, there is some real 
techy information online at Sandia and NREL...  For instance,



http://www.nrel.gov/docs/fy04osti/36243.pdf

http://prod.sandia.gov/techlib/access-control.cgi/2002/021320.pdf


This link includes some Trace SW5548 tests...
http://photovoltaics.sandia.gov/docs/PDF/IEEE%20Jerry%202.pdf

There is lots more if you  Google for it.   I find it interesting, but 
would put most

people to sleep.  Good thing they're looking for techy info.


boB



August Goers

Luminalt Energy Corporation
O: 415.564.7652
M: 415.559.1525
F: 650.244.9167
www.luminalt.com
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Darryl Thayer wrote:
  
Hi 
I hope you get an expert, but here is what I understand.  Of course if the grid goes to zero it is easy to break under voltage.  But if the grid has a motor particularly a synchronous motor, it can generate a sine wave, so the inverter always trys to increase the speed or frequency of the sine wave if it can, or speed up the motor it drives out of the frequency range and shuts down.  also the inverter tries to raise the voltage if it can it shuts down. So the inverter is always trying to raise voltage or increase frequency, if it can it shuts down.   Also in the motor case if the inverter cannot supply enougn power the motor will slow down and the inverter quits suts down.  
Darryl  



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Re: [RE-wrenches] Kohler Generator Issues

[boB Gudgel]

Nick Soleil wrote:

Hi Jeff:
I have had some similar issues with the Kohler generators in 
recent years, after installing hundreds of air cooled and water cooled 
generators from them.  I have heard that they are less reliable now, 
and the company is harder to deal with now.
Recently, I tried a Generac in an off-grid project, which I have 
found is even more difficult to work with.  They don't warranty the 
product for off-grid applications, it requires hard wiring a battery 
charger, and it starts and stops based on utility sensing, which 
required installation of a relay to switch the sensing circuit on and 
off.  It was a pain to deal with, and required a few more trips to the 
site than I would have liked.
On a similar note, Xantrex provided the Auto Gen Start module, but 
it did not support 2-wire start!  Isn't that the most common gen start 
configuration?  The newer versions do offer that now.
 



Is this "no warranty if used off grid" in writing from these 
manufacturers, or is it just some salespeople saying this ?


Why would you need a generator if you have grid available ?

boB





Nick Soleil
Project Manager
Advanced Alternative Energy Solutions, LLC
PO Box 657
Petaluma, CA 94953
Cell: 707-321-2937
Office: 707-789-9537
Fax: 707-769-9037



*From:* Jeff Yago 
*To:* RE-wrenches 
*Sent:* Mon, March 29, 2010 7:53:18 AM
*Subject:* Re: [RE-wrenches] Kohler Generator Issues


Although we have specified and included Kohler RES models in all our 
off-grid and battery based solar projects for over 15 years, we have 
seen a real decline in the suitability of the Kohler line in the past 
few years for use in solar/battery/generator applications.  First they 
killed off the 1800 RPM units under 15 kW.  We had many older systems 
that would not work when we replaced an aging 1800 RPM unit with their 
same kW size new 3600 RPM units, which made inverters go nuts with 
under-voltage and over-current errors.


Then several years ago they got rid of the battery charging alternator 
or whatever that re-charged the battery when the generator was running 
as a way to reduce costs, so now the only way to keep the battery 
charged was to plug in a full time float charger. This 24/7 electrical 
load is not a good idea for smaller off-grid systems and requires 
another set of wires out to the generator to supply this outlet.  
Finally, Kohler added a diagnostic electronics panel that adds another 
24/7 electrical load.  We "kill" this off during installation on any 
off-grid application as we cannot justify this 24/7 standby load.  
There is a software switch to do this, but its not easy to find in the 
instructions.


Funny thing was the other day I received a call from the main Kohler 
factory about some marketing issues and I finally let loose with the 
above rant.  I really complained that so far they have done everything 
they could NOT to serve this very large and growing off-grid market, 
and I pointed out that most of their recent design "improvements" made 
their generators LESS suitable for this market, not better.  This guy 
was absolutely dumb-struck, and it appears to me that they have made 
no effort to understand this market.  Their more recent efforts to 
void warranties is just another reason to look for a different 
generator supplier.


Has anyone on this list had any contact from Kohler central office 
about finding out what features this industry needs?  The guy I talked 
with may be just blowing smoke, but he promised to have a followup 
call in next few weeks to learn more about what they can do.  
According to him, he thinks they can add a software "switch" in the 
programming for little or no cost like "on/grid - off/grid" that we 
could access during setup that would adjust generator parameters and 
standby losses when used in an inverter-battery application.  In case 
he really does followup, are there any other rants I could include 
from you guys that have been a problem for you when using Kohler 
generators.  I will assume we are limiting this to their non-water 
cooled units under 15 kW.


While ranting on generators, the main reason we liked to use Kohler 
was the easy 2-wire start/stop connections you can connect to the aux 
relay in most inverters, while many other generator brands were not 
easy to remote start from an inverter or required multi-step starting 
relays.  Has this changed, and are there now other brands of 
generators in the 8 to 15 kW range that work well for backup of 
solar/battery charging applications and the manufacturer does not have 
warranty issues when used in off-grid applications?


Thanks,

Jeff Yago

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Re: [RE-wrenches] Kohler Generator Issues

[boB Gudgel]

Jason Szumlanski wrote:

Bob,

I guess you don't live in a hurricane prone area! Grid-tied or off-grid,
backup generators are common in this neck of the woods.
  

Yes, of course, Jason.
But, wouldn't it  be more of a generator "run time" issue ??
After all, the grid isn't really there when the power is out... is it ?

I guess that's subject to interpretation.  We deal with generator 
installations
so I would still like to know if there is something in writing or if it 
has been only verbal
at this point.  Something sounds fishy to me.   Oh, and 3 tubs of tartar 
with that fish, please.


Thanks guys.
boB




Jason Szumlanski
Fafco Solar
Southwest Florida

Original Message
Message: 3
Date: Tue, 30 Mar 2010 12:07:28 -0700
From: boB Gudgel 
To: RE-wrenches 
Subject: Re: [RE-wrenches] Kohler Generator Issues
Message-ID: <4bb24bf0.7000...@midnitesolar.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowe

Is this "no warranty if used off grid" in writing from these 
manufacturers, or is it just some salespeople saying this ?


Why would you need a generator if you have grid available ?

boB



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