Re: [RE-wrenches] USE-2 in white?

[Dave Click]

I've seen it in the field from this manufacturer:
http://www.kristechwire.com/use-2-solar-wire.php

 Original Message 
Subject: Re: [RE-wrenches] USE-2 in white?
From: EcoSolar - Eric Andrews 
To: 'RE-wrenches' 
Date: 2010/8/2 12:32


YES.  We get ours from PLATT Electric.  Most electric supply houses
should have this wire. It is definitely nice for your DC source circuits.

Eric R. Andrews

NABCEP Certified PV Installer

Eco Solar, Inc.

Electrical Contractor #C623

www.ecosolarnow.com

PO Box 5194

Klamath Falls, OR 97601

541-281-8252 cell

541-273-3200 office

mailto:e...@ecosolarnow.com 

/Saving the World... One Solar Panel at a Time!/



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Re: [RE-wrenches] minimum service

[Dave Click]

230.79(C):

230.79 Rating of Service Disconnecting Means.
The service disconnecting means shall have a rating not less than the 
calculated load to be carried, determined in accordance with Part III, 
IV, or V of Article 220, as applicable. In no case shall the rating be 
lower than specified in 230.79(A), (B), (C), or (D).
(A) One-Circuit Installations. For installations to supply only limited 
loads of a single branch circuit, the service disconnecting means shall 
have a rating of not less than 15 amperes.
(B) Two-Circuit Installations. For installations consisting of not more 
than two 2-wire branch circuits, the service disconnecting means shall 
have a rating of not less than 30 amperes.
(C) One-Family Dwellings. For a one-family dwelling, the service 
disconnecting means shall have a rating of not less than 100 amperes, 
3-wire.
(D) All Others. For all other installations, the service disconnecting 
means shall have a rating of not less than 60 amperes.


 Original Message 
Subject: [RE-wrenches] minimum service
From: Marco Mangelsdorf 
To: 'RE-wrenches' 
Date: 2010/8/27 01:41


I believe that there’s a section the code that states that a residence
shall have a minimum 100A service.

Can anyone tell me where that is?

Thanks,

marco



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Re: [RE-wrenches] DC Discos for Enphase

[Dave Click]

In John's white paper on wiring Enphases:
http://www.nmsu.edu/~tdi/Photovoltaics/Codes-Stds/WIRING%20ENPHASE%20MICROINVERTERS-11.pdf

he recommends covering the module first anyway so the load-break 
disconnect isn't really an issue. Since you're at the module anyway to 
disconnect that module from the inverter, this usually isn't too hard. 
In the same article he mentions that CSA approved the dc input 
connectors at the microinverter as load-break rated disconnects. I 
believe that Enphase has stated all of this as well but this is the only 
link I know of (I'm sure they have something more up to date):

http://www.enphaseenergy.com/downloads/NEC_EnphaseCheatSheet.pdf

DKC

 Original Message 
Subject: [RE-wrenches] DC Discos for Enphase
From: solar...@aol.com
To: re-wrenches@lists.re-wrenches.org
Date: 2010/9/14 13:18


Howdy Wrenches:
I don't try to stir things up, but I was just wondering last night as I
fell asleep reading the latest issue of HomePower magazine (# 139), if
anybody else caught a chill when they read this in the Code Corner
(highlighted in a box):
"Both microinverters and microinverters attached to PV
modules in the field or in the factory that have any exposed
DC single conductor cables are required to meet all of the
NEC’s DC wiring requirements. These may include Section
690.5 ground-fault detector requirements, DC and AC
disconnect requirements (potentially handled by connectors
listed as disconnects), and inverter DC grounding-electrode
requirements."
- John Wiles
Which begs the question: Are  module connectors currently listed as
disconnects?
As well as: If DC voltages for each disconnect are less than 48 V, would
a simple switch suffice, should the poor hapless installer run into an
AHJ with OCD?
Patrick A. Redgate
*/AMECO Solar, Inc.
Serving Solar California
Since 1974
7623 Somerset, Blvd.
Paramount, CA 90723
562-633-4400
/*//www.solarexpert.com _
www.amecosolar.com 

_



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Re: [RE-wrenches] Delta LAs

[Dave Click]

On my own system I have a DC suppressor from
http://www.surgesuppression.com/

It's UL listed with a 25-year warranty. Not as cheap as a Delta (or 
Citel as far as I know) though, but I felt a lot more confident with 
this given our crazy lightning storms in FL.


DKC

 Original Message 
Subject: Re: [RE-wrenches] Delta LAs
From: Mick Abraham 
To: RE-wrenches 
Date: 2010/9/14 15:17


Citel products do have a listing mark but this is European style CE, not
American style UL/ETL. Citel is reputedly working on American
certification but one would be advised to not hold one's breath.

The Citel products which mount to a DIN rail have an LED indicator which
goes dark once the surge elements have been sacrificed. Also some of
their units have an auxiliary switch which can remotely indicate a blown
condition. This is in the form of dry contacts..a normally open and a
normally closed one, so various indicator circuits can be designed
around that. The contacts have a low amp AC rating and also a (lower
amp) DC rating but I do not remember the numbers at present.

Jolliness,

Mick Abraham, Proprietor
www.abrahamsolar.com 

Voice: 970-731-4675


On Tue, Sep 14, 2010 at 12:43 PM, R Ray Walters mailto:r...@solarray.com>> wrote:

You could buy several ground rods for the cost of one Delta.
Ground Impedance is the real issue. Both the Delta and the
Polyphasor need a good ground to work.
While I haven't seen much of a correlation between Deltas and
reduced lightning damage, (lots of system damage with and without)
I have found that well grounded systems (tied to a steel cased well)
have never had a problem, even with direct strikes to a wind turbine
(did lose the $40 turbine rectifier, but nothing else)

I now own a clamp-on ground impedance tester, and the results were
miserable. Some electrodes were over 800 ohms to ground! (code
requires under 25 ohms)
I'd spend more time and money reducing ground impedance, and then if
it makes you feel good inside, throw the little "lightning faeries"
in, if the AHJ isn't looking...

If its really lightning country, and a really expensive off grid
system, I use Polyphasor, but they have their own issues. (very
expensive, no UL listing, loose internal connections, nuisance
tripping, need a large J-box to mount them inside, etc.)
I haven't tried the Citel stuff, but it looks to be listed, and
mounts on a DIN rail. After installing a couple hundred Deltas, I'd
try something else at this point.


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




On Sep 14, 2010, at 10:22 AM, Kristopher Schmid wrote:


My thought here is that nothing will protect the equipment from a
direct strike, but a near strike that may induce a significant
surge may be absorbed by the LA and protect the equipment.  I like
the feedback so far.  It would not break my heart to stop using
them altogether.:-}
Kris

Legacy Solar
864 Clam Falls Trail
Frederic, WI 54837
715-653-4295
sol...@legacysolar.com 
www.legacysolar.com 

-Original Message-
*From:* re-wrenches-boun...@lists.re-wrenches.org

[mailto:re-wrenches-boun...@lists.re-wrenches.org
] *On Behalf
Of *August Goers
*Sent:* Tuesday, September 14, 2010 10:39 AM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] Delta LAs

All -
I guess my thought is a little off topic, but are lightning
arrestors even worth using at all? My logic has always been
that if lightning does indeed strike that it's likely going to
blow the arrestor and and inverter. We don't have much of a
lightning issue issue in the Bay Area so I don't have any
direct experience.
Best,
August

On Tue, Sep 14, 2010 at 6:29 AM, Kristopher Schmid
mailto:sol...@legacysolar.com>> wrote:

It is quite ironic that just a week after I posted a
question to the group
on testing the integrity of lightning arrestors, I had one
apparently faulty
out of the box.  The manifest of this was interesting:
when the AC LA
(LA302R) was connected in parallel on the AC input to a
SB3000 inverter,
there was 125vac neutral to L1, 125vac neutral to L2, and
1Vac L1 to L2.
SMA tech support suggested the LA as the issue and sure
enough, it was.
Attempting to test good and faulty arrestors with an
ohmmeter gave the same
result - off scale open.

Any thoughts or comments from the group?

Kris Schmid

Re: [RE-wrenches] Accessable?

[Dave Click]

And more specifically:
690.34 Access to Boxes.
Junction, pull, and outlet boxes located behind modules or panels shall 
be so installed that the wiring contained in them can be rendered 
accessible directly or by displacement of a module(s) or panel(s) 
secured by removable fasteners and connected by a flexible wiring system.


Andrew Truitt wrote:



Benn - I like installing j-boxes under the array as a general rule both
for aesthetics and to keep them somewhat sheltered from the elements.  I
do not see any code issues with the location because, as you mention,
they are still accessible.


 From NEC2008 Article 100:

*Accessible (as applied to equipment)*. Admitting close
approach; not guarded by locked doors, elevation, or other
effective means.

*Accessible (as applied to wiring methods)*. Capable of
being removed or exposed without damaging the building
structure or finish or not permanently closed in by the structure
or finish of the building.



- Andrew




On Wed, Sep 15, 2010 at 3:15 AM, benn kilburn mailto:b...@daystarsolar.ca>> wrote:

Wrenches,
There has been some mention on this list lately of locating Soladeck
and/or other combiner boxes under arrays.  This has me wondering if
folks are doing this only for a cleaner looking roof array or if
there are other reasonable intentions (lack of available roof space).

Other than a cleaner look, i see no benefit to doing this. (don't
get me wrong, a cleanly installed array is something to be proud of)
  However if the box ever needs to be accessed, you have to remove
at least one module to get to it, dealing with the whole 'breaking
the bond' issue; having to remove the module, replacing the WEEB
clip or undoing and then re-torquing the lug set screw,
re-installing module, etc.  If you just wanted to quickly check
something in the box (voltage, torque, whatever) it is no longer a
quick and easy task.

So the Canadian Electrical Code says in Section 0.Definitions

_Accessible_ (as applied to equipment) - admitting close approach
because the equipment is not guarded by locked doors, elevation, or
other effective means.

_Accessible_ (as applied to wiring methods) -
(a) not permanently closed in by the structure or finish of the
building; and
 (b) capable of being removed without disturbing the
building structure or finish.

My interpretation here is that;
(a) the box is not 'permanently closed in', just inconveniently
closed in. and,
(b) you are not disturbing the structure or finish, as you will be
replacing the module as soon as you are finished in the box.

Many pieces of equipment and/or panels require that you remove a
single piece or a multi-piece cover to access the wiring.  The pv
module is like a large 'cover' in this case. So i do not see this as
a code violation.  Do you?

I'm not familiar with the NEC, is it's definition of 'accessible'
similar to the CEC's?

Is this combiner mounting location under the array common practice
for some of you, or only done when roof space for a combiner box is
limited?

I am going to run this scenario by one of our inspectors, i just
thought i'd get some feedback from other Wrenches first.

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



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--
"Don't get me wrong: I love nuclear energy! It's just that I prefer
fusion to fission. And it just so happens that there's an enormous
fusion reactor safely banked a few million miles from us. It delivers
more than we could ever use in just about 8 minutes. And it's wireless!"

~William McDonough



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Re: [RE-wrenches] Delta LA's in or out? It's our choice.

[Dave Click]

I just remembered that I've seen Deltas pre-installed (by the factory) 
within Satcons- at least the 50s, and I think they're in the 250s as 
well. I guess they'd look a bit weird sticking out of the cabinet!


Dave Palumbo wrote:

Bill,

I checked with Delta and they say the LA’s are designed to be mounted
inside, or, outside the box. On their product sheets that came with the
arrestors in years past they clearly showed the LA’s inside the load
center. In fact that is the way they are still showing them used on
their sales web site http://www.deltasurgeprotectors.com/home.cfm

Maybe the lawyers want them shown in the box for liability concerns. The
tech person I spoke with says they recommend putting them in the box if
they are around combustible material such as insulation. Could that also
be dry grass around a ground mount?

They did say that on LA’s manufactured 2009 and later that the jar no
longer cracks, they have a “VIP plug” on the bottom of the jar that pops
out when the LA is done. They did say that on big, close by strikes, all
bets are off on just the VIP plug popping out. Expect more damage in
that case.

BTW, great article in Solar Pro on PV array voltage issues.

Thanks,

Dave

*From:* re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of *Bill
Brooks
*Sent:* Thursday, September 02, 2010 12:46 PM
*To:* 'RE-wrenches'
*Subject:* Re: [RE-wrenches] Delta LA's

David,

They are supposed to be mounted outside boxes so that you can clearly
see when they have been used up. Sand makes glass that expands and
breaks the plastic. They used to be porcelain for the very same reason.
If you are concerned about unqualified people coming in contact with
conductors, put a guard around it.

Bill.

*From:* re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of *Dave
Palumbo
*Sent:* Wednesday, September 01, 2010 5:32 PM
*To:* 'RE-wrenches'
*Subject:* Re: [RE-wrenches] Delta LA's

I am concerned with Delta LA 600VDC cans being mounted exterior from
J-boxes (or disconnect switches) on ground mounts.

I remember hearing from an old hand that these devices can fail in a
manner that could possibly expose the wiring to human hands. The wires
would have high voltage DC potential. Not something we need in our industry.

Am I worrying about something that can’t happen? Or should these be in
PVC boxes?

David Palumbo

Independent Power LLC

Offices in Lamoille and the Champlain Valley, Vermont

802.888.7194

www.independentpowerllc.com

NABCEP Certified Solar PV Installer™

Vermont RE Incentive Program Partner

*From:* re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of *North
Texas Renewable Energy Inc
*Sent:* Tuesday, August 31, 2010 10:07 PM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] Testing LSAs

For the first time since 2004 we got a residential PV red tag for
non-listed surge supressors. I just took them off and replaced them
after we got the green tag. Of course he also red-tagged the copper
ground plate because it was not thick enough. Go figure

Jim Duncan

North Texas Renewable Energy

-Original Message-
*From:* re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org]*on Behalf Of
*Andrew Truitt
*Sent:* Tuesday, August 31, 2010 8:09 PM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] Testing LSAs



Question: Since the Delta lightning arrestors are not UL Listed, do
they threaten the UL compliance of the PV system as a whole?


- Andrew Truitt
Currently of Standard Solar
Free agent in the Denver area as of 10/6/10

On Tue, Aug 24, 2010 at 6:02 PM, Peter Parrish
mailto:peter.parr...@calsolareng.com>> wrote:

I would think that an ohmmeter set to the 10 Mega-ohm setting (or the
highest setting possible), would be the first test. I would like to see
something on the order of 750 k-ohms (3/4 of a mega-ohm).

But the system should be tested at a higher voltage, than that available
from a DMM. Apply 240 Vac and measure the RMS current. It should be
should
be 0.3 mA or less.

Finally, these puppies really need to be tested at much higher voltages,
perhaps someone knows how to use that megohmmeter to test? What does the
manu recommend, “if suspect, throw it away and buy a new one”?

- 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

Re: [RE-wrenches] GEC for Enphase inverters

[Dave Click]

I'd worry about putting such a high current in anyway- Enphase's max 
input is 10A (max Isc 12A) while the Evergreen Imp is 11.69 for their 215W.


 Original Message 
Subject: Re: [RE-wrenches] GEC for Enphase inverters
From: Nick Soleil 
To: RE-wrenches 
Date: 2010/9/16 10:58


Thanks Jay:
That is true. Enphase and Evergreen are not compatible.
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:* jay peltz 
*To:* RE-wrenches 
*Sent:* Wed, September 15, 2010 4:48:22 PM
*Subject:* Re: [RE-wrenches] GEC for Enphase inverters

Hi Nick,

Last time I checked Evergreen modules don't work with positive ground
systems.

jay

peltz power
On Sep 15, 2010, at 9:19 AM, Nick Soleil wrote:


Yes, Enphase bonds the DC positive to ground in their inverters. This
allows them to work with all modules, including SunPower.
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] SolarWorld 245

[Dave Click]

I believe this is saying that after the initial LID (Light Induced 
Degradation), it will be rated at no less than 97% of STC. AFAIK, LID is 
easily a percent or two on most modules. These modules will have been 
tested to produce at least their rated output when they leave the 
factory, before they see sunlight.


 Original Message 
Subject: Re: [RE-wrenches] SolarWorld 245
From: Kent Osterberg 
To: RE-wrenches 
Date: 2010/10/13 15:22


Marco,

There was a time in the near past when +/- 10% meant that every module
shipped was at least -5%. Things have improved.
The copy of the SW 245 spec sheet that I just downloaded has a red note
explaining that every module is above nominal in their flash test. The
+/- 3 tolerance may be largely uncertainty in the accuracy of the flash
test equipment, procedures, and in how the flash test correlates to the
real world. In other words it is a CYA operation.

Kent Osterberg
Blue Mountain Solar


Marco Mangelsdorf wrote:


SolarWorld is pushing hard its 245-watt module with the claim that it
has won the Photon mag module competition in 2008 and 2009 (compared
to several other manufacturers).

I can send the spec sheet to anyone who wants it. It states on the
front page: SolarWorld only delivers modules that have */greater than
or equal to the nameplate rated power/*. (emphasis added)

This implies clearly to me a minus zero percent power tolerance.

And then you look at the finer print on page 2 and see under *Power
Tolerance : +/- 3%**

*Only modules with flash-tested > or = Pmax are delivered. Linear
warranty guarantees Year 1 module output to > or + 97% or Pmax.

I’m confused. Does this mod actually have a -0 PT or not?

And on another note, are many of you finding it difficult to get an
adequate supply of PV mods to meet your demands these days?
SolarWorld, Schott, Sharp and Kyocera seem to be in short supply these
days out in these here parts.

Thanks,

marco




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Re: [RE-wrenches] Ground Mount Screening

[Dave Click]

How about hardware cloth along the back of the array beneath the rails? 
I think that's been suggested on this list before.


 Original Message 
Subject: [RE-wrenches] Ground Mount Screening
From: Drake 
To: RE-wrenches 
Date: 2010/10/21 12:34


Hello Wrenches,

We are installing a ground mount system with Enphase inverters. 690.31
requires readily accessible source and output conductors OPERATING at
over 30 volts to be installed in a raceway. The Vmp of the REC230PE
modules is 29.4 volts. Of course it would go higher in cold weather. Do
I have any argument that would allow us to not install the DC conductors
in a raceway?

The NEC Handbook comments "Most PV modules do not have provisions for
attaching raceways. These circuits may have to be made "not readily
accessible" by use of physical barriers such as wire screening".

I have heard of a green screening material that has been used on the E,
W and N sides of ground mounts to render the area not readily
accessible. Does anyone know what this is? What else would work that
would be more cost effective than running a chain link fence around the
array?

Thanks,

Drake
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Re: [RE-wrenches] Head Spinning..(Con) fused.

[Dave Click]

Fronius IG Plus on the spec sheet also specs "Max. continuous utility 
back feed current" as 0A.


 Original Message 
Subject: Re: [RE-wrenches] Head Spinning..(Con) fused.
From: William Miller 
To: RE-wrenches 
Date: 2010/11/14 12:54


Darryl:

If Aurora can not verify that their inverters will not backfeed the DC
circuitry, then the circuits must be fused. This too is specified in
Berdner's study. We are in agreement.

I think SMA is not the only transformer inverter with a no-backfeed
declaration.

William



At 05:48 AM 11/14/2010, you wrote:

I never thought I would disagree with William, I have the highest
admiration for him,
But the transformerless inverter has no seperation between grid and
array, no problem if everything is fused.
Darryl
--- On *Sat, 11/13/10, William Miller //* wrote:


From: William Miller 
Subject: Re: [RE-wrenches] Head Spinning..(Con) fused.
To: "RE-wrenches" 
Date: Saturday, November 13, 2010, 11:26 PM

Eric:

The best resource I have found on this subject is the white paper
that John Berdner wrote. I have a copy on my web site:
millersolar.com under Resources.

The general rule is no system with two strings combined needs fuses.
Run the calcs as presented in the white paper for verification.

Just because circuits share a J-box or conduit is not a reason to
fuse. Actual connection into an inverter is required before the
number of strings is tabulated.

William Miller




At 08:40 PM 11/13/2010, you wrote:

Wrenches,

Can anyone shed guidance on the following for me? Should these
strings be fused:

Total Modules: 44
Total Strings: 4 strings of 11
Total Inverters: 2

Modules: Silicon Energy 195 Watt @ 8A
Each string feeding an independent MPPT input on an Aurora PVI 4.2kW
Inverter (there are 2 / Aurora)
Inverter is transformerless (READ 690.35 (B))

Each strings passes through a shared SolaDeck jbox, no combining,
and head directly to their own dedicated GE THN2261RDC DC Disconnect
before entering a dedicated MPPT input on the inverter.

My big question is 690.9 (A) exception (b) which states I don't need
ocpd as long as "The short circuit currents from all sources do not
exceed the ampacity of the conductors."

Because all four strings pass through the same jboxs and conduit
before reaching their disconnect and could potentially short
together, should I fuse each string?

Or am I just up too late reading code?

Thanks for being a resource.

--
Eric Thomas
Solar Epiphany LLC
(206) 919-3014
www.solarepiphany.com 

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Re: [RE-wrenches] outdoor disconnects on multiple buildings

[Dave Click]

I think that if you have the 705.10 directory showing the disconnect 
locations (a directory at each location), you'd be OK per NEC. I think 
this question is likely one to ask your utility- the language may be in 
your interconnection agreement and you likely already know how flexible 
utilities aren't when it comes to minor changes to their interconnection 
agreement... I imagine that the utility would require you to have an 
additional 5kW PV disconnect there at the service entrance, adjacent to 
the 20kW disconnect, but that they wouldn't require you to combine them 
into a single disconnect. Maybe it would still make sense for you to do 
that- since I imagine you have a combining panel in the main building, 
why not bring the 30A breaker from the out building and land it in that 
panelboard with the 15A breakers from the 20kW?


FYI, Jeff Sargent at the NFPA doesn't consider PV to be a separate 
service based on "the permission to connect a PV system on the line side 
of the service disconnecting means per 230.82(6)." So with this, these 
two wouldn't count against the maximum six disconnects- just in case 
that's an issue you're running into as well.


Hope that helps.
DKC

Kirk Herander, VSE wrote:

Hello,

I’m working on a system which will have 5 kw on an outbuilding and 20kw
on the main building, all Enphase inverters, I plan to put an AC disco
for the 5kw on the outside of its building and another on the outside of
the main building for the 20 kw array. Both arrays feed into the main
panel in the main building. But now I’m wondering if I might have to
combine the 5kw and 20 kw outputs so the outdoor disco on the main
building shuts both arrays off. Any ideas here? I don’t think the code
addresses this clearly.

Kirk Herander

VermontSolar Engineering

802.863.1202

NABCEP(tm) Certified Solar Installer

NYSERDA-eligible Installer

VT Solar Incentive Program Partner



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Re: [RE-wrenches] Code reference needed

[Dave Click]

At a Xantrex training once upon a time, they explained that the three 
foot minimum height was to keep the unit out of reach of a typical lawn 
sprinkler. I don't know of an NEC reference for any minimum height required.


Peter Parrish wrote:

I spent some time putting together information on the "2'-6" Lower Limit"
and the "6'-6" Upper Limit" for operable equipment; and then when I went to
send out the results of my efforts, the content in the email disappeared.
Since the information I thought would be helpful, I have re-assembled the
information. I also found the 6" depth of working space citation. Here goes.


First, there has been a pretty complete move to metric units in the NEC
a/k/a "SI or metric Units". In some places in the NEC, distances are defined
in terms of meters and decimal fractions of meters, in other places they are
defined in terms of millimeters, and in some others, they remain defined in
terms of feet and inches. So the oft mentioned 6'-6" (1.98 meter) limit has
occasionally been redefined to be 2.0 m (or 6'-6.7" and rounding up becomes
6'-7"). However, in many other sections of the NEC designates 2.0 m as 6-1/2
ft; go figure.

600 V or less:

Height of working space (headroom) is 2.0 m (6-1/2 ft) or height of
equipment. Reference is 110.26(A)(3) "Height of Working Space", which in
turn refers to 110.26(E) "Headroom", with some exceptions.

Depth of working space 150 mm (6 in.). Reference is 110.26(A)(3) "Height of
Working Space".

Overcurrent Protection needs to be "readily accessible" and the "center of
the grip of the operating handle" be no more than 2.0 m (6'-7"). Reference
is 240.24(A).

Switches: "center of the grip of the operating handle" be no more than 2.0 m
(6'-7") above floor or working platform. There are some exceptions for fused
switches and circuit breakers on busways, motor switches; and there is a
exception for "Hookstick operable switches".

Inverters. I have data on SMA, Xantrex and Fronius.

SMA: The Sunny Boy must be mounted so that there is at least eight inches of
clearance around the Sunny Boy. The clearance between the inverter or the
SMA DC-Disconnect (if applicable) and the ground has to be at least 3 ft.
Sunny Boy Installation manual (Ver. 2.2, 2008) p. 26.

Xantrex: Table 2-2 Inverter Clearance Requirements Location Minimum
Clearance
Above 300 mm (12 inches) Below There is no clearance requirement between the
bottom of the inverter and the ground. Front 300 mm (12 inches) minimum. 910
mm (36 inches) are recommended for easy access for reading the display,
avoiding accidental contact with hot surfaces, and servicing the inverter.
Sides Units can be mounted side by side with no clearance between them, but
150 mm (6 inches) of clearance around the outside edges of the outermost two
units is recommended. In hot climates, some clearance between units may be
needed to prevent thermal derating. Xantrex Grid Tied Owner's Manual,
December 2009, Revision D, p. 2-7.

Fronius: To get the most out of your FRONUS IG unit, observe the following
rules... Only install it on a solid vertical wall at a minimum of 3 ft. (0.9
m) above
the ground and to a maximum of 6.5 ft. (2 m). Operating instructions
Grid-connected inverters for photovoltaic systems 02/2008.

I, too, can't find the 2'-6" lower limit specified anywhere in the NEC 2008.

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


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Re: [RE-wrenches] Tranformless inverter

[Dave Click]

I believe it's just:
Fusing on the +/-
disconnects break both + and -
Need your modules to use PV wire
labeling per 690.35(F)

Square D discos are UL'd for ungrounded systems- and I just noticed that 
there's a June 2010 revision of the Square D disconnect guide. A bit of 
clarification since the 9/09 edition I had.

http://ecatalog.squared.com/pubs/Electrical%20Distribution/Safety%20Switches/Solar%20Disconnect%20Switches/3110DB0401.pdf

August Goers wrote:

Hi Bill and Wrenches -

For ungrounded arrays what specific fusing and or DC disconnect
requirements are needed compared to grounded arrays?

I'm trying to sort through the code but nothing is popping out at me
besides what was already mentioned about needing to disconnect both the
positive and negative lines on the DC side. In SMA's case I'm guessing
that their new transformerless inverters with integrated DC disconnects
and fuses may already take of all the requirements?

Best,

August

August Goers

Luminalt Energy Corporation

1320 Potrero Avenue

San Francisco, CA 94110

m: 415.559.1525

o: 415.641.4000

aug...@luminalt.com 

*From:*re-wrenches-boun...@lists.re-wrenches.org

[mailto:re-wrenches-boun...@lists.re-wrenches.org
] *On Behalf Of *Bill
Brooks
*Sent:* Friday, October 01, 2010 8:29 AM
*To:* 'RE-wrenches'
*Subject:* Re: [RE-wrenches] Tranformless inverter

All,

Transformerless inverters are simply a subset of ungrounded or
resistively grounded PV systems covered by the NEC in 690.35 since the
2005 code cycle. Power-One has been marketing their ungrounded inverter
in the U.S. for several years now. It was listed by CSA. The
requirements for ungrounded systems in 690.35 are as follows:

•“Photovoltaic power systems shall be permitted to operate with
ungrounded photovoltaic source and output circuits where the system
complies with 690.35(A) through 690.35(G).

−*(A) Disconnects. *All photovoltaic source and output circuit
conductors shall have disconnects complying with 690, Part III.

−*(B) Overcurrent Protection. *All photovoltaic source and output
circuit conductors shall have overcurrent protection complying with 690.9.

−*(C) Ground-Fault Protection. *All photovoltaic source and output
circuits shall be provided with a ground-fault protection device or
system that complies with (1) through (3):

•(1) Detects a ground fault.

•(2) Indicates that a ground fault has occurred

•(3) Automatically disconnects all conductors or causes the inverter or
charge controller connected to the faulted circuit to automatically
cease supplying power to output circuits.

−*(D) *The photovoltaic source and output conductors shall consist of
the following:

−(1) Nonmetallic jacketed multiconductor cables

−(2) Conductors installed in raceways, or

−(3) Conductors listed and identified as Photovoltaic (PV) Wire
installed as exposed, single conductors.

−*(E) *The photovoltaic power system direct-current circuits shall be
permitted to be used with ungrounded battery systems complying with
690.71(G).

−*(F) *The photovoltaic power source shall be labeled with the following
warning at each junction box, combiner box, disconnect, and device where
the ungrounded circuits may be exposed during service:

WARNING

ELECTRIC SHOCK HAZARD

THE DC CIRCUIT CONDUCTORS OF THIS

PHOTOVOLTAIC POWER SYSTEM ARE

UNGROUNDED AND MAY BE ENERGIZED

WITH RESPECT TO GROUND DUE TO

LEAKAGE PATHS AND/OR GROUND FAULTS.

−*(G) *The inverters or charge controllers used in systems with
ungrounded photovoltaic source and output circuits shall be listed for
the purpose.

We now have several products newly on the market to include on the list
such as the SMA and Exeltech products. Ungrounding the array requires
additional fusing and disconnects, but the most significant difference
is that the module wiring and all external cable must be PV Wire/Cable.
Therefore only modules with PV Wire/Cable can be used in these systems.
You must confirm from the manufacturer that they have made the switch.
Hopefully all manufacturers will be installing PV Wire/Cable soon so
that this will not be a problem anymore.

It is a good call to use up your USE-2 and order PV Wire/Cable from now on.

Bill.

*From:*re-wrenches-boun...@lists.re-wrenches.org

[mailto:re-wrenches-boun...@lists.re-wrenches.org
] *On Behalf Of *Exeltech
*Sent:* Friday, October 01, 2010 6:39 AM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] Tranformless inverter

Transformerless grid-tie inverters are permitted under the National
Electric Code as of 2008. The Nationally Recognized Testing Laboratories
(UL, ETL/Intertek, CSA, etc.) took a while to develop the testing
procedures for testing to UL1741, which was the basis for most of the delay.

SMA isn't the only company with transformerless grid-tie inverters. I
know

Re: [RE-wrenches] PV wire/double insulated

[Dave Click]

690.35 (D)  The photovoltaic source conductors shall consist of the 
following:

(1) Nonmetallic jacketed multiconductor cables
(2) Conductors installed in raceways, or
(3) 	Conductors listed and identified as Photovoltaic (PV) Wire 
installed as exposed, single conductors.

***

As soon as you enter a raceway, you can do whatever you like! THWN-2 is 
just fine.



Marco Mangelsdorf wrote:

I’m starting to use the SMA SB transformerless 8-10 kW inverters.

It appears that the new SMA 6-circuit combiner box is being included
whenever I order one of these buggers (at least from my distributor).

Does the double insulated PV wire have to be used all the way back to
the inverter? Or can I get by with just using it to the combiner and
then transition to the usual TWHN-2 wire?

Thanks,

marco



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[RE-wrenches] Handy Map for ASHRAE temperatures

[Dave Click]

Hi all,

My awesome coworker James converted the ASHRAE temperature data in the 
back of the Solar ABCs expedited permitting guide from a spreadsheet 
into a map format. Thought I'd run it by the list to see if there are 
any changes you'd recommend (probably best if you reply to me off-list). 
If you zoom out too far, it takes a while for the map to load- and since 
I'm sending this out to 300 people (or whatever) it may be a bit slow 
for all of you who click this link at 11:10am ET today...

http://www.solarabcs.org/permitting/map/index.html

Hopefully this proves helpful for you when you're calculating VOCs in 
new geographical areas. Temperatures are all in degC.


Thanks,
Dave
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Re: [RE-wrenches] Federal ITC

[Dave Click]

The grant was just passed for 2011 as well:
http://www.seia.org/cs/news_detail?pressrelease.id=1181

The ITC continues through 2016/12/31, and nothing's changed for solar 
hot water.

http://www.dsireusa.org/incentives/incentive.cfm?Incentive_Code=US37F&re=1&ee=1

 Original Message 
Subject: Re: [RE-wrenches] Federal ITC
From: Dave Palumbo 
To: 'RE-wrenches' 
Date: 2011/1/4 10:42


Wrenches,

I’m looking for confirmation on the expiration dates on the Federal
Investment Tax Credit for businesses, as wells as the Individual Tax
Credit (or Personal Tax Credit) for individuals.

As I understand it the ITC Grant for businesses (money up front) expired
at the end of 2010.

However it is my understanding that the solar Tax Credit’s for both
business and individuals will continue through tax year 2016. Is that
correct?

And will Solar Hot Water continue to be treated the same as PV for the
ITC’s?

Thanks,

David Palumbo

Independent Power LLC

462 Solar Way Drive

Hyde Park, VT 05655**

*/www.independentpowerllc.com /*

NABCEP Certified PV Installer

Vermont Solar Partner

23 Years Experience, (802) 888-7194



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Re: [RE-wrenches] Xslent?

[Dave Click]

Short answer: no, this product's reactive power generation will not 
affect you in the real world.


Long answer:
I don't see how their 6kVA system could outperform your 10kW system 
unless you're installing your system in the shade. This device seems to 
be quite limited- max VOC 42VDC, max input wattage 200W, max input 
short-circuit current 10A! And it appears to not have an internal 
GFDI(!), nor power line carrier, so you're running separate ethernet 
cable between the inverters.


As for the reactive power, a larger portion of future inverters will be 
able to supply complex power rather than just real power. However, an 
important part of that feature is that it will be dynamic- when the 
utility (or site) needs more reactive power, it can ask the inverter to 
adjust its output. I can't find anything in the documentation on this, 
but it appears from the description that this company plans for you to 
measure your site power factor, and then manually set these inverters to 
a certain power factor (presumably lower than the site PF to help adjust 
the site PF in the right direction). I don't know how power factor 
penalties are typically calculated; for the utilities that do actually 
charge this (not all do), would they look at the worst 15 minutes of the 
month? If so, I think it's safe to say that a 6kVA system of these 
inverters- which is presumably capable of peaking at 6 kVAR during about 
three hours of a nice day- will have minimal impact on that power factor 
penalty. And since the user manual tells you not to install more than 
30kW at a single interconnection point... how much do they really think 
they're helping?


So, the reactive power feature of this product may be worthwhile if your 
site only has power factor problems from about 10-2, only on sunny days, 
and you are on your computer at the site continuously adjusting the 
inverters' PF to ensure you're not overcompensating and making your site 
PF worse, and your utility penalizes for power factor, and your building 
power draw maxes out below the size of your PV system. To be really 
useful, VARs from inverters need to be dynamically configurable by some 
sort of software control so that you are always helping your site PF, 
and those VARs also should be available 24-7... and if the utility 
offers to pay you for your VARs, then they will also require the 
inverters to respond to utility requests for VARs (right after a power 
outage, for example, when a bunch of motors are trying to come back up 
to speed). And for this to really happen, we'll need a revised UL 1741. 
Maybe in 2015.


My $0.03.
DKC

August Goers wrote:

Hi All -

Have any of you heard of the Xslent XPX-A1000 microinverter?

http://www.xetenergy.com/#Tab-2_link-1

We're going up against them on a 10 kW system and I'm trying to figure out
if their claims about producing reactive power mean anything to us in the
real world. They are saying that their 6 kW system will outperform our 10
kW system.

I also noticed that their CEC efficiency is only 89%...

Best,

August
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Re: [RE-wrenches] Xslent?

[Dave Click]

Standard residential utility meters couldn't care less about power 
factor and will ignore reactive power. Additional utility bill savings 
by using these reactive-capable microinverters is $0.


Dan brought up a good point that adding too much capacitance also hurts 
power factor- so even if a utility did start caring about residential 
power factor, they wouldn't want these devices on every house because 
then their feeders would become excessively capacitive when motors 
weren't running. IMHO reactive power from these devices only makes sense 
if it's configurable and dispatchable by either the utility or a 
building's energy management system. And it doesn't seem to be.



 Original Message 
Subject: Re: [RE-wrenches] Xslent?
From: Mark Frye 
To: 'RE-wrenches' 
Date: 2011/1/10 12:14


SMA now delivers large inverters that provide several options for power
factor correction provided by the output of the inverter.
So we are not talking about the viability of the technology. There may
still be a question of how well the technology is implemented in this
particular microinverter.
The main question here is the efficacy of claims of an advantage for
small residential customers such that reduced PV array sizes deliver
equivalent energy as metered by the local utility.
Having followed the the whole power factor correction device discussion,
I still have some question in my mind as to the resolution of the
question of whether or not standard residential utility meters will
measure and accure a credit for improved power factor.

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 *Exeltech
*Sent:* Monday, January 10, 2011 8:59 AM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] Xslent?

By the way, in answer to answer your original question, capacitors of
proper value, when installed in a circuit containing inductive loads,
are capable of allowing the circuit to attain a power factor of 1.0. As
part of our Underwriter's Laboratories testing for our grid-tied
inverters, a test fixture is used that's capable of both inductive and
capacitive reactance (it's part of the anti-islanding tests). I've
witnessed the power factor being adjusted from 0.7 leading and lagging
to an absolute perfect 1. (yes, four decimals). It's all done by
varying the value of capacitance in the circuit. Thus, if one were to
use lab-grade test equipment, and take the time needed to make such a
precision adjustment, it's possible to achieve absolute unity in an
inductive circuit by "tuning" it with a capacitive circuit.


Dan


--- On *Mon, 1/10/11, North Texas Renewable Energy Inc
//* wrote:


From: North Texas Renewable Energy Inc 
Subject: Re: [RE-wrenches] Xslent?
To: "RE-wrenches" 
Date: Monday, January 10, 2011, 8:29 AM


How efficient is a capacitor in offsetting the power factor error?
99.9%...±2%...?
Jim Duncan

-Original Message-
*From:* re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org]*on Behalf Of
*Exeltech
*Sent:* Sunday, January 09, 2011 9:03 PM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] Xslent?

--- On Fri, 1/7/11, Peter Parrish
 wrote:

>  What ever is done to reduce the reative power, it has to be done

>  in real time (with a fraction of 0.016 seconds, the 60 Hz cycle).

>  You can’t wait until later in the evening to solve a problem that

>  is occuring during the day.


Peter is absolutely correct. Power factor correction MUST occur
on a half-cycle by half-cycle basis, and at the exact moment of
power consumption by the reactive load. Anything else won't be
effective, and may in fact worsen the power factor at a given
point in the grid.


>  Real time compensation can be often done with capacitors alone

>  or in conjuction with some smart electronics. Remember that for

>  short periods of time capacitors can store considerable amounts

>  of energy and can smooth out these reactive currents.


Capacitors placed across a power line will store energy for
exactly one-half cycle. At that point, the polarity reverses,
the capacitor is discharged to to zero, then recharged to the
opposite polarity. This process repeats every cycle.

What DOES take place is a phase shift (displacement) in the
current flow relative to the voltage waveform. Power factor
correction is done with capacitor banks (we see them in
substations and on power poles) to offset the power factor of
the grid itself, which by its de

[RE-wrenches] IRC 2009

[Dave Click]

Hi all-

Does anyone have a copy of the 2009 International Residential Code? I 
only have the 2006. Please reply off-list. Thanks!


Dave
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Re: [RE-wrenches] Cable Sizing - revisited, Ambient Temp

[Dave Click]

John,

The 2% "ambient temperature" from ASHRAE is the appropriate starting 
point to use for these calculations. For some additional background I'll 
quote Bill:


**
ASHRAE bases its ‘warm‐season temperature conditions’ for each city on 
annual percentiles of 0.4%, 1.0% and 2.0%. As an example, the June 2.0% 
dry‐bulb design temperature for Atlanta is 91.7°F. Therefore, based on a 
30‐day month (i.e. 720 hours), the actual temperatures can be expected 
to exceed 91.7°F a total of 14 hours a month. The corresponding 1.0% 
design temperature (93.1°F) can be expected to be exceeded for 7 hours a 
month; while the 0.4% design temperature (94.6°F) can be expected to be 
exceeded for 3 hours a month (column 2).

**

In Jim Dunlop's example it sounds like he's starting with the summer 
ambient high (likely around 90F / 32C) and adding the 310.15(B)(2)(c) 
33C figure to reach the 61-70C range.


IMHO, ASHRAE 2% high temperature should be the "standard practice" for 
these conditions when calculating your base ambient temperature before 
additional adders. There are going to be site-specific conditions like 
your example where the conduits may heat up more than 310.15(B)(2)(c) 
requires; in that case I think you'd be on the right track to make your 
own field measurements to determine an appropriate temperature. In some 
cases the 10%/10ft rule may mean you can ignore short hot spots in the 
wire. If you had a situation where the conduit was in direct sunlight, 
plus light was being reflected off the roof and a light-colored wall 
behind the conduit, I suppose that would yield more heating than what 
the CDA study had found (http://www.iaei.org/magazine/?p=1743). I'm not 
sure that shooting an IR thermometer is the best option here; if you 
want to best replicate the study conditions, you may put a conduit 
section up on the roof in the desired location, put a temperature sensor 
in the conduit, and let it soak. Then compare that number with [ASHRAE 
2% + 310.15(B)(2)(c)] and pick the higher number. Or just add an 
additional 10C on top of ASHRAE+B2c and be done with it...


I think your plan of trying to measure the temperature 4" off the roof 
where the conduit sits, and then adding the additional 17C (or whatever) 
from the Table, will be too conservative; your initial measurement will 
be affected by some of the heating that's wrapped into the 
310.15(B)(2)(c) factor and you'd be double-counting that effect.


Hope that helps.
Dave

 Original Message 
Subject: [RE-wrenches] Cable Sizing - revisited, Ambient Temp
From: John Wadley 
To: RE-wrenches 
Date: 2011/1/22 02:40


Mr. Brooks,
You replied to Mr. Parrish back in 2009 with this example (below) on
properly applying all the deratings to ampacity for wire sizing. I have
a bit of confusion and a question about the definition of "ambient
temperature". You define it below as the ASHREA 2% high temp. My NEC
2008 (310.15 (2) Except No. 5 (3) (b) FPN) mentions it being an "average
ASHREA" number. The only definition for "ambient temp" in NEC I could
find was 310.10 FPN (1) which says it "varies along the length of the
conductor by time and place". In the Photovoltaic Systems by Dunlop, p.
288, he cites a sizing example without saying where ambient comes from
but uses 61C-70C (142F-158F) derate factor (0.58) for a sunlit roof top
conduit. He does not say how he arrives at that tempature range, but I
suspect he started with the 90F rating of the USE-2 conductor in the
example and added a Table 310.15 (B) (2) (c) adder of 33C. Other
articles I've read talk about conditions like an unventilated attic or a
sunlit jbox on a roof where ambient temps could reach 150F. I can also
think of a situation where on a flat roof with a surrounding parapet
wall, the sunlight shining into a corner would act like a solar oven on
any conduit running close to the corner. So, given all these definitions
and possible exceptions to the definition of "ambient temperature", does
your original definition (ASHREA 2% high temp) still stand as standard
practice for most conditions and are there situations where one should
use something other than that defined value? If one is unsure of an
exceptional situation, would it make sense to use an IR thermometer to
measure free air temp on a sunny, calm day and then the air temp exactly
where conduit might run and use the temp delta as an adder (like Table
310.15 (B) 2 (c)) to the ASHREA 2% high temp to arrive at a new,
situational ambient temp before applying the other factors cited?

Thanks in advance,
John Wadley, PE
Wadley Engineering
NABCEP Certified Solar PV Installer (TM)
Dallas, TX

Peter,

We cannot use load diversity to increase the number of conductors in a PV
conduit since there generally is little diversity among the conductors,
particularly on large arrays.

The more traditional conduit adjustment table to use is Table
310.15(B)(2)(a). The value from this table is multiplied by the temperature
adjustment factor in Table 

Re: [RE-wrenches] Cable Sizing - revisited, Ambient Temp

[Dave Click]

John,
240.4(B) allows the ampacity of a wire to drop below the OCPD rating so 
you could argue that wouldn't be a safety issue. It's always irritated 
me that these NEC derating factors have two decimal places so that you 
feel your calculations are extremely exact... and then your 
carefully-derated-to-126.39A wire has no problem at all on a 150A 
breaker. But that's the way it is.


It takes a lot of heating to exceed the 90C rating of a wire, but yes 
theoretically that would damage the insulation and cause a fault. As for 
voltage drop of your wires, I don't think that's as big an issue as you 
think. Heating from 40C to 80C, a wire is going to see its resistance 
increase by about 15%, so your voltage drop may go from 1.5% to 1.73%. 
Your module voltage drop is going to be the more pressing concern.


If on your drawings you state something like "conduits to be minimum 3.5 
inches above the roof" (or for residential, put the run in the attic) 
then that puts you at a 17C adder which is pretty manageable for most 
areas of the US (worst case, you're in the 61-70C temp derate range). 
And again, in some cases where you have a very hot section of conduit, 
the 10'/10% rule may let you ignore that localized heating. Since you're 
the one stamping these drawings, you have to stay within your comfort 
zone- add another 10C if you're worried about it and add some extra 
expansion joints. Or you can specify that your contractors shade all 
rooftop conduit, but I imagine that would limit your repeat business.


Dave

John Wadley wrote:

Dave,
Thanks for responding in Mr. Brooks place. Since ASHREA 2% is not the
very worst case, it seems like it might be possible for the ampacity of
the wire chosen to dip below the rating of the OCPD protecting it, if
there is not much margin. I've been trying to rationalize whether this
would become a safety issue. I don't think it would since the OCPD
protects the wire from a current source increasing beyond the expected
design output. I don't think there is much chance of that for a PV
module (unless there was a short between two strings). I think the
increased heating would more likely increase wire resistance/voltage
drop and lower production. With enough voltage drop, the inverter might
shut off.
I guess my new concern is in the most severe case where there is solar
concentration on a short section of conduit. Here, the heating effect of
both the elevated ambient temp and reduced wire resistance might lead to
premature failure of the wire insulation. If the combined heating
effects exceed the 90C rating of the wire, does the insulation embrittle
or melt? In either case, I foresee a grounding fault, and if the GFCI
failed, it could spark a fire.
I know the best solution is to keep conduit shaded and avoid these worst
case solar concentrating conditions. Sometimes. when I design a system
for a new contractor, I don't always know exactly where they plan to run
conduit on a roof (nor can I control it) and I start "what-if'ing"
whether my design numbers will be conservative enough to prevent a
system failure or a fire.

Thanks and regards,
John Wadley, PE
NABCEP Certified Solar PV Installer (TM)
Wadley Engineering

 > Date: Tue, 25 Jan 2011 15:37:20 -0500
 > From: Dave Click 
 > To: re-wrenches@lists.re-wrenches.org
 > Subject: Re: [RE-wrenches] Cable Sizing - revisited, Ambient Temp
 > Message-ID: <4d3f3480.9030...@fsec.ucf.edu>
 > Content-Type: text/plain; charset=UTF-8; format=flowed
 >
 > John,
 >
 > The 2% "ambient temperature" from ASHRAE is the appropriate starting
 > point to use for these calculations. For some additional background I'll
 > quote Bill:
 >
 > **
 > ASHRAE bases its ?warm?season temperature conditions? for each city on
 > annual percentiles of 0.4%, 1.0% and 2.0%. As an example, the June 2.0%
 > dry?bulb design temperature for Atlanta is 91.7?F. Therefore, based on a
 > 30?day month (i.e. 720 hours), the actual temperatures can be expected
 > to exceed 91.7?F a total of 14 hours a month. The corresponding 1.0%
 > design temperature (93.1?F) can be expected to be exceeded for 7 hours a
 > month; while the 0.4% design temperature (94.6?F) can be expected to be
 > exceeded for 3 hours a month (column 2).
 > **
 >
 > In Jim Dunlop's example it sounds like he's starting with the summer
 > ambient high (likely around 90F / 32C) and adding the 310.15(B)(2)(c)
 > 33C figure to reach the 61-70C range.
 >
 > IMHO, ASHRAE 2% high temperature should be the "standard practice" for
 > these conditions when calculating your base ambient temperature before
 > additional adders. There are going to be site-specific conditions like
 > your example where the conduits may heat up more than 310.15(B)(2)(c)
 > requires; in that case I think y

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

[Dave Click]

That's a nice built-in alarm feature that locking connectors just can't 
provide...


Nick Soleil wrote:

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] Parallel wire runs to increase size

[Dave Click]

310.4(B) Conductor Characteristics. The paralleled conductors in each 
phase, polarity, neutral, grounded circuit conductor, or equipment 
grounding conductor shall comply with all of the following:

(1) Be the same length
(2) Have the same conductor material
(3) Be the same size in circular mil area
(4) Have the same insulation type
(5) Be terminated in the same manner

Jason Szumlanski wrote:

Nick,

Can you cite a code section that supports this. (not challenging you –
it makes sense and I agree)

I have been wondering about SMA’s recommendation to parallel two 1/0
cables for a Sunny Island. If the wire sizes and lengths are identical,
is this acceptable?

Jason Szumlanski

Fafco Solar

*From:*re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of *Nick
Soleil
*Sent:* Wednesday, February 02, 2011 12:05 PM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] Parallel wire runs to increase size

You shouldn't parallel wiring that way. That is not acceptable by code,
and it is unnecessary. If the #10 is not sufficient just replace it. Due
to the fact that the larger wiring has much less resistance, most if not
all of the current will flow on the larger wires.

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:*"Starlight Solar, Larry Crutcher" 
*To:* RE-wrenches 
*Sent:* Wed, February 2, 2011 8:00:07 AM
*Subject:* [RE-wrenches] Parallel wire runs to increase size

Wrenches,

Some of our business involves repairing poor PV solar installations on
recreational vehicles. So often we wind up installing a roof junction
box and running a second PV to controller wire and then replacing the
controller to battery wire size. For instance, we may find a 10 gauge
wire run to the controller. We then add #8, #6, #4 or even 2 gauge and
parallel to the #10 depending on power and distance of the run. My
question: Is there a calculator or chart that will tell me what the
combination of any two wire sizes equate to? example: #10 + #4 = X

Thanks.

Larry Crutcher
Starlight Solar Power Systems 
/powered by //*S*//*TARLIGHT*/™



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Re: [RE-wrenches] Sanyo HIT and ARRA "buy american"

[Dave Click]

We had to recently deal with this. It's complicated.

As I understand it:
The WTO list of ~60 countries counts as "Buy American" ONLY IF a project 
is more than $7,804,000 (I believe this amount relates to the check 
being written for your Sanyo project, as opposed to the total funding 
amount VT received from the feds for their incentives), AND the group is 
an entity subject to US obligations under international trade 
agreements. The Appendix to Subpart B of 2 CFR (Code of Federal 
Regulations) 176 lists "U.S. States, Other Sub-Federal Entities, and 
Other Entities Subject to U.S. Obligations under International 
Agreements (as of February 16, 2010)" and at least for Florida, only 
Executive Branch Agencies may invoke international trade agreements. And 
again, only for projects valued at or above $7,804,000 for construction 
projects (2 CFR 176.90). Additional confusion comes from "Buy American" 
per the original act of 1933 and subsequent revisions being different 
from "Buy American" per ARRA.


If your project has a demonstrable need for higher-efficiency modules 
then you may be able to get a waiver from the DOE/NIST, but that's 
probably going to take a few months. So to sum up, you're facing an 
uphill battle.


Related note: I just looked at a system the other day with 
three-year-old Sanyos HIT 200s (not bifacial) with yellowing 
encapsulation- some at the busbars, but mostly in the interior of the 
modules (roughly the outer ring of cells was still clear). Anyone else 
seeing this?


Not an attorney, not legal advice, etc etc.,
Dave

Warren Lauzon wrote:

This is but one of many exceptions noted in the act "
“Recovery Act designated country” means a World Trade Organization
Government Procurement Agreement country, a Free Trade Agreement
country, or a least developed country."

https://www.acquisition.gov/far/html/Subpart%2025_6.html


-Original Message- From: Kirk Herander, VSE
Sent: Wednesday, March 09, 2011 2:56 PM
To: 'RE-wrenches'
Subject: [RE-wrenches] Sanyo HIT and ARRA "buy american"



The Sanyo literature states that sanyo wafers are made in the US. However,
DOE exemption states that the module's cells have to be produced in the US
(ie. the actual semiconductor). This would exclude Sanyo's, I presume,
under
the strict interpretation as to what a "wafer" vs. a "cell" is. The cells
are fabricated from US-made wafers in Japan, correct? You can't have the
cell without the wafer. The VT state program is balking at accepting Sanyos
for ARRA incentives because of cell vs. wafer definition.

I need to know if any of you have installed ARRA-funded system using
Sanyo's
and if this sticking point has caused problems. Any documentation you have
received from Sanyo which clarifies this issue, arguing for ARRA approval
would be most helpful. Again, this is only for ARRA-funded projects, not
other gov't stuff like DOD, etc. Thanks.

Read this article for reference:

http://solar-energy-news-and-views.blogspot.com/2011/02/how-american-are-you

r-solar-panels.html



Kirk Herander
Vermont Solar Engineering
802.863.1202
NABCEP(tm) Certified Solar Installer
NYSERDA-eligible Installer
VT Solar Incentive Program Partner

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Re: [RE-wrenches] Conductor supporting requirements

[Dave Click]

338.10(B)(4)(b) says to support in accordance with 334.30:

334.30 Securing and Supporting.
Nonmetallic-sheathed cable shall be supported and secured by staples, 
cable ties, straps, hangers, or similar fittings designed and installed 
so as not to damage the cable, at intervals not exceeding 1.4 m (4.5 ft) 
and within 300 mm (12 in.) of every outlet box, junction box, cabinet, 
or fitting. Flat cables shall not be stapled on edge.
Sections of cable protected from physical damage by raceway shall not be 
required to be secured within the raceway.


Andrew Truitt wrote:

Does anyone know the maximum support spacing for conductors in free air
and what code section addresses it?  I'm thinking of USE-2 or PV Wire
being run in loop hangars along purlins under an array.
Thanks in advance!
For a brighter energy future,

Andrew Truitt
Principal
TruittRenewableEnergyConsulting
NABCEP Certified PV Installer™ (ID# 032407-66)
(202) 486-7507 
http://www.linkedin.com/pub/andrew-truitt/8/622/713


24 copy.jpg

"Don't get me wrong: I love nuclear energy! It's just that I prefer
fusion to fission. And it just so happens that there's an enormous
fusion reactor safely banked a few million miles from us. It delivers
more than we could ever use in just about 8 minutes. And it's wireless!"

~William McDonough



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Re: [RE-wrenches] community solar

[Dave Click]

If you have a muni then it's possible, but I'd guess that with most 
investor-owned utilities they'd just laugh in your face. There are a few 
utilites out there that have done this- I think that Portland, OR and 
Seattle have this and we're working on it here in Orlando too.


These links should help:
http://votesolar.org/2010/12/community-solar-coming-to-a-town-near-you/
http://votesolar.org/communitysolar/
http://irecusa.org/wp-content/uploads/2010/11/IREC-Community-Renewables-Report-11-16-10_FINAL.pdf

Larry Brown wrote:

wrenches.

I have had several inquires into this possible scenario. anybody have
any experience doing this with their local utility?

several families in a neighborhood or community invest together to put
up a solar array either on an existing building that has excellent solar
access or a ground mount that also has a wide solar window. the system
is set up so that it is configured into sub arrays with each sub array
having an inverter and a kwh meter that records the output of that sub
array. each of the sub arrays is designated (by agreement and the proper
paper work) to a particular family based on how much they invested into
the system. the output of the whole system is then grid tied and all of
the kwh go directly to the utility. it is then just a matter of
accounting in that each of the sub arrays kwh's produced is deducted
from the kwh's used by that particular customer on their home or
business utility bill. So the customer either has a credit that is
carried over or has a balance owed that appears on the next utility bill.

The design and installation is straight forward and in one centralized
local location.
It is only a matter of paper work and accounting.
And it builds community and neighbors get to know each other
Much like Community Supported Agriculture

Larry Brown
Sun Mountain



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Re: [RE-wrenches] SLDs with Mac

[Dave Click]

Nick, you can still use Visio/AutoCAD on the Mac if you install 
Parallels or VMWare, which allow you to run Windows programs. Either of 
those would run you about $80, which is cheaper than OmniGraffle. Each 
of these three software packages have trial versions so you can check 
them out before you commit.


On 2011/4/8 7:55 PM, Nick Soleil wrote:

Hello Mac Users:
I have been using Visio Professional for my Single Line Diagrams, but am
considering a change to Mac. Can I open or edit Visio diagrams with any
Mac applications? Probably not. What programs are available for
generating electrical diagrams? Have you used OmniGraffle? It seems
really user friendly.
What about AutoCAD for Mac?
Nick Soleil
707-321-2937



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Re: [RE-wrenches] SLDs with Mac

[Dave Click]

I'm pretty happy with the new Parallels but I'm a recent Mac convert as 
well, so not too much hands-on experience. Some reviews have found that 
they can play graphics-intensive video games and do calc-intensive CAD 
work through Parallels though, so it shouldn't be a problem for Visio or 
light CAD even on slightly older hardware. Parallels looked faster than 
VMWare in the benchmarks I was able to find, but you can check for 
yourself against the VMWare trial version.


Thanks for the recommendations of DraftSight and Omnigraffle, guys! I'll 
be sure to check those out.


On 2011/4/10 3:37 PM, Keith Cronin wrote:

Max, et al.

I've also found parallels to be clunky a couple of years ago as well.
Rumored that the new version is catching up to VMWare.

Even when VMWare first came out, it was a little slow to boot the OS-
aka, Windows XP.

They've made some great strides since then, so perhaps consider an
upgrade or switch to VMWare.
Aloha,

Keith

*From:* Max Balchowsky 
*To:* RE-wrenches 
*Sent:* Sunday, April 10, 2011 8:42 AM
*Subject:* Re: [RE-wrenches] SLDs with Mac

I've got Parallels on my iMac also - yes it's too clunky to be useful.
Draftsight is working out great for Cad Dwgs on the Mac, and, again,
it's a free download...
Max Balchowsky
Design Engineer
SEE Systems
1048 Irvine Ave Suite 217
Newport Beach, Ca. 92660
760-403-6810



*From:* R Ray Walters 
*To:* RE-wrenches 
*Sent:* Sat, April 9, 2011 9:42:02 PM
*Subject:* Re: [RE-wrenches] SLDs with Mac

I've been running Parallels on a Mac for 3 years, and I just bought a PC
for the PC stuff. I like my Mac, but after waiting 1/2 an hour to boot
and update everything each time, Parallels is just really clunky.
I like Omnigraffle on my Mac. way better than simpler drawing programs,
but not near as complicated as AutoCad.
I consider it optimal for one line diagrams and simple layout stuff. Its
quick to use.

R. Walters
r...@solarray.com <mailto:r...@solarray.com>
Solar Engineer




On Apr 9, 2011, at 10:40 AM, Dave Click wrote:

 > Nick, you can still use Visio/AutoCAD on the Mac if you install
Parallels or VMWare, which allow you to run Windows programs. Either of
those would run you about $80, which is cheaper than OmniGraffle. Each
of these three software packages have trial versions so you can check
them out before you commit.
 >
 > On 2011/4/8 7:55 PM, Nick Soleil wrote:
 >> Hello Mac Users:
 >> I have been using Visio Professional for my Single Line Diagrams, but am
 >> considering a change to Mac. Can I open or edit Visio diagrams with any
 >> Mac applications? Probably not. What programs are available for
 >> generating electrical diagrams? Have you used OmniGraffle? It seems
 >> really user friendly.
 >> What about AutoCAD for Mac?
 >> Nick Soleil
 >> 707-321-2937
 >>
 >>
 >>
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[RE-wrenches] Fwd: Berkeley Lab Study Finds that Solar Photovoltaic Systems Boost the Sales Price of California Homes

[Dave Click]

All, just noticed that this email hadn't gone through to the wrench 
list. Good follow-up to our March discussion (subject line: Value of PV 
system to a home).


 Original Message 
Subject: 	Berkeley Lab Study Finds that Solar Photovoltaic Systems Boost 
the Sales Price of California Homes

Date:   Thu, 21 Apr 2011 09:36:58 -0700
From:   Ryan Wiser 
To: n...@dante.lbl.gov



Dear Colleague:

We are pleased to announce the completion of a new Berkeley Lab report: 
"An Analysis of the Effects of Residential Photovoltaic Energy Systems 
on Home Sales Prices in California."


An increasing number of homes with photovoltaic (PV) energy systems have 
sold in the U.S., yet relatively little research exists that estimates 
the impacts of those PV systems on home sales prices.A clearer 
understanding of these effects might influence the decisions of 
homeowners considering installing PV on their home or selling their home 
with PV already installed, of home buyers considering purchasing a home 
with PV already installed, and of new home builders considering 
installing PV on their production homes.


This research analyzes nearly 2000 California homes that have sold with 
PV installed.Across a large number of model specifications and 
robustness tests, the analysis finds strong evidence that California 
homes with PV systems have sold for a premium over comparable homes 
without PV systems.


Specifically, some of the key findings from the analysis include:

   *

 The average home sales price increases from PV across the full
 sample of homes in the dataset ranges from approximately $3.9 to
 $6.4 per installed watt (DC) of PV.

   *

 Most models coalesce near an average effect of $5.5/watt, which
 corresponds to a home sales price premium of approximately $17,000
 for a relatively new 3,100 watt PV system (the average size of PV
 systems in the study).

   *

 These average sales price premiums appear to be comparable to the
 investment that homeowners have made to install PV systems in
 California, and homeowners with PV also benefit from electricity
 cost savings after PV system installation and prior to home sale.

   *

 When expressed as a ratio of the sales price premium to estimated
 annual electricity cost savings associated with PV, an average
 ratio of 14:1 to 22:1 can be calculated; these results are
 consistent with those of the more-extensive existing literature on
 the impact of energy efficiency on home sales prices.

   *

 The analysis finds that sales price premiums decline as PV systems
 age.

   *

 When the data are split between new and existing homes, a large
 disparity in premiums is discovered: the research finds that new
 homes with PV in California have demonstrated average premiums of
 $2.3-2.6/watt, while the average premium for existing homes with
 PV has been more than $6/watt.

   *

 The research suggests several possible reasons for the lower
 premium for new homes, including that new home builders may also
 gain value from PV as a market differentiator, and may therefore
 have been willing to accept a lower premium in return for faster
 sales velocity.

The full report can be downloaded from:

http://eetd.lbl.gov/ea/emp/reports/lbnl-4476e.pdf

A 2-page summary of the report's key findings can be found at:

http://eetd.lbl.gov/ea/emp/reports/lbnl-4476e-rs.pdf

We appreciate the funding and support of the U.S. Department of Energy's 
Solar Energy Technologies Program, the National Renewable Energy 
Laboratory, and the Clean Energy States Alliance, and we apologize in 
advance for any cross-postings.



All the best,

Ryan Wiser, Ben Hoen, and Peter Cappers

Lawrence Berkeley National Laboratory

PS - Attached below is a press announcement that is being distributed on 
this work.



Media contact:

Allan Chen (510) 486-4210, a_c...@lbl.gov 


Technical contacts:

Ryan Wiser, (510) 486-5474, rhwi...@lbl.gov ,

Ben Hoen, (845) 758-1896, bh...@lbl.gov 

*New Berkeley Lab Study Finds that Residential Solar Photovoltaic 
Systems Boost the Sales Price of California Homes *


*Berkeley, CA--*New research by the U.S. Department of Energy's (DOE) 
Lawrence Berkeley National Laboratory finds strong evidence that homes 
with solar photovoltaic (PV) systems sell for a premium over homes 
without solar systems."We find compelling evidence that solar PV systems 
in California have boosted home sales prices," says Ben Hoen, the lead 
researcher on the study and a Principal Research Associate at Berkeley 
Lab. "These average sales price premiums appear to be comparable with 
the average investment that homeowners have made to install PV systems 
in California, and of course homeowners also benefit from energy bill 
savings after PV system installation and prior to home sale."


The research finds th

Re: [RE-wrenches] National grid hertz adjustment

[Dave Click]

Dan, I think we're only looking at an error of 20 minutes per (8760 hrs 
x 60 min / hr) = 0.00381%, well within the frequency drift allowed under 
UL 1741. So as you point out, it would only be the shorter excursions 
away from 60.0Hz that would be the issue. This shift isn't the easiest 
thing in the world to do (and then maintain)!


On 2011/6/27 15:08, Exeltech wrote:

A max of 20 minutes error per year (as stated in the article)
equates to an error of 0.228%.

Whether grid-tied inverters stay on line or not depends on
the ultimate range of the frequency excursions permitted
during the tests. UL1741 limits are 59.3 to 60.5 Hz for
fixed frequency settings. The cumulative error shown
above is well within those bounds. 59.3 Hz = -1.16%;
60.5 Hz is +0.83%.

However, I could see cases where they may allow 60.6 Hz
one day and 59.4 Hz the next. The overall net difference
would be zero for a frequency-dependent clock - but a
grid-tied inverter would spend the first day of this example
totally offline.

This would have to be a grid-wide frequency difference,
else they'd end up with some seriously large power flows
from one part of the grid to another, with potentially disastrous
results.

It will be interesting to see how they handle this.

Thanks for the post.

Dan


--- On *Sun, 6/26/11, bob ellison //* wrote:


From: bob ellison 
Subject: Re: [RE-wrenches] National grid hertz adjustment
To: "'RE-wrenches'" 
Date: Sunday, June 26, 2011, 6:40 PM

This will make it interesting to everybody with a grid tie inverter,
can we open up the specs to let them work with the “new test
variation”? The other option is that the inverters will spend a lot
more time off line.

Bob Ellison

*From:*re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of
*Roy Butler
*Sent:* Sunday, June 26, 2011 1:45 PM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] National grid hertz adjustment

I saw this as well, came over the AP news wire on Friday, June 24th.
I've been trying to figure out what they hope to gain by allowing more
frequency variation.puzzling at best!

Roy Butler

NABCEP Certified Solar PV Installer®

NYSERDA eligible PV&  wind installer

Four Winds Renewable Energy, LLC

8902 Route 46

Arkport, NY 14807

607-324-9747



www.four-winds-energy.com  



Although no trees were killed in the sending of this message,

a large number of electrons were terribly inconvenienced.






On 6/26/2011 1:31 PM, North Texas Renewable Energy Inc wrote:

This article in the local paper sounds a little like potential
trouble for grid connected inverters. I looked around on the NERC
www site without finding the report mentioned. Any other wrenches
seen anything about this experiment?

Jim Duncan

By Seth Borenstein The Associated Press

WASHINGTON -- A yearlong experiment with the nation's electric
grid could mess up traffic lights, security systems and some
computers -- and make plug-in clocks and appliances like
programmable coffee makers run up to 20 minutes fast.

"A lot of people are going to have things break, and they're not
going to know why," said Demetrios Matsakis, head of the time
service department at the U.S. Naval Observatory, one of two
official timekeeping agencies in the federal government.

Since 1930, electric clocks have kept time based on the rate of
the electrical current that powers them. If the current slips
off its usual rate, clocks run a little fast or slow.

Power companies now take steps to correct it, keeping the
frequency of the current as precise as possible.

The North American Electric Reliability Corp., which oversees
the U.S. power grid, is proposing an experiment that would allow
more frequency variation without corrections, according to a
June 14 company presentation obtained by The Associated Press.

The test is tentatively set to start in mid-July.

Tweaking the power grid's frequency is expensive and takes a lot
of effort, said Joe McClelland, head of electric reliability for
the Federal Energy Regulatory Commission.

"Is anyone using the grid to keep track of time?" McClelland
said. "Let's see if anyone complains if we eliminate it."

No one is quite sure what will be affected. This won't change
the clocks in cellphones, GPS or even on computers.

But wall clocks and those on ovens and coffee makers -- anything
that flashes "12:00" when it loses power -- may be a bit off
every second, and that error can grow with time.

VCRs or DVRs that get their time from cable systems or the
Internet probably won't be affected, but those with clocks tied
 

Re: [RE-wrenches] Fed ITC

[Dave Click]

Yes. It looks like some efficiency improvements only qualify on a main 
home, but it's different for solar.


http://www.irs.gov/pub/irs-pdf/f5695.pdf
Page 4: Qualified solar electric property costs. Qualified solar 
electric property costs are costs for property that uses solar energy to 
generate electricity for use in your home located in the United States. 
This includes costs relating to a solar panel or other property 
installed as a roof or a portion of a roof. The home does not have to be 
your main home.


On 2011/7/9 9:24, Dave Palumbo wrote:

Can individuals take a Fed ITC on a SHW system installed on a second
home property?

David Palumbo

Independent Power LLC

462 Solar Way Drive

Hyde Park, VT 05655**

*/www.independentpowerllc.com /*

NABCEP Certified PV Installer

Vermont Solar Partner

23 Years Experience, (802) 888-7194



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Re: [RE-wrenches] Grounding system for a shack on a frozen lake?

[Dave Click]

Per 690.41 you probably wouldn't need to ground it for a system like 
this, but I like the idea of dropping a ground rod down into the water. 
Then curve the end and find a big worm, of course.


**
690.41 System Grounding. For a photovoltaic power source, one conductor 
of a 2-wire system with a photovoltaic system voltage over 50 volts and 
the reference (center tap) conductor of a bipolar system shall be 
solidly grounded or shall use other methods that accomplish equivalent 
system protection in accordance with 250.4(A) and that utilize equipment 
listed and identified for the use.

**

On 2011/8/9 8:34, Drake wrote:

That is an amusing concept, and it sounds like a fun project. Why not
poke a hole in the ice and drop the rod in the water? If the water is
not too deep, send it to the bottom. It certainly will be below the
permanent moisture level!


At 01:34 AM 8/9/2011, you wrote:

Sounds like a silly question but is there any way to ground a small
battery based PV system serving a temporary fishing shack on the
middle of a frozen lake? Around here they call these 8' x 8' (or
larger) shacks "ice houses". One or more holes are augered through the
ice for fishing lines. Some of the shacks get remarkably fancy, almost
luxurious (in a guy kind of way). There is usually plenty of beer and
snacks. Sometimes fish, too. The shacks get set in place as soon as
the ice is solid (4-6" thick) and they may stay there for several
months. It's a home away from home for a lot of upper midwest folks in
the winter. Some like the idea of a small solar powered battery system
for light, CD player, TV, etc. There's no earth around for hundreds of
yards, even miles.

Charlie Pickard
Aladdin Solar
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Drake Chamberlin
ATHENS ELECTRIC
OH License 44810
CO license 3773
NABCEP Certified PV


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Re: [RE-wrenches] mechanical vs. electronic kwh meter

[Dave Click]

I just asked a guy I know in utility metering, and he confirms that 
there's no basis for the utility's concern. Their claim that backfeeding 
is a safety hazard could be an attempt to dissuade some non-PV folks 
from flipping their meters to steal power. Or that could be their 
justification to charge the customer for the new electronic meter (some 
utilities do this, apparently).


As an anti-theft precaution, some mechanical meters don't actually spin 
backwards- so whether you're importing or exporting a 1kW, after an hour 
your counter has ticked up by one. So just because it's a mechanical 
meter doesn't mean that you should necessary leave it running until the 
utility installs that bidirectional electronic meter.


On 2011/8/12 9:45, Kirk Herander wrote:

Hello,

I am now in a debate with the metering dept. of a local utility. They
don’t want a PV system to be energized and tested until a bidirectional
electronic meter is installed. They insist that an old plain Jane
mechanical meter can be damaged and is a safety concern if power is
pushed through it (its running backwards) to the grid. I have never
heard of, witnessed, or been told this by any utility or AHJ inspector
until now. Have any of you ever?

I don’t know the reason for their paranoia. I assume that many utility
districts don’t to this day install bidirectional electronic meters. And
rely on the original mechanical meter to count backwards reliably and
safely.

Kirk Herander

VT Solar, LLC

dba Vermont Solar Engineering

NABCEP^TM Certified installer Charter Member

NYSERDA-eligible Installer

VT RE Incentive Program Partner



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Re: [RE-wrenches] 310.15(A)(2) Exception

[Dave Click]

As I read the rule, that 100' in the trench allows you to go 10' above 
grade on each side while just worrying about the ampacity in the 100' 
section (be sure to check that your terminals are OK). For 200' in the 
trench, you're still looking at 10' above grade on each side. The rule 
doesn't say that you can only use this exception once per circuit, so 
it's fine that you use it once at each end.



On 2011/8/17 12:22, Brian Mehalic wrote:

Question about the 10'/10% rule - the exception states "adjacent
portions of a circuit."  How does this apply to an underground conduit
run, where there are two ends exposed to higher ambient temperatures
than the length in the ground?

For example, what if there is 100 feet in the trench, and 7 feet above
grade on either side? Can the exception be applied? How about 200 feet
in the trench and 7 feet above grade on either end?

Thanks,
Brian

--

Brian Mehalic
NABCEP Certified Solar PV Installer™ R031508-59
IREC ISPQ Certified Affiliated Instructor/PV US-0132
PV Curriculum Developer and Instructor
Solar Energy International
Carbondale, CO 81623
http://www.solarenergy.org



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Re: [RE-wrenches] 310.15(A)(2) Exception

[Dave Click]

That's right, Drake. The long wire acts as a heat sink for that short 
section.



On 2011/8/17 17:58, Drake wrote:

I think this answers a question I was pondering. If a conduit is run on
standoffs over a roof, the temperature is cooler than on the roof, so
the derating of the wire's ampacity is less. It would appear from
310.15(A)(2) Exception that it would _not_ be necessary to limit the
ampacity of the wire to that of the hottest temperature zone, which is
zero distance above the roof where the conductors penetrate.

Is this a correct interpretation?

Thanks,

Drake

At 01:51 PM 8/17/2011, you wrote:

As I read the rule, that 100' in the trench allows you to go 10' above
grade on each side while just worrying about the ampacity in the 100'
section (be sure to check that your terminals are OK). For 200' in the
trench, you're still looking at 10' above grade on each side. The rule
doesn't say that you can only use this exception once per circuit, so
it's fine that you use it once at each end.


On 2011/8/17 12:22, Brian Mehalic wrote:

Question about the 10'/10% rule - the exception states "adjacent
portions of a circuit." How does this apply to an underground conduit
run, where there are two ends exposed to higher ambient temperatures
than the length in the ground?

For example, what if there is 100 feet in the trench, and 7 feet above
grade on either side? Can the exception be applied? How about 200 feet
in the trench and 7 feet above grade on either end?

Thanks,
Brian

--

Brian Mehalic
NABCEP Certified Solar PV Installer™ R031508-59
IREC ISPQ Certified Affiliated Instructor/PV US-0132
PV Curriculum Developer and Instructor
Solar Energy International
Carbondale, CO 81623
http://www.solarenergy.org 



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Drake Chamberlin
ATHENS ELECTRIC
OH License 44810
CO license 3773
NABCEP Certified PV


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Re: [RE-wrenches] Enphase 215

[Dave Click]

The inverter should be current-limited on its output. The other Enphases 
have a higher output power than rated (199 @ 190, 219 @ 210, if memory 
serves from earlier list posts), so this may have a similar window.


215Wac max inverter output / 240V = 0.896
0.896 x 17 = 15.23A
15.23A x 1.25 < 20A so it's OK.
As long as the inverter output is actually 225W or less, you can fit 17 
on a 20A circuit.


As before, you'd have the inverter limiting output when the high-power 
modules are actually performing near or above STC. There will certainly 
be times during the year where the inverters are maxed out but those 
times will be a small portion. Enphase had some documentation on their 
site about this where they claimed it wasn't worth worrying about, but 
it's a site-specific question that the installer should answer.


On 2011/8/24 0:20, Keith Cronin wrote:

Hey gang

With the 215's on the scene and the tech literature on their website,
they state you can put up to 17 modules on a string.

Locally, I see folks throwing on 17-235 watt modules. Back of the
napkin- 235 watts/240 volts = .97 amps.

17 x .97 = 16.49 amps on the 20 amp circuit. Pushing the envelop of the
circuit, per NEC and in situations of lower voltage, could tip the
current higher, per module it seems or is the unit current limiting?

Wouldn't it seem plausible to ebb on 16 vs the 17? The 15 amp circuit to
20 amp circuit also is a change for the industry at large, as well as a
few other changes.

As Solarworld is rolling out their 250 watt and others in the same zone,
it seems there should/could be some caveats on the enphase literature to
reflect this.
Thoughts, comments?

Keith


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Re: [RE-wrenches] Ladders for Inspectors

[Dave Click]

A letter from your insurance company may do the trick here. They 
probably wouldn't be too happy about the homeowner, curious child, OR 
inspector using your ladder even if you are on site watching it.


On 2011/9/1 7:45, Jason Szumlanski wrote:

Is anyone being forced to leave ladders up and secured in place for
inspectors? One jurisdiction in our neck of the woods is insisting that
we do this. I believe this is a serious risk to public safety, and I
won’t be responsible for some homeowner or curious child getting injured
on or around a ladder propped against a building. The jurisdiction does
not do timed inspections, so we can’t even be there to raise the ladder
for them.

Can anyone point to some resources (OSHA?) that I can use to convince
the building official that this is a very bad idea?

Jason Szumlanski

Fafco Solar



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Re: [RE-wrenches] Designing PV systems for lightning prone areas

[Dave Click]

To add to Ray's comments, it's a good idea to minimize the area of your 
source circuits' wiring loops as well, to minimize voltage jumps from 
nearby strikes (of course, direct strikes blast a hole in the roof, so 
no suppression can really help you there). I have a DC arrestor from 
surgesuppression.com (made here in Florida) on my house's array. Nothing 
on the AC side yet but I'm planning to add it eventually.


I second Ray's recommendation that you work with a lighting protection 
specialist.


On 2011/9/9 16:00, Ray Walters wrote:

Low impedance grounding is the most important. We have a ground
impedance tester, and anything less is just guess work.
Uffer grounds (tied to exposed rebar in the footing) are usually lower
impedance than rods, also a steel cased well can be an excellent ground,
since it is essentially a metal conductor going down to the water table.
You might also consider lightning diffusers on high points along the
peak of the roof a couple of feet higher than the array.
Consider working with a lightning protection specialist.
For arrestors/ suppressors stay away from the Deltas (not very effective
from my experience) but take a look at Midnite Solar's new line of
lightning protection equipment.

Ray Walters
Solarray, Inc.

On 9/9/2011 12:32 PM, James Rudolph wrote:


Dear Wrenches,

Does anybody have any best practices for designing large PV arrays on
metal building in lightning prone areas? Lightning arrestors on the DC
side and Surge suppressors on the AC load side? Any input or resources
would be greatly appreciated.

Sunny Regards,

James Rudolph
NABCEP Certified Installer
Master Electrician
SF Energy



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Re: [RE-wrenches] Module Load Rating

[Dave Click]

UL 1703 is a 30 psf positive (downward) or negative (upward) load, or a 
design load designated by the manufacturer. I've never seen a module 
advertising a 30psf loading requirement--everything I've seen is at 
least 50psf--which I take to mean that this "designated" design load is 
usually spec'd by manufacturers to be 50 psf. 30 psf is pretty weak.


The UL tests themselves then actually go to 1.5 times that design load 
as a safety factor. The load tests last 30 minutes. As I understand it 
(based off a coworker's conversation with a Schott rep), this is why 
Schott advertises that their modules withstand 75psf front and back. The 
rep questioned why all manufacturers weren't advertising 75psf.


IEC 61215 also tests both upwards and downwards loading. Since it's 
written by some French people, they specify a 2400 Pascal load, which is 
50.1 psf, for both the front and back of the module. They do this in 
three cycles of tests (50psf front, 50 psf back being one cycle). 
However, "if the module is to be qualified to withstand heavy 
accumulations of snow and ice," then during the third cycle they go to 
5400 Pa for the FRONT loading. 5400 Pa is 112.8 psf. Each load test 
lasts 1 hour. If a module manufacturer claims 113psf uplift resistance 
then either they misunderstand the IEC standard or they make the Hulk of 
PV (without the smash). Note that the IEC standard does not have the 1.5 
safety factor.


Some test labs offer a package deal where they test modules to UL and 
IEC requirements at the same time to qualify a module for worldwide 
sale-- so they go through each test and pick the harder requirements 
(between UL and IEC) so that passing each test means the module is 
certified to meet both standards. IEC's 50 psf loading may have caused 
some manufacturers to designate the 50 psf load for UL. Or, module 
manufacturers just do the 50psf IEC load which corresponds to a 
"designated" 33.3 psf load for UL times that 1.5 factor.




On 2011/10/6 17:03, Jamie Johnson wrote:

Rich, It is my understanding that modules are tested to 113psf downforce
or snow load and 52psf uplift for their NRTL listing (uplift is also a
load rating denoted as negative pressure) (don't have a copy of the
testing procedures in front of me however I have confirmed this with
more than one module manufacturer in the past).
It seems to make sense as many framed single glass modules appear to
have a wider lip under the glass and a narrow lip above the glass, there
may also be other reasons.
There are a few manufacturers out there that have had additional testing
done and will certify their modules to 75psf or 113psf uplift, usually
they have 2 layers of glass and/or a thicker AL frame and are also
heavier like the Schott 300 watt module.
Since all of our installs are in a High Velocity Windzone Area, when we
have a module manufacturer with single glass normal AL frame modules
that claim 113psf loads (uplift) we will always challenge them on it and
see if they will actually stand by that claim, in every single case
after researching it, they have backed away from the claim and
acknowledged that their modules will only withstand 52 or 53psf uplift.
It is important to understand that the load rating listed on the
marketing material (downforce or snow load) is usually not the same as
the uplift or negative pressure rating.
In our area of FL for a 130MPH windzone, our uplift or negative
pressures on a module can range from -32 to -49PSF although our
downforce is usually lower around +16. In a 140MPH windzone you can
easily exceed a normal module uplift rating of -52PSF, and although
adding a 3rd rail may reduce frame stress, it will do little to keep the
glass from blowing out in a hurricane.
As to the honesty question, IMHO the guilty parties are most likely the
marketing dept staff who lack technical expertise.
Hope this helps.

*Jamie Johnson
NABCEP Certified PV Technical Sales Professional
NABCEP Certified Solar PV Installer

General Manager*
*SOLAR POWER ELECTRIC*
**
**

 Original Message 
Subject: [RE-wrenches] Module Load Rating
From: "Rich Nicol" mailto:r...@solartechvt.com>>
Date: Thu, October 06, 2011 1:41 pm
To: mailto:g...@icarussolarservices.com>>, "'RE-wrenches'"
mailto:re-wrenches@lists.re-wrenches.org>>

Hi Wrenches –
I’ve noticed discrepancies in load rating methods for various
modules and wondered if there was any insight from the installer
community. REC claims 113 PSF, Sharp claims only 50PSF. Solarworld
notes 50PSF load rating, but 113 PSF snow load rating. I’m assuming
the difference is that snow load rating is greater because its
assumed to be widely distributed, but yet its still per square foot
so perhaps not. Is a Sharp module such as the 240NUQ-240F2 as
durable as REC, Evergreen, Solarworld etc and they are just more
honest in their portrayal of load rating.
Thanks for your help,
Rich
**

Re: [RE-wrenches] Module Load Rating

[Dave Click]

Hi Jamie-

Yes, it would certainly make sense for manufacturers to put forward the 
wind pressures in a consistent manner. Maybe the next SolarPro module 
roundup could include some of this info if someone has 100 hours to 
spend contacting someone knowledgeable at each module manufacturer...


I agree that if Schott specs a UL test for 50 psf (ie a test of 75psf) 
they should call it that. Claiming 75psf under UL 1703 should therefore 
include testing at 112.5psf.


On 2011/10/7 10:26, Jamie Johnson wrote:

Dave, thanks for the clarification on the difference between NRTL and
IEC tests.
Wouldn't it make sense for the manufacturers to put the negative and
positive test and certified (warranted) pressures on the data sheets or
in the installation manual so there is no confusion for the installation
community?
In other words, they could state if they used a safety factor in the
test for determining maximum module loads both uplift and downforce.
Also please clarify. If Schott specifies a UL test for a 50psf working
load and with the 1.5x safety factor the module is tested to 75psf, then
in my mind that module is only rated for 50psf for installation
purposes, the safety factor is not counted.
If Schott wants to state a working load of 75psf then their modules
should be UL tested to 112.5psf? Or am I missing something here?
**
*Jamie Johnson
NABCEP Certified PV Technical Sales Professional
NABCEP Certified Solar PV Installer

General Manager*
*SOLAR POWER ELECTRIC*
**
**

 Original Message 
Subject: Re: [RE-wrenches] Module Load Rating
From: Dave Click mailto:davecl...@fsec.ucf.edu>>
Date: Fri, October 07, 2011 9:31 am
To: RE-wrenches mailto:re-wrenches@lists.re-wrenches.org>>

UL 1703 is a 30 psf positive (downward) or negative (upward) load, or a
design load designated by the manufacturer. I've never seen a module
advertising a 30psf loading requirement--everything I've seen is at
least 50psf--which I take to mean that this "designated" design load is
usually spec'd by manufacturers to be 50 psf. 30 psf is pretty weak.

The UL tests themselves then actually go to 1.5 times that design load
as a safety factor. The load tests last 30 minutes. As I understand it
(based off a coworker's conversation with a Schott rep), this is why
Schott advertises that their modules withstand 75psf front and back.
The
rep questioned why all manufacturers weren't advertising 75psf.

IEC 61215 also tests both upwards and downwards loading. Since it's
written by some French people, they specify a 2400 Pascal load,
which is
50.1 psf, for both the front and back of the module. They do this in
three cycles of tests (50psf front, 50 psf back being one cycle).
However, "if the module is to be qualified to withstand heavy
accumulations of snow and ice," then during the third cycle they go to
5400 Pa for the FRONT loading. 5400 Pa is 112.8 psf. Each load test
lasts 1 hour. If a module manufacturer claims 113psf uplift resistance
then either they misunderstand the IEC standard or they make the
Hulk of
PV (without the smash). Note that the IEC standard does not have the
1.5
safety factor.

Some test labs offer a package deal where they test modules to UL and
IEC requirements at the same time to qualify a module for worldwide
sale-- so they go through each test and pick the harder requirements
(between UL and IEC) so that passing each test means the module is
certified to meet both standards. IEC's 50 psf loading may have caused
some manufacturers to designate the 50 psf load for UL. Or, module
manufacturers just do the 50psf IEC load which corresponds to a
"designated" 33.3 psf load for UL times that 1.5 factor.



On 2011/10/6 17:03, Jamie Johnson wrote:
>  Rich, It is my understanding that modules are tested to 113psf
downforce
>  or snow load and 52psf uplift for their NRTL listing (uplift is also a
>  load rating denoted as negative pressure) (don't have a copy of the
>  testing procedures in front of me however I have confirmed this with
>  more than one module manufacturer in the past).
>  It seems to make sense as many framed single glass modules appear to
>  have a wider lip under the glass and a narrow lip above the glass,
there
>  may also be other reasons.
>  There are a few manufacturers out there that have had additional
testing
>  done and will certify their modules to 75psf or 113psf uplift, usually
>  they have 2 layers of glass and/or a thicker AL frame and are also
>  heavier like the Schott 300 watt module.
>  Since all of our installs are in a High Velocity Windzone Area,
when we
>  have a module manufacturer with single glass normal AL frame modu

Re: [RE-wrenches] GT inverter

[Dave Click]

The Square D switches would work (as would others, I'm sure, but I knew 
how to find this file). And you don't need to break each pole twice:

http://static.schneider-electric.us/docs/Electrical%20Distribution/Safety%20Switches/Solar%20Disconnect%20Switches/3110DB0401.pdf

Note wiring diagrams 1A, 1C, and 1E.

On 2011/11/21 9:49, mac Lewis wrote:

Jay,

I'm not sure as far as external disconnects.  In the handful that we
have installed, we have been able to use the integrated disconnects.
  Could you use a standard DC double-pole double-throw and run the + and
- through each pole?



On Sun, Nov 20, 2011 at 3:36 PM, jay peltz mailto:j...@asis.com>> wrote:

HI mac,

I like this choice also.

But what is on the market for a TL fused disco?

jay
On Nov 20, 2011, at 1:59 PM, mac Lewis wrote:


I would see if the Aurora 6000 would be a good fit.  I believe it
will string but it may clip depending on tilt, orientation and
anticipated temps.


Mac

On Sun, Nov 20, 2011 at 2:44 PM, jay peltz mailto:j...@asis.com>> wrote:

Hi All,

Anybody have  a favorite string GT inverter for the following.

6700 watts
30 x sanyo 225 watt

no shading
240v output

thanks,

jay

peltz power





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Re: [RE-wrenches] calculating low string voltage

[Dave Click]

At an SMA training last year they recommended the following temperature 
adders:


Open field: +22°C
Rooftop, lots of ventilation: +28°C
Rooftop, some ventilation: +29°C
Rooftop, little ventilation: +32°C
Rooftop BIPV, no ventilation: +43°C
Façade, some ventilation: +35°C
Façade, little ventilation: +39°C
Façade BIPV, no ventilation: +55°C

For your Sanyo project, I'd agree that the pole mount would be a good 
fit and +25C would seem to be OK. As you know, the 301VDC VMP on an 
inverter with a 300V+ tracking window wouldn't work very well during the 
summers for very long. My own rooftop system has a design VMP of around 
294 at 70C module temperature and I've seen it a bit lower than that on 
a sunny day-- I think it's because in irradiances below 1000Wm/2, the 
modules can still get plenty hot but the lower irradiance doesn't bring 
the VMP up to 100%. So all told, maybe plan for an array minimum of:


Inverter Tracking Minimum
/0.85 (degradation and voltage tolerance)
/0.95 (effect I just described)
/0.825 (60C operating temp)
= minimum string VMP at STC

(similar to what Bill said)

On 2011/11/30 11:04, Kirk Herander wrote:

Thanks for all the good response. Speaking of monkey wrenches, these are
Sanyo HIT Double panels, mounted on a rack which is 5 ½ feet  above the
roof surface. They will absorb reflected light on the backside, so I
assume the cells will operate at a higher temp. But they are elevated
enough to simulate a pole-mount, thus lowering operating cell temp. So
what operating temp to use? If I use 25 C as the operating temp, the low
voltage calc comes out to 301 vdc (inverter min is 300 – using SMA
US8000). If I use 15 C the calc is 308 vdc. This is for a 6 panel
string. Unfortunately I really don’t want to use 7 panel strings due to
the layout. If I used a US7000 it would work since min vdc in is 250.
However the inverters are part of a SunnyTower and I can’t swap a 7000
for an 8000 without voiding the Tower UL listing.

Kirk Herander

VT Solar, LLC

dba Vermont Solar Engineering

NABCEP^TM Certified installer Charter Member

NYSERDA-eligible Installer

VT RE Incentive Program Partner

*From:*re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of
*b...@midnitesolar.com
*Sent:* Wednesday, November 30, 2011 1:03 AM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] calculating low string voltage



If you really want to throw a monkey wrench into the mix, bring up
partial shading...

Or, maybe that's just not allowed in that debate ?? Just a thought.

boB







On 11/29/2011 8:39 PM, Kent Osterberg wrote:

Kirk,

You've got some good feedback on this from Ray and Bill. I'll try to add
a little more. Most module datasheets show a normal operating cell
temperature, NOCT, value that's typically 47.5°C. That's 20°C ambient
temperature, 800 W/sq m, and calm wind and nothing blocking the airflow
on the back of the module. That 27.5°C temperature rise should be pretty
close to the temperature rise that occurs for a pole-top mount. It's
common to see people use 25°C for modules on a pole and 30°C or 35°C on
a roof and there are data that support these "typical" values. With 1000
W/sq irradiance, the temperature rise can obviously be more too. Between
the intensity of the sun, the direction of the sun, the color of the
roof, the spacing off the roof, and the wind speed there is a lot that
is different from one system to the next or even one day to the next.

Most PV module spec sheets don't give you a temperature coefficient for
Vmp. I've seen people use the the Voc coefficient, usually expressed as
a percentage, for both Voc and Vmp. Big mistake. Data from NREL
indicates as Bill said, the temperature coefficient for Vmp is higher
than that the temperature coefficient for Voc. That's particularly true
when the coefficient is expressed as a percentage per °C. Since there
are very few manufacturer's that give both temperature coefficients,
I'll use a value from an old Evergreen module for an example. The
Evergreen ES-195 datasheet shows Voc = 30.5 volts with a coefficient of
-0.34%/°C and Vmp = 27.1 volts with a coefficient of -0.47%/°C. Since
one shouldn't add volts and percents, I'll put the temperature
coefficients in volts/°C: Voc = 30.5 V - 0.10 V/°C and Vmp = 27.1 V -
0.13V/°C. So Vmp is moving faster than Voc, but not a lot faster. That's
generically true for c-Si or poly-Si.

Kent Osterberg

Blue Mountain Solar, Inc.

www.bluemountainsolar.com  

t: 541-568-4882


On 11/29/2011 11:48 AM, Kirk Herander wrote:

I am in debate with a PE over calculation of low voltage of a series
string on a hot day. He insists that an arbitrary high cell temp is
factored in, not just ambient temperature. Could someone please give an
accepted formula for this calculation? Thanks. I cannot find a clear
reference to low voltage calculation on a hot day (but every reference
material is clear on how to calculate high voltage on a cold d

Re: [RE-wrenches] calculating low string voltage

[Dave Click]

Ray, I'd use the 2% high temp. The 0.4% high temp would only be reached 
a few hours out of the year. However, the 0.4% high is only a few degC 
warmer than the 2% high, so that would change my fudge factor below by a 
max of 1.8-2.0%.


On 2011/12/1 15:48, Ray Walters wrote:

That's more detailed info, but I still am wondering what ambient temp to
apply (which AHSRAE #) with the temp adder. Daryl suggested using a 2%
high temp. Also, where are you all getting your weather data? I found
the NEC suggested ASHRAE manual to be close to $200. That's a bit much
just to get a couple of numbers for our design.
It seems this calculation of low voltage is far from being entirely
codified, and I'm trying to standardize it somewhat for my PV class. Non
of the design manuals I have currently are even close to this level of
complexity, yet this is obviously an important calculation. Should I
suggest that my students just use the inverter manufacturers' online
tools, and forget about trying to run this voltage calc themselves?

Thanks,

Ray

On 12/1/2011 6:30 AM, Dave Click wrote:

At an SMA training last year they recommended the following
temperature adders:

Open field: +22°C
Rooftop, lots of ventilation: +28°C
Rooftop, some ventilation: +29°C
Rooftop, little ventilation: +32°C
Rooftop BIPV, no ventilation: +43°C
Façade, some ventilation: +35°C
Façade, little ventilation: +39°C
Façade BIPV, no ventilation: +55°C

For your Sanyo project, I'd agree that the pole mount would be a good
fit and +25C would seem to be OK. As you know, the 301VDC VMP on an
inverter with a 300V+ tracking window wouldn't work very well during
the summers for very long. My own rooftop system has a design VMP of
around 294 at 70C module temperature and I've seen it a bit lower than
that on a sunny day-- I think it's because in irradiances below
1000Wm/2, the modules can still get plenty hot but the lower
irradiance doesn't bring the VMP up to 100%. So all told, maybe plan
for an array minimum of:

Inverter Tracking Minimum
/0.85 (degradation and voltage tolerance)
/0.95 (effect I just described)
/0.825 (60C operating temp)
= minimum string VMP at STC

(similar to what Bill said)

On 2011/11/30 11:04, Kirk Herander wrote:

Thanks for all the good response. Speaking of monkey wrenches, these are
Sanyo HIT Double panels, mounted on a rack which is 5 ½ feet above the
roof surface. They will absorb reflected light on the backside, so I
assume the cells will operate at a higher temp. But they are elevated
enough to simulate a pole-mount, thus lowering operating cell temp. So
what operating temp to use? If I use 25 C as the operating temp, the low
voltage calc comes out to 301 vdc (inverter min is 300 – using SMA
US8000). If I use 15 C the calc is 308 vdc. This is for a 6 panel
string. Unfortunately I really don’t want to use 7 panel strings due to
the layout. If I used a US7000 it would work since min vdc in is 250.
However the inverters are part of a SunnyTower and I can’t swap a 7000
for an 8000 without voiding the Tower UL listing.

Kirk Herander

VT Solar, LLC

dba Vermont Solar Engineering

NABCEP^TM Certified installer Charter Member

NYSERDA-eligible Installer

VT RE Incentive Program Partner

*From:*re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of
*b...@midnitesolar.com
*Sent:* Wednesday, November 30, 2011 1:03 AM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] calculating low string voltage



If you really want to throw a monkey wrench into the mix, bring up
partial shading...

Or, maybe that's just not allowed in that debate ?? Just a thought.

boB







On 11/29/2011 8:39 PM, Kent Osterberg wrote:

Kirk,

You've got some good feedback on this from Ray and Bill. I'll try to add
a little more. Most module datasheets show a normal operating cell
temperature, NOCT, value that's typically 47.5°C. That's 20°C ambient
temperature, 800 W/sq m, and calm wind and nothing blocking the airflow
on the back of the module. That 27.5°C temperature rise should be pretty
close to the temperature rise that occurs for a pole-top mount. It's
common to see people use 25°C for modules on a pole and 30°C or 35°C on
a roof and there are data that support these "typical" values. With 1000
W/sq irradiance, the temperature rise can obviously be more too. Between
the intensity of the sun, the direction of the sun, the color of the
roof, the spacing off the roof, and the wind speed there is a lot that
is different from one system to the next or even one day to the next.

Most PV module spec sheets don't give you a temperature coefficient for
Vmp. I've seen people use the the Voc coefficient, usually expressed as
a percentage, for both Voc and Vmp. Big mistake. Data from NREL
indicates as Bill said, the temperature coefficient for Vmp is higher
than that the temperature coefficient for Voc. That's particular

Re: [RE-wrenches] SMA combi switch in s.s.

[Dave Click]

Marco, the easiest solution may be to just replace it with a 4-pole 
disconnecting combiner from another manufacturer. SolarBOS, for example, 
has one available in 4X (fiberglass or SS).


On 2011/12/7 12:41, Marco Mangelsdorf wrote:

Anyone ever come across the SMA combi switch in a stainless enclosure?

I’ve got one of the standard combis rotting away like crazy as it’s
right next to the ocean.

Thanks,

marco



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Re: [RE-wrenches] lay in lugs

[Dave Click]

Burndy's changed its part# from the CL50-DB-T to the CL50-1TN. Still 
direct-burial, still tin-plated, still "commonly used for solar panel 
grounding." The tech support guy I spoke with last December said that 
their lugs are now all direct-burial, so they decided that there wasn't 
a point in keeping up the DB designation.


DKC

 Original Message 
Subject: Re: [RE-wrenches] lay in lugs
From: August Goers 
To: RE-wrenches 
Date: 2009/04/30 21:00


Todd -

Burndy and Ilsco both make similar tin coated copper lay in lugs.
Here are two manufacturer part numbers:

Ilsco GBL4 DBT

Burndy CL50-DB-T

Other wrenches, let me know if these parts numbers don't sound right.


As has been mentioned on this list several times, Wiley makes really
nice lugs for grounding your rails:

http://www.we-llc.com/WEEB.html

Both the Burnday and Illsco lugs are similar as far as I can tell and
include a stainless set screw. Prices vary, so be careful. You then
need to decide how to you want to fasten them to the module frame.
Many folks use SS 10-32 thread forming screws but I found that the
crew members were commonly stripping the soft aluminum module frames
during installation. I can't keep those guys away from their impact
drivers! Now we use a SS 10-32 thread forming screw and a SS kep nut
on the backside of the frame. The thread forming screw cuts right
though the manufacturer supplied ground spot and them the kep nut
assures that we can go good and tight. We always use a SS star washer
between the lug and the frame. And the kep nut includes a star washer
built in which keeps the install fast. Sample nut pic:

http://www.allproducts.com/manufacture7/femico/kkep.html

These lugs are widely available from most solar suppliers.

Yea, those old standard aluminum lay in lugs just don't hold up in
our climate, at least.

Best, August




August Goers


Luminalt Energy Corporation 4000 Irving Street San Francisco, CA
94122


Office:  415.564.7652 Mobile:  415.559.1525 aug...@luminalt.com 
www.luminalt.com






 From: Todd Cory
 To: RE-wrenches
 Sent: Thursday, April 30, 2009
4:11:27 PM Subject: [RE-wrenches] lay in lugs

Does anyone have a part number for the lay in lugs they use for
module grounding? I don't want copper or aluminum ones because of
problems with dissimilar metals. Don't they make a tin plated copper
one that works with the aluminum module frames? My wholesaler cannot
seem to find the part number.

Thanks,

Todd ___ List sponsored
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Re: [RE-wrenches] plug in gridtied inverter

[Dave Click]

I'm not sure what my favorite part is:
1. the note at the bottom of the page of "NOTE: This unit is NOT UL 
listed so it can only be represented as an experimental device. It does 
shut down and disconnect from the grid if it senses that the grid has 
gone down (power outage). This protects utility workers from 
electrocution while working on power lines. You must assume all 
liability when using this device. "


2. the picture on the box of the 10kW+ PV system and 1MW wind turbines 
which can be connected to "Multiple-Units paralleled for greater power 
input to the 'Grid'"


I'm torn as to spending $300 on either two of these units or the 
website's "hydrogen generator" which apparently fits easily underneath 
the hood of my Accord.


DKC

 Original Message 
Subject: [RE-wrenches] plug in gridtied inverter
From: jay peltz 
To: RE-wrenches 
Date: 2009/05/06 11:53


What you think of this!

http://www.wildnaturesolutions.com/200winverter.html

Yikes,
jay

peltz power
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Re: [RE-wrenches] residential ITC and second homes

[Dave Click]

From DSIRE:
http://www.dsireusa.org/incentives/incentive.cfm?Incentive_Code=US37F&re=1&ee=1
"The home served by the system does not have to be the taxpayer’s
principal residence."

And from the IRS:
http://www.irs.gov/pub/irs-pdf/f5695.pdf
"Your main home is generally the home where you live most of the time. A
temporary absence due to special circumstances, such as illness,
education, business, military service, or vacation, will not change your
main home."

"Qualified solar electric property costs are costs for property that
uses solar energy to generate electricity for use in your home located
in the United States. This includes costs relating to a solar panel or
other property installed as a roof or a portion of a roof.The home does
not have to be your main home."

DKC

 Original Message 
Subject: [RE-wrenches] residential ITC and second homes
From: Kirk Herander, VSE 
To: 'RE-wrenches' 
Date: 2009/6/1 11:57


I recently had a customer tell me their vacation home is not eligible
 for the tax credit. I cannot find any reference excluding part-time
 residences from the ITC, and have had several customers take the
credit in this situation. Does anyone know of a link where the rules
pertaining to part-time residences are spelled out clearly? Thanks.



Kirk Herander

Vermont Solar Engineering

802.863.1202

NABCEP(tm) Certified Solar Installer

NYSERDA-eligible Installer

VT Solar Incentive Program Partner







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Re: [RE-wrenches] What is a "direct-current system"?

[Dave Click]

Peter, (back to the Wrenches list)

Yep, 690.47(C) would apply to conventional grid-tied no-battery systems. 
Sorry for the litany of code references:


690.47(C)(7) does refer to 250.166. As I understand it, you need to size 
your GEC from your Xantrex ground bar (690.47(C)(5)) per 250.66 and 
250.166 (pick whichever requires the larger conductor), as required in 
690.47(C)(7). Note that when you're running your AC EGC in the Xantrex 
units, the installation guide (last I checked) required you to actually 
run that EGC from the ground bar rather than what looks to be the AC EGC 
terminal.


DKC


 Original Message 
Subject: Re: [RE-wrenches] What is a "direct-current system"?
From: Peter Parrish 
To: 'Dave Click' 
Date: 2009/6/19 14:12


No, the inspector is saying that 690.47(B) applies, and as a consequence,
250.166 applies. He didn't mention 690.47(C).

Dave,

I see your point: all conventional grid-tied V systems fall under (C). But
(C) refers to its own set of requirements 690.47(C) (1) through (8) and not
250.166. So which to we follow/

- 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: Dave Click [mailto:davecl...@fsec.ucf.edu] 
Sent: Friday, June 19, 2009 10:50 AM

To: peter.parr...@calsolareng.com
Subject: Re: [RE-wrenches] What is a "direct-current system"?

Peter- Do you mean that since there is a DC circuit as well as an AC 
circuit, 690.47(*C*) applies? Then 690.47(C)(7) would require your GEC 
to meet the requirements of 250.66 & 250.166.


I didn't CC the wrenches here, just checking to clarify what you're 
looking for. I assume that 690.47(A) and (B) being separately listed 
like that means that 690.47(A) would apply to anything but DC-direct 
systems, 690.47(B) would apply to everything but AC module systems, and 
then 690.47(C) is there to clarify that you need to worry about both (A) 
and (B) for most systems.


DKC

 Original Message 
Subject: [RE-wrenches] What is a "direct-current system"?
From: Peter Parrish 
To: 'RE-wrenches' 
Date: 2009/6/19 12:55

I have a LA Dept. of B&S inspector cite Article 690.47(B) 
"Direct-Current Systems" and its consequent grounding requirements 
(250.166(A)(B)) in connection with a very straightforward grid tied PV 
system (i.e. no batteries, just PV and a Xantrex GT inverter).


 

He said that since there is a DC circuit as well as an AC circuit, 
690.47(B) applies. I countered that all PV systems have a DC circuit, so 
to separately call out a "Direct-Current System" must apply to something 
other than the DC PV circuit inherent in all PV systems.


 

Am I missing something here? Is "Direct-Current System" defined in 
Article 690? We are working off NEC 2008.


 


Thanks in advance for your help.

 


-  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 <mailto:peter.parr...@calsolareng.com> 
Ph 323-258-8883, Mobile 323-839-6108, Fax 323-258-8885  



 

 





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Re: [RE-wrenches] Inverter AM Interference

[Dave Click]

Weird! I was looking through the list archive for info on lightning 
arrestors earlier this afternoon and coincidentally, this email may 
help, from Aaron Wellendorf on 2006/4/12:

http://lists.re-wrenches.org/htdig.cgi/re-wrenches-re-wrenches.org/2006/019214.html

"I have used a different brand of AC surge arrestor with noise filtering to
quiet the AC line into a grid-tied Trace SW4048 back in 1999. It didn't
completely filter out all noise, but it did make my customer's favorite
680AM radio station listenable vs. a totally static roar. I put them on all
my systems after that, SW or not."

He doesn't say what surge arrestor he uses, but hopefully this helps 
your customer.


DKC

 Original Message 
Subject: [RE-wrenches] Inverter AM Interference
From: solar...@aol.com
To: re-wrenches@lists.re-wrenches.org
Date: 2009/7/14 20:48


Hello:
 
Has anybody got a fix or a way to filter out inverter generated AM 
( 520-700 kHz MW)  noise?  I guess it's never been a problem in the past 
because our customers must not have been fans of AM radio.  Plus, I 
always approved of the fact that it wiped out reception for ditto-heads.
We called SMA and they are in a state of denial.  Our customer is not 
very ambulatory, sits in the same spot most of the day and just loves 
talk radio.  The inverter is more than 30 feet away from the radio.
Other than relocating the inverter (grid-tie, no battery) is there 
anything we can do? 
 
Patrick Redgate

Ameco Solar


Can love help you live longer? Find out now 
.





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Re: [RE-wrenches] Tube solar collectors

[Dave Click]

Yes they do:
http://www.solyndra.com/Products/More-Electricity

 Original Message 
Subject: Re: [RE-wrenches] Tube solar collectors
From: Joel  Davidson 
To: RE-wrenches 
Date: 2009/7/21 09:46


Hello Kelly,

Thanks for the feedback. Does anyone know if the Solyndra CIGS modules 
collect light from the backside?


Joel Davidson

- Original Message - From: "Kelly Keilwitz, Whidbey Sun & Wind" 


To: "RE Wrenches listserve" 
Sent: Monday, July 20, 2009 11:15 PM
Subject: Re: [RE-wrenches] Tube solar collectors



Joel,

We frequently will orient tube collectors on east or west facing roofs 
with
very good results. However, pointing a solar collector toward the 
south will
always produce more energy, as we all know that the greatest solar 
energy is

concentrated around noon.

The choice of whether to tilt comes down to efficiency, cost, and 
aesthetics

- and sometimes overheating issues. With a tube system care must be taken
not to oversize the collector in proportion to the tank. If a customer 
wants

to maximize heating throughout the year I recommend a larger collector
tilted steeply toward the winter sun angle. This not only maximizes 
winter

production but, more importantly, attenuates summer heat gain.

It's interesting to note that, as Apricus tubes have the collector 
surface
circumferentially, they will collect heat from the backside (a 
significant

factor during northern summers).

Another design factor is that the heat pipes must always maintain a slope
for heat transfer. Thus, tilting up on the east or west-facing roof is
necessary if the tubes are to be oriented N-S.

-Kelly
Kelly Keilwitz, P.E.
Whidbey Sun & Wind, LLC
Renewable Energy Systems
NABCEP Certified PV Installer
987 Wanamaker Rd,
Coupeville, WA 98239
PH & FAX 360-678-7131
sunw...@whidbeysunwind.com


On 7/20/09 8:09 AM, "Joel  Davidson"  wrote:


Hello Kelly,

I saw your website photos (nice work). Do you think that tubes 
oriented (1)

east-west would and (2) flat would perform as well as your tilted
north-south tubes?

Joel Davidson

- Original Message -
From: "Kelly Keilwitz, Whidbey Sun & Wind" 
To: "RE Wrenches listserve" 
Sent: Monday, July 20, 2009 12:12 AM
Subject: Re: [RE-wrenches] Tube solar collectors


All,
Apricus ET's have a cylindrical absorber surface, which are 
significantly
better at capturing low angle of incidence energy. I have both a 
Thermomax
(with flat collector plate internal to the tube) and Apricus 
collector in
parallel on my own home and see significantly better temperatures 
early and

late in the day on the Apricus collector.

IMO, ET's have a distinct advantage in our cool, windy, and low-snow
environment (northern Puget Sound).

Kelly Keilwitz, P.E.
Whidbey Sun & Wind, LLC
Renewable Energy Systems
NABCEP Certified PV Installer
987 Wanamaker Rd,
Coupeville, WA 98239
PH & FAX 360-678-7131
sunw...@whidbeysunwind.com





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Re: [RE-wrenches] String Combiners for a-Si modules

[Dave Click]

Peter-

Appendix J of "PV and the NEC" covers this, too; as Kirpal said, you'll 
need to know the series fuse rating for the module first, though.

http://www.nmsu.edu/~tdi/pdf-resources/pdf%20version%20divided%20PV:NEC/APPENDIX%20J.pdf


 Original Message 
Subject: Re: [RE-wrenches] String Combiners for a-Si modules
From: Peter Parrish 
To: 'RE-wrenches' 
Date: 2009/7/21 20:51


EPV Solar EVP-54

The Isc is 1.49 A

The cut sheet does not list a series fuse rating for the module.

But it does say something about being able to use up to 8 in parallel 
without external protection.


I am in the hunt for installation instructions.

 


- 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 *Kirpal 
Khalsa

*Sent:* Tuesday, July 21, 2009 3:11 PM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] String Combiners for a-Si modules

 

Peter...depending on the series fuse rating you might be able to get 
away with more strings in parallel before series fusing is 
requiredwhat panels are they and what is the series fuse rating 
of the modules?
Fronius has a white paper explaining when series fusing is required and 
when you can get by without...it all relates to series fuse rating 
and Isc..the higher the series fuse rating and the lower the Isc the 
more strings you can parallel with out adding series fusing

--
Sunny Regards,
Kirpal Khalsa
NABCEP Certified Solar PV Installer
Renewable Energy Systems
www.oregonsolarworks.com 
541-218-0201 m
541-592-3958 o

On Tue, Jul 21, 2009 at 2:44 PM, Peter Parrish 
mailto:peter.parr...@calsolareng.com>> 
wrote:


We are doing an engineering design for a large scale PV ground mount system
based on a-Si modules. Since the Isc of the modules is 1.5 A, instead of 7-8
A of typical c-Si modules, are there special low-current combiners out
there? Does each string need an overcurrent protection device? Any help with
a-Si based system design would be greatly appreciated.


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



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Re: [RE-wrenches] Watt-hour meter

[Dave Click]

something like this?
http://www.hialeahmeter.com/eawame.html

 Original Message 
Subject: [RE-wrenches] Watt-hour meter
From: Eric Andrews 
To: RE-wrenches@lists.re-wrenches.org
Date: 2009/7/28 13:16

I’m looking for a Watt-hour meter that is hard-wired (not a Kill-O-Watt 
plugin) and resembles a kW-h utility meter for a trade-show display…


 

 


Eric R. Andrews

NABCEP Certified PV Installer

 


Eco Solar, Inc.

www.ecosolarnow.com

 


PO Box 5194

Klamath Falls, OR 97601

541-281-8252 cell

541-273-3200 office

mailto:e...@ecosolarnow.com 

 


/Saving the World...  One Solar Panel at a Time!/

 

 





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Re: [RE-wrenches] High snow load on PV Modules

[Dave Click]

SolarWorld modules are 5400pa-rated too, but that's "only" 113 psf, 
right? These might be OK if you do a full clamp along the long sides of 
the modules (for SolarWorld at least, the 5400pa rating was determined 
per IEC 61215, while supporting only the short sides), but it's 
obviously not without risk.


DKC

 Original Message 
Subject: Re: [RE-wrenches] High snow load on PV Modules
From: David Katz 
To: RE-wrenches 
Date: 2009/7/28 13:19


Tump,
Mitsubishi makes the modules for Shuco with the cross bar.  The sell the 
same module directly.  REC modules are also rated at 5400pa. they do it 
with thicker glass.  Those Norwegians know snow load.

David

David Katz

President

AEE Solar

1155 Redway Drive

P.O. Box 339

Redway, CA  95560

Tel (707) 825-1200

Fax (707) 825-1202

da...@aeesolar.com 

www.aeesolar.com 

 


DISCLAIMER:
This communication, along with any documents, files or attachments, is 
intended for the use of only the addressee and contains privileged and 
confidential information. If you are not the intended recipient, you are 
hereby notified that any dissemination, distribution or copying of any 
information contained in or attached to this communication is strictly 
prohibited.  If you have received this message in error, please notify 
the sender immediately by e-mail reply and destroy the original 
communication and its attachments without reading, printing or saving in 
any manner.


P  Please consider the environment before printing this e-mail.





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Re: [RE-wrenches] "Quick Release" PV System

[Dave Click]

It seems to me that allowing an expensive array to be quickly and easily 
removed from a roof is a Very Bad Thing- I'd guess that the customer's 
insurance company would have an issue with this too. Will they also 
require that heat pumps have wheels and flexible pipes, so that they can 
be moved by firefighters for ladder access? Maybe talking with them 
about the possibility of PV theft could change their mind.

http://www.nytimes.com/2008/09/24/technology/24solar.html

I wonder if this requirement actually came from the fire department. The 
3' buffer around the array (which I thought was standard for CA) makes a 
lot of sense, but I don't see why any firefighters would be interested 
in taking a 5kW, 1500 lbs array off a fiery roof while keeping it 
intact. It's still a lot of work and I don't see any benefit in doing so.


So it's not just you- I think that a "quick release" array is a bad idea 
anywhere where people know that PV is worth a lot of money. And, um, 
that's everywhere.


DKC

 Original Message 
Subject: [RE-wrenches] "Quick Release" PV System
From: Brian White 
To: RE-wrenches 
Date: 2009/7/29 14:18


"Quick Release" PV System

I just had a set of plans rejected by the City of Chula Vista, CA,
because the integrated Tile product that we use did not have a "Quick
Release" System for the array, so that the Fire Department could
remove the array in the event of a fire.

Has anyone ever heard of such a requirement? If so, how did you meet
this requirement, with any style of PV array (BIPV, Standard Modules,
peel & stick) and still achieve an 85 - 100 mph wind rating? Is it
just me, or is this city from a different planet.

This issue did not show up on the initial Plan Correction check list
from the city, but they are calling it out now when we re-submitted.
My electrician asked them to explain it to me over the phone, because
he did not think anyone would believe him when he asked for this
requirement. I have asked for a document or anything that defines
this requirement, and will share what I find out.

Brian C. White Sr. Design Engineer - PV Systems

Eagle Roofing Products 120 North Auburn Street - Suite 212 Grass
Valley, CA  95945 Phone: 530-273-2948 Cell: 530-575-5550





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Re: [RE-wrenches] solid vs stranded AC vs DC

[Dave Click]

2% loss is significant, but I think that Darryl was saying that the 
resistance for stranded wire was 2% higher than solid. So if you had a 
3% voltage drop in your system with stranded wire, you could rewire the 
system with solid wire and have a voltage drop of (3% x 0.98) 2.94% at 
peak production; that's less than 1 kWh/yr per kW installed.


DKC

 Original Message 
Subject: Re: [RE-wrenches] solid vs stranded  AC vs DC
From: Joel  Davidson 
To: RE-wrenches 
Date: 2009/8/3 20:31


2% loss from any resistance source over 25 years is significant.

- Original Message - From: "Darryl Thayer" 
To: "RE-wrenches" 
Sent: Monday, August 03, 2009 2:04 PM
Subject: Re: [RE-wrenches] solid vs stranded AC vs DC



Yes, that is what the code book and my electricians handbook says, but 
2% is very little.  I would think that passing through a conduit hole is 
larger than that.

Darryl

--- On Mon, 8/3/09, Matt Tritt  wrote:


From: Matt Tritt 
Subject: Re: [RE-wrenches] solid vs stranded  AC vs DC
To: "RE-wrenches" 
Date: Monday, August 3, 2009, 3:49 PM






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



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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Check out participant b

Re: [RE-wrenches] PV System Design Compromises (was solid vs stranded AC vs DC)

[Dave Click]

> are we talking about 2% voltage drop, resistance, or power loss?

No- I was talking about the 2% difference in resistance between two 
wires, which is not the same thing as 2% voltage drop. What I got from 
this discussion was that solid copper wire will help your voltage drop 
by about 0.05%, a marginal benefit outweighed by the frustration of 
exclusively using solid wire for wiring.


And sure, keeping losses low and not breaking wire strands at connectors 
are important too. I did an inspection a few weeks ago where we opened 
up the panelboard and the original contractor for the building had 
broken off 3 strands from a #2/0 cable to fit it in the main lugs. Yikes!


DKC

 Original Message 
Subject: [RE-wrenches] PV System Design Compromises (was solid vs 
stranded	AC vs DC)

From: Joel  Davidson 
To: RE-wrenches 
Date: 2009/8/5 14:30

Dave, I agree. but are we talking about 2% voltage drop, resistance, or 
power loss?


What I got from this discussion about solid vs. stranded wire (1) use 
solid copper wire and (2) keep I2R losses low and (3) if you use 
stranded wire, be very diligent when tightening connectors. Anything else?


Wrenches make design compromises every day. My 11 year old grid-tied 
system is an example:

- Siemens SP70 modules because SP75s were unavailable.
- Trace SW4048 at 65% efficiency because higher efficiency non-battery 
inverters were less reliable.
- Low-rise, low-tilt angle array because Culver City did not allow PV 
arrays to be visible from the street.
- And now, making improvements on a system that is working flawlessly 
for almost 100,000 hours does not make cost vs. benefits sense.


Joel Davidson


- Original Message - From: "Dave Click" 
To: "RE-wrenches" 
Sent: Wednesday, August 05, 2009 5:58 AM
Subject: Re: [RE-wrenches] solid vs stranded AC vs DC


2% loss is significant, but I think that Darryl was saying that the 
resistance for stranded wire was 2% higher than solid. So if you had a 
3% voltage drop in your system with stranded wire, you could rewire 
the system with solid wire and have a voltage drop of (3% x 0.98) 
2.94% at peak production; that's less than 1 kWh/yr per kW installed.


DKC

 Original Message 
Subject: Re: [RE-wrenches] solid vs stranded  AC vs DC
From: Joel  Davidson 
To: RE-wrenches 
Date: 2009/8/3 20:31


2% loss from any resistance source over 25 years is significant.

- Original Message - From: "Darryl Thayer" 


To: "RE-wrenches" 
Sent: Monday, August 03, 2009 2:04 PM
Subject: Re: [RE-wrenches] solid vs stranded AC vs DC



Yes, that is what the code book and my electricians handbook says, 
but 2% is very little.  I would think that passing through a conduit 
hole is larger than that.

Darryl

--- On Mon, 8/3/09, Matt Tritt  wrote:


From: Matt Tritt 
Subject: Re: [RE-wrenches] solid vs stranded  AC vs DC
To: "RE-wrenches" 
Date: Monday, August 3, 2009, 3:49 PM






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



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] NEC Art 310 Ampacity

[Dave Click]

You are receiving Wrench list digests. If you are responding to one of the 
messages in the digest, be sure to replace the subject line with the correct 
one for the individual message. Thanks.
Here's a cable that may use B.310.1, which is probably overkill for most 
of our work:

http://www.amercable.com/doc/catalogs/VFDCables.pdf

MC cable requires you to use Table 310.16 for your 600V wires, with a 
few caveats (330.80)


That being said, not sure what "raceway in free air" means. Maybe 
they're trying to draw a distinction between that and underground ducts 
(e.g. Table B.310.5)


Here's the 330.80 section:
***
330.80 Ampacity.
The ampacity of Type MC cable shall be determined in accordance with 
310.15 or 310.60 for 14 AWG and larger conductors and in accordance with 
Table 402.5 for 18 AWG and 16 AWG conductors. The installation shall not 
exceed the temperature ratings of terminations and equipment.
(A) Type MC Cable Installed in Cable Tray. The ampacities for Type MC 
cable installed in cable tray shall be determined in accordance with 
392.11 and 392.13.
(B) Single Type MC Conductors Grouped Together. Where single Type MC 
conductors are grouped together in a triangular or square configuration 
and installed on a messenger or exposed with a maintained free airspace 
of not less than 2.15 times one conductor diameter (2.15 × O.D.) of the 
largest conductor contained within the configuration and adjacent 
conductor configurations or cables, the ampacity of the conductors shall 
not exceed the allowable ampacities in the following tables:

(1) Table 310.20 for conductors rated 0 through 2000 volts
(2) Table 310.67 and Table 310.68 for conductors rated over 2000 volts
***

 Original Message 
Subject: [RE-wrenches] NEC Art 310 Ampacity
From: Peter Parrish 
To: 'RE-wrenches' 
Date: 2009/8/5 16:45


When we do ampacity calculations, we always use Table 310.16 in Section
310.15 for wire in raceway (EMT, PVC, FMC, LNFC, LMFC), and MC cable. Of
course we use Table 310.15(B)(2)(a) in a raceway or cable with more than
three conductors.

A colleague asked me about the applicability of table B.310.1. It would seem
to apply to 2-3 conductors within an overall covering (multi-conductor
cable) in raceway in free air. Would MC apply? But what in the world is a
"cable, in raceway, in free air"?  I'm usually pretty good in parsing this
stuff, but this stumps me.

 
- Peter


Peter T. Parrish, 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


 



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Re: [RE-wrenches] Seasonal Adjusters

[Dave Click]

The only system I've done with this feature, we used 2 Seas (now Iron 
Ridge, it appears) racking. I guess if you can limit those racks to 
being only two modules high, the weight would still be manageable. Still 
not something that one person can easily adjust, though.


Example:
http://www.ironridge.com/files/GroundRoofLandscape/IRONRIDGE_UNI-GR-04.pdf

 Original Message 
Subject: Re: [RE-wrenches] Seasonal Adjusters
From: Darryl Thayer 
To: RE-wrenches 
Date: 2009/8/12 16:51

Thanks William but this is a roof mount.  
Darryl


--- On Wed, 8/12/09, William Miller  wrote:


From: William Miller 
Subject: Re: [RE-wrenches] Seasonal Adjusters
To: "RE-wrenches" 
Date: Wednesday, August 12, 2009, 3:02 PM

 
Darryl:



If this is a ground mount, I recommend a Direct Power top
of Pole
mount. 
http://www.power-fab.com/tpmphotos.htm



The rack is supported at the center of gravity making a
manual
adjustment easy.


William Miller




At 12:49 PM 8/12/2009, you wrote:

He all

I need help designing or buying a seasonal adjuster. 
I have a

customer that insists on a seasonal adjustment.  They
would like 30
degrees summer side of equinox and 50 degrees winter
side.  Wants to
adjust twice a year at equinox.  Rack to be 3 sets of
3 modules each
on two rails.  



Every time I have tried this it is heavy and very difficult
to do. 


Darryl




 



-Inline Attachment Follows-

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[RE-wrenches] DC positive and negative in same conduit, other inspection issues

[Dave Click]

All,

Couldn't find this anywhere in the archives; sorry if it's a repeat. I 
just went out to inspect a ground-mount system that had 3 source 
circuits feeding a metal DC combiner/disconnect. Wiring was free air 
until it got near the disconnect, then the positive wires entered an 
open 3' section of FNMC (no strain relief or box at the other end of the 
FNMC). The negative wires ran through a *separate* 3' section of FNMC. 
The array had N-S-run support rails, and along the top of each rail was 
run a #6 bare continuous through Wiley lugs that ran to a ground rod on 
the west end. This #6 bare used split bolts to connect #6 bare taps to 
the disconnect switches, with the #6 bare entering a separate knockout 
from the positive and negative wiring conduits, with strain relief 
provided by... a romex cable clamp. This was then repeated on the rest 
of the 75kW array.


So I found the following corrections:

1. Running the positive and negative wires through separate conduit 
violates 300.3, and could cause eddy currents in the combiner/disc boxes.
2. Running the equipment ground separately from the +/- wiring is also 
not code compliant
3. Using romex cable clamps for something other than Romex is also less 
than correct, and I imagine that has some effect on the UL listing or 
warranty of the NEMA 3R box (at least the clamp is in a bottom knockout, 
but still)
4. When entering the open conduit with USE-2 home runs, you need to have 
some kind of strain relief; I usually recommend liquid-tight cord grips, 
against the wishes of 98% of the installers that I speak with.


For the grounding electrode wiring, it seems that it's fine to me since 
they ran the continuous #6 to each rail and then to the rod, qualifying 
as the 690.47(D) supplemental electrode. But the split bolts tapping 
that GEC to "ground the disconnect," these are required to be 
irreversible connections to the ground bus in that disconnect, right?


Did I miss anything? Thanks for reading this far and for the backup.

Thanks,
DKC
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Re: [RE-wrenches] DC positive and negative in same conduit, other inspection issues

[Dave Click]

Thanks all.

It was my understanding that we should still be running the conductors 
of the same circuit through the same raceway, even if it is the DC input 
into the inverter since that DC oscillates slightly (nowhere near as 
much as AC). I wasn't concerned about eddy currents in the FNMC of 
course but the metal box itself, a concern being voiced on this list 
before. I'd be more concerned about this if it were a 1MW inverter 
rather than a 7kW, but still.


Thanks for the info on the GEC tap and I'm glad the split bolts work here.

The conduit in question doesn't seem to be there just for physical 
protection; the wire runs from the east end of the array for 100'+ and 
only the last 3' are in conduit. If it were only for protection I'd be 
fine with it being open-ended on both ends, but since it's there to feed 
the conductors into the box, that's why I was treating it as a regular 
conduit that required a cord grip at the other end. Where do others make 
the distinction?


Thanks,
DKC

 Original Message 
Subject: Re: [RE-wrenches] DC positive and negative in same conduit, 
other inspection issues

From: Kelly Keilwitz, Whidbey Sun &  Wind 
To: RE Wrenches listserve 
Date: 2009/8/19 21:10


Dave,
Only GEC's are subject to the "continuous" rule (250.64C). It sounds like
your are talking about an EGC tapped from the GEC.

When splicing PV GEC's required under 690.47D, either together (from
separated arrays) or to the existing AC GEC (if close enough), we have been
allowed to use split bolts instead of irreversible splices, per 250.64D1,
"Grounding Electrode Conductor Taps" (at end of paragraph). I.E., the
"continuous" rule is only being applied to the main GEC.

I agree with Kurt on the LTNMF being used only as extra (not required) wire
protection for the USE-2. We often do this when running PV conductors
between short separations in modules or rails. I would think that only
temperature and fill corrections would apply - and only if the length
requires.

-Kelly

Kelly Keilwitz, P.E.
Whidbey Sun & Wind, LLC
Renewable Energy Systems
NABCEP Certified PV Installer
987 Wanamaker Rd, 
Coupeville, WA 98239

PH & FAX 360-678-7131
sunw...@whidbeysunwind.com

On 8/19/09 2:41 PM, "Dave Click"  wrote:


For the grounding electrode wiring, it seems that it's fine to me since
they ran the continuous #6 to each rail and then to the rod, qualifying
as the 690.47(D) supplemental electrode. But the split bolts tapping
that GEC to "ground the disconnect," these are required to be
irreversible connections to the ground bus in that disconnect, right?



 




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Re: [RE-wrenches] ballasted roof rack - on the ground?

[Dave Click]

I think that the 250kW Florida Power & Light array in Sarasota, FL was 
installed on a ground cover (over a landfill) like the SIT solution, and 
that it was just done with PowerGuard.


 Original Message 
Subject: Re: [RE-wrenches] ballasted roof rack - on the ground?
From: Joel  Davidson 
To: RE-wrenches 
Date: 2009/8/21 10:14


Geoff,
 
Solar Integrated Technologies adheres its panels on ground covers 
over landfills to capture landfill gases and separately produce PV 
electricity. Perhaps a wrench with Powerlight experience can tell us why 
rigid modules are not laid on a ground cover.
 
Joel Davidson


- Original Message -
*From:* Geoff Greenfield <mailto:ge...@third-sun.com>
*To:* RE-wrenches <mailto:re-wrenches@lists.re-wrenches.org>
*Sent:* Thursday, August 20, 2009 8:35 PM
*Subject:* [RE-wrenches] ballasted roof rack - on the ground?

esteemed wrenches (or just steamed if youve been out in the hot lately)

I'm curious why more folks don't use the same flat roof ballasted
rack approach for large ground mounts?  Geotech weed barier and off
we go...  my initial calcs sat its a cost saver... my instinct says
it viable, but my other instinct says "if it were this easy I would
see it all the time (and I've never seen it)

what's up?  frost heave/instability?  wav-i-ness of the ground?
better performance at steep angle worth all the extra cost (not
according to my pencil with today's mod costs).  Thoughts? 


For a brighter energy future,

Geoff Greenfield
President
Third Sun Solar & Wind Power Ltd.
340 West State Street, Unit 25
Athens, OH 45701

740.597.3111 Fax 740.597.1548
www.Third-Sun.com

Clean Energy - Expertly Installed






- "Dave Click"  wrote:
 > Thanks all.
 >
 > It was my understanding that we should still be running the
conductors
 > of the same circuit through the same raceway, even if it is the
DC input
 > into the inverter since that DC oscillates slightly (nowhere near as
 > much as AC). I wasn't concerned about eddy currents in the FNMC of
 > course but the metal box itself, a concern being voiced on this list
 > before. I'd be more concerned about this if it were a 1MW inverter
 > rather than a 7kW, but still.
 >
 > Thanks for the info on the GEC tap and I'm glad the split bolts
work here.
 >
 > The conduit in question doesn't seem to be there just for physical
 > protection; the wire runs from the east end of the array for
100'+ and
 > only the last 3' are in conduit. If it were only for protection
I'd be
 > fine with it being open-ended on both ends, but since it's there
to feed
 > the conductors into the box, that's why I was treating it as a
regular
 > conduit that required a cord grip at the other end. Where do
others make
 > the distinction?
 >
 > Thanks,
 > DKC
 >
 >  Original Message 
 > Subject: Re: [RE-wrenches] DC positive and negative in same conduit,
 > other inspection issues
 > From: Kelly Keilwitz, Whidbey Sun &  Wind 
 > To: RE Wrenches listserve 
 > Date: 2009/8/19 21:10
 >
 > > Dave,
 > > Only GEC's are subject to the "continuous" rule (250.64C). It
sounds like
 > > your are talking about an EGC tapped from the GEC.
 > >
 > > When splicing PV GEC's required under 690.47D, either together
(from
 > > separated arrays) or to the existing AC GEC (if close enough),
we have been
 > > allowed to use split bolts instead of irreversible splices, per
250.64D1,
 > > "Grounding Electrode Conductor Taps" (at end of paragraph).
I.E., the
 > > "continuous" rule is only being applied to the main GEC.
 > >
 > > I agree with Kurt on the LTNMF being used only as extra (not
required) wire
 > > protection for the USE-2. We often do this when running PV
conductors
 > > between short separations in modules or rails. I would think
that only
 > > temperature and fill corrections would apply - and only if the
length
 > > requires.
 > >
 > > -Kelly
 > >
 > > Kelly Keilwitz, P.E.
 > > Whidbey Sun & Wind, LLC
 > > Renewable Energy Systems
 > > NABCEP Certified PV Installer
 > > 987 Wanamaker Rd,
 > > Coupeville, WA 98239
 > > PH & FAX 360-678-7131
 > > sunw...@whidbeysunwind.com
 > >
 > > On 8/19/09 2:41 PM, "Dave Click"  

Re: [RE-wrenches] Solar and pumped hydro

[Dave Click]

I'd had this question a while ago, and thought I'd send a few links I 
found last year in case they're helpful for anyone.


http://www.renewableenergyworld.com/rea/news/article/2008/03/pumped-storage-to-back-up-renewable-energy-51745
from that page:
1994 IEEE Study on reservoir size requirements (sorry, I'm not an IEEE 
member so I can't send this paper your way)

http://ieeexplore.ieee.org/Xplore/login.jsp?url=/iel1/59/7653/00317595.pdf?arnumber=317595

2005 Power and Technology Magazine article on required site indices for 
pumped storage

http://www.springerlink.com/content/q250m7930q5407w0/

D. Manolakos, G. Papadakis, D. Papantonis and S. Kyritsis; A stand-alone
photovoltaic power system for remote villages using pumped water energy 
storage; Energy, Volume 29, Issue 1, January 2004, Pages 57-69.

http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V2S-49PRFMP-
7&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C50221&_version=1
&_urlVersion=0&_userid=10&md5=9d6b2fba77001e9649de77a59f616812

 Original Message 
Subject: Re: [RE-wrenches] Solar and pumped hydro
From: Mark Dickson 
To: 'RE-wrenches' 
Date: 2009/8/25 09:41


Keith,

This has been a novel idea that I have heard many times lately, but it 
just does not pencil out--maybe on the utility scale, but not on the 
micro-hydro scale.


Take for instance my micro-hydro scenario.  I have a 75’ head with a 
Stream Engine at the bottom with two ½” nozzles. When both nozzles are 
fully open I have about 80gpm flowing through the system.  This results 
in ~670 watts before wire, battery and inverter losses.


 

Now take away my stream and design a solar pump system.  I could put in 
a Lorentz PS1800 system with a 1600watt array that would pump about 
15,000 gallons/day (non-tracked) in the summer up the 75’ for about 
$12,000. 

 

15,000gallons of water (not taking evaporation into consideration) would 
then run my turbine for 3.1hours, producing only 2,077 watts!


 


My four L16s that I use as a “buffer” have more storage than that.

 

I think our best bet it to hold off for some reasonable flow-batteries 
or the fuel cell.


 


Best regards,

 


Mark Dickson

Oasis Montana Inc.

 

 




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

*Sent:* Monday, August 24, 2009 7:44 PM
*To:* 'RE-wrenches'
*Subject:* Re: [RE-wrenches] Solar and pumped hydro

 


Hi Keith,

 

That is my place. Hydro pond is both spring fed and fed by a small 
seasonal brook, no pumping.


 

I figure approximately  50% to55% efficiency for a high head micro-hydro 
turbine (Harris PM), not including, wire, batteries and inverter losses. 
I do not know the efficiency of larger turbines. Check with Canyon 
Industries (they advertise in Home Power). I’ve heard that they are 
significantly higher in efficiency (before transmission losses).


 

I have heard that at least one larger scale hydro facility in NY State 
pumps back to the reservoir overnight at off peak rates, then releases 
generation water during peak rate periods. Also, Hydro Quebec buys off 
peak power from the U.S. grid when it’s dirt cheap to power Montreal 
overnight. This saves some of their own water power for selling  to  the 
States during peak periods. A nice money making deal for Quebec. So, 
your idea is worth thinking about for regions such as Hawaii I believe.


 


Dave

 

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

*Sent:* Monday, August 24, 2009 2:43 PM
*To:* RE-Wrenches
*Subject:* [RE-wrenches] Solar and pumped hydro

 


Hi

Have any of you considered using PV to pump water to a holding area and 
releasing it and capturing the kinetic energy via a pelton wheel/hydro?


If so, what do we think are the efficiencies and value of doing such a 
project are? Meaning, back of the napkin, PV is + - 77% efficient, minus 
"x" to pump the water to "x" elevation and the net result of the hydro = 
"% efficient"


It would be using the reservoir as the battery.

There is approximately 300' of elevation from the PV system and water 
source to the reservoir area.


I recall about 15 years ago, I visited a member on this lists Vermont 
home and he had a pond at the top of his property, but i don't recall 
how the source got to the reservoir? Might have been naturally fed?


Anyway, the premise is, as grid access becomes more difficult to do, as 
the utility infrastructure gets saturated, what are our options for 
folks that want PV, but are limited in how much they are allowed to 
connect to the grid, without an interconnection study by a 3rd party to 
increase the comfort of the utility to have more non firm resources on 
their grid. We are seeing this happen here now and I was wondering if 
any of you have encountered this or are an

Re: [RE-wrenches] FW: Advanced Solar Photonics

[Dave Click]

I've heard of them and they are new. I don't think they're making them 
in Florida yet but they claim to be US-made. I think that on the 
previous edition of their website they were planning an 800W crystalline 
module(!), now they seem to have scaled back to "only" a 600W sometime 
next year.


They're not on the CEC/CSI list or the FSEC certified module list yet, 
so I'd double-check that they have their UL listing before ordering any.



 Original Message 
Subject: [RE-wrenches] FW: Advanced Solar Photonics
From: Allan Sindelar 
To: 'RE-wrenches' 
Date: 2009/8/27 09:16


Wrenches,
Anyone heard of this company? It showed up in my junk email folder, but it
appears to be legit: A new manufacturer of UL 1703 monocrystalline 210W 60
cell modules, U.S.-made and located in Florida. They're probably really
hurting as a startup with lots of capital investment, offering modules
cheaply to compete with the Chinese.
Thanks 


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: SugarCRM [mailto:no_re...@crm.asp.local] 
Sent: Thursday, August 27, 2009 12:01 AM

To: Allan Sindelar
Subject: Advanced Solar Photonics -- Solar PV SALE!!

Hello, 


I am reaching out to you because I was told that you are a certified solar
installer, and might be interested in our reduced priced panels.  Advanced
Solar Photonics is a monocrystalline solar panel manufacturer in Lake Mary,
FL and we have recently ramped up the production of our first assembly line.
Because we are manufacturing panels, we are forced to sell the overstocked
panels that we have in our warehouse to make room for the newly assembled
panels.  These panels are 210 watt panels with full UL and CSC
certification.  Because we want to get rid of the panels as fast as
possible, we are offering the sale price of $2.15/watt per container load
orders.  We are selling these panels nearly at cost, but we need to make
room for our own panels in our warehouse.  


If you are interested in taking advantage of these sale prices, please feel
free to contact me via phone or email.  Upon contact, I will provide the
specs of the panels and we can complete your order within a matter of days.
I look forward to hearing from you. 


Thanks,
Kyle T. Morse
Sales Manager
Advanced Solar Photonics 
 
400 Rinehart Rd Ste. 1060

Lake Mary, FL 32746 USA
tel: 407-804-1000 x 507 Fax: 407-333-9143

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Re: [RE-wrenches] Direct Grid Tie Upgrade - drawing attached

[Dave Click]

Carl, it looks like you're already Code-noncompliant thanks to the 100A 
garage panel having 100A utility, 20A PV, and 20A wind breakers 
supplying it. Adding an additional 20A of PV of course doesn't help 
things. I'd replace the 100A panel with a 150A+ (so probably a 200A), 
keeping the 100A main.


100A utility + 20A PV + 20A wind + 20A new PV = 160A < 200A bus

I'd get into 2005 vs 2008 NEC breaker issues here, but it's apparent 
that the local inspector doesn't care!


I'd also suggest that you tie all your electrodes together, contrary to 
what's shown in your schematic. Cue the discussion of ground loops.


DKC

 Original Message 
Subject: [RE-wrenches] Direct Grid Tie Upgrade - drawing attached
From: Carl Adams 
To: RE-wrenches@lists.re-wrenches.org
Date: 2009/9/2 15:11


Hello Wrenches,

I have a prospect who has an existing PV system and a small wind
turbine already in place.  He is interested in adding additional
capacity via another small grid tie system.  The attached drawing
outlines the existing and proposed installation.  My question has to
do with the grid tie in.  Given the existing connections for the 2
existing DGT inverters can I connect as proposed in the drawing or
would I need to perform a line side tap on the primary feed.

Alternative suggestions appreciated.

Carl Adams
SunRock Solar, LLC




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[RE-wrenches] 14 PV-Powered Fans- best method?

[Dave Click]

Hi all,

I'm working on a project for a state park, where they're looking to add 
some PV-powered fans to a outdoor bus stop. The customer is hoping to 
have the fans spin more quickly as irradiance increases, and they want a 
master cutoff switch. I'm initially planning to use 2 10W modules 
(series to 24V) powering each of 14 Nextek (http://www.nextekpower.com/) 
DC-powered Gossamer fans, since that seemed to be the easiest way.


However, I'd like something that looks better than 30 of those small 
modules (best 10W module I found that can do 24V is series-connected 
Sunwize modules with semicircle cells) up there on the roof. I was 
thinking about having a 24V module or two up there that backfeeds the 
output of a 14-pole source circuit combiner, with each pole a 1A breaker 
feeding a fan. Then I got concerned that if a breaker or two ever 
tripped (hopefully each fan presents an equal load to the PV, but 
still), the remaining breakers would trip as it tried to feed 200W 
through fewer and fewer loads.


Any recommended method for implementing this, and for installing the 
cutoff switch in the first scenario? For the second scenario, I'd 
probably just use an unfused safety switch on the PV output.


Thanks,
Dave
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Re: [RE-wrenches] Report-Guidelines for Roof-mounted PV System Installations

[Dave Click]

The original code citation here was directed toward large rooftop unit 
(RTU) air conditioners and other large equipment that can not be 
disconnected without extensive cost and disruption to the building 
occupants during re-roofing. Hopefully this helps someone in case they 
have this imposed as a requirement on their future work, but Miami-Dade, 
Broward Board of Codes and Appeals provided an interpretation that this 
code requirement would NOT apply to PV and thermal systems if they could 
be installed in a manner that would allow the system to be readily 
removed and reinstalled for re-roofing purposes.


Sorry that sounds subjective, but hopefully no one will actually 
encounter this. It would be a shame to see this imposed right as BIPV 
[finally] takes off... especially if that inspector also requires you to 
install a handrail around the roof perimeter. I'm guessing that BIPV is 
not addressed within this "first attempt" report.


DKC

 Original Message 
Subject: [RE-wrenches] Report-Guidelines for Roof-mounted PV System 
Installations

From: benn kilburn 
To: re-wrenches@lists.re-wrenches.org
Date: 2009/11/2 13:08


Wrenches,
Just an FYI.

 I just had a chat with someone at the National Roofing Contractors 
Assoc. and they made me aware of this report they just released.

http://www.nrca.net/rp/pubstore/details.aspx?c=12&id=526

Apparently this report concludes that PV arrays being installed on a 
homes' roof should be installed on stand-offs high enough for roofers to 
work around and under!  I got the impression from the person i spoke 
with that they did not include any PV installers in their resource list 
for this report.  They did assert that is a 'first attempt' at this type 
of report.


I am not endorsing this report in any way, i just want the Wrenches to 
be aware of it.


Cheers,
benn

DayStar Renewable Energy Inc. 
bennkilb...@hotmail.com 
780-906-7807 
HAVE A SUNNY DAY


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Re: [RE-wrenches] 2009 Federal Tax Credit Clarification

[Dave Click]

This may help, from a SEIA webinar in September. To answer your 
question: "It depends." (sorry!) See pages 13-15.

http://www.seia.org/galleries/pdf/SEIA%20Tax%20Basis%20Webinar%209%2024%2009%20%5BCompatibility%20Mode%5D.pdf


 Original Message 
Subject: Re: [RE-wrenches] 2009 Federal Tax Credit Clarification
From: wind...@wind-sun.com 
To: RE-wrenches 
Date: 2009/11/2 11:32

With tax season coming up, we are getting inquiries about how the 
federal tax credit works.


My reading on what little info the IRS has is that the 30% credit can be 
taken only on your actual out of pocket expenses - that is, full cost of 
the system minus any other rebates, incentive, or grants.


But a few of our customers are telling us that they are being told by 
some that the full 30% credit applies no matter what other incentives 
they might get. That does not make sense to me, but I can find nothing 
on the IRS site or anyplace else that really addresses that issue.


Does anyone have some actual documented info on this?

.. 


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


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Re: [RE-wrenches] Costs of Solar Permits

[Dave Click]

http://www.rules.house.gov/111/AmndmentsSubmitted/hr2454/cardoza173_hr2454_111.pdf

Back in June, I found this amendment to the Waxman-Markey Cap and Trade 
bill- limiting solar permit costs for residential at $500 and 
noncommercial at 1% of the project cost, up to $10k. Noncompliance with 
permit cost requirements would disqualify the entity from Community 
Development Block Grants. I don't think it made it into the latest 
version, but you Californians should let Cardoza know that he's doing 
good work! This is the only time I've seen this addressed at the federal 
level.


DKC

 Original Message 
Subject: Re: [RE-wrenches] Costs of Solar Permits
From: Michael Welch 
To: RE-wrenches 
Date: 2009/10/29 16:21


Hi Nick. Here is some info you may find helpful, or at least interesting.

http://www.lomaprieta.sierraclub.org/TheLomaPrietan.asp?q=2009050101

Nick Soleil wrote at 12:45 PM 10/29/2009:
 

Aloha wrenches:
   I will be involved in a few meetings with City Council members and Building 
Officials around Sonoma County, CA, and I want to argue that solar permit fees 
should be lower.  Do any of you have recommendations for me?  I want to argue 
that the solar provides other incentives to the jurisdictions besides the 
incomes from the permit fees, such as; city taxes collected, environmental 
benefits, reliable electric system, etc.
. Nick Soleil
Project Manager


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Re: [RE-wrenches] Bonding Rails

[Dave Click]

Peter,

(1) it appears that per the WEEB installation manual:
http://www.we-llc.com/Datasheets/104-0404-08-008.pdf
(page 8) you need to have one WEEB per module rather than one for every 
other module as you suggest.


(2) 690.43 Equipment Grounding.
Exposed non–current-carrying metal parts of module frames, equipment, 
and conductor enclosures shall be grounded in accordance with 250.134 or 
250.136(A) regardless of voltage.


I guess the latter answer depends on whether your AHJ considers the 
rails "exposed"-- I would, so in this situation I'd have lugs on each 
module and each rail.


DKC

 Original Message 
Subject: [RE-wrenches] Bonding Rails
From: Peter Parrish 
To: 'RE-wrenches' 
Date: 2009/11/17 14:56

We have been using WEEB clips on all of our installations for over a 
year now. We include the WEEB data/installation sheets in our permit 
package and patiently point out the clips to inspectors who haven’t seen 
the WEEB system yet.


 


Two questions:

 

(1) For ProSolar rails, can we use one WEEB clip to bond two 
adjacent modules (say, modules A and B) on the upper rail (say, rail #1) 
and then use a second WEEB clip to bond the next two adjacent modules 
(say, modules C and D) on the lower rail (say, rail #2) and then use a 
listed lay-in lug (with in our case a WEEB clip) to bond to either rail 
#1 or #2 to continue the grounding?


(2) If we DON”T use WEEB clips and use the conventional bonding 
methodology per module manufacturer’s instructions (proper location on 
the module, and listed screws, washers and nuts), do we have to ALSO 
bond the rails? We have an inspector in Pasadena, CA that is requiring 
this, but this is the first time we have been required to do so. Perhaps 
in the past year in ignorant bliss we have missed an important 
development? Or have we been dodging bullets for seven years and not 
even knowing it?


 


- 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 
  

 

 





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Re: [RE-wrenches] Bonding Rails

[Dave Click]

Yes, that's correct. In my answer I was just rephrasing it to say you'd 
need twice as many WEEBs as you think. As I understand it, the intent of 
this layout is to give the installer two chances to bond each module 
properly to the rail.


Unirac has a similar requirement for its UGC-1s on SolarMount, but in 
their schematic they don't require you to bond to both rails. So if you 
have four modules, you need UGC-1s between A&B, B&C, C&D but you can 
have them all on a single rail. I think it's better to alternate between 
rails anyway: A&B (top rail), B&C (bottom rail), etc.


DKC

 Original Message 
Subject: Re: [RE-wrenches] Bonding Rails
From: Peter Parrish 
To: 'RE-wrenches' 
Date: 2009/11/17 15:55


On page 8 it would appear that we need TWO WEEB clips bonding modules A and
B to rails #1 and #2 and another TWO WEEB clips bonding modules C and D to
rails #1 and #2, etc. - Peter

-Original Message-
From: re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Dave Click
Sent: Tuesday, November 17, 2009 12:14 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] Bonding Rails

Peter,

(1) it appears that per the WEEB installation manual:
http://www.we-llc.com/Datasheets/104-0404-08-008.pdf
(page 8) you need to have one WEEB per module rather than one for every 
other module as you suggest.


(2) 690.43 Equipment Grounding.
Exposed non-current-carrying metal parts of module frames, equipment, 
and conductor enclosures shall be grounded in accordance with 250.134 or 
250.136(A) regardless of voltage.


I guess the latter answer depends on whether your AHJ considers the 
rails "exposed"-- I would, so in this situation I'd have lugs on each 
module and each rail.


DKC

 Original Message 
Subject: [RE-wrenches] Bonding Rails
From: Peter Parrish 
To: 'RE-wrenches' 
Date: 2009/11/17 14:56

We have been using WEEB clips on all of our installations for over a 
year now. We include the WEEB data/installation sheets in our permit 
package and patiently point out the clips to inspectors who haven't seen 
the WEEB system yet.


 


Two questions:

 

(1) For ProSolar rails, can we use one WEEB clip to bond two 
adjacent modules (say, modules A and B) on the upper rail (say, rail #1) 
and then use a second WEEB clip to bond the next two adjacent modules 
(say, modules C and D) on the lower rail (say, rail #2) and then use a 
listed lay-in lug (with in our case a WEEB clip) to bond to either rail 
#1 or #2 to continue the grounding?


(2) If we DON"T use WEEB clips and use the conventional bonding 
methodology per module manufacturer's instructions (proper location on 
the module, and listed screws, washers and nuts), do we have to ALSO 
bond the rails? We have an inspector in Pasadena, CA that is requiring 
this, but this is the first time we have been required to do so. Perhaps 
in the past year in ignorant bliss we have missed an important 
development? Or have we been dodging bullets for seven years and not 
even knowing it?


 


- 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 <mailto:peter.parr...@calsolareng.com> 
Ph 323-258-8883, Mobile 323-839-6108, Fax 323-258-8885 



 

 





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Options &

Re: [RE-wrenches] SWR2500U Inverter

[Dave Click]

Just a note here- rather than using the record lows, you can go back to 
the future and use the ASHRAE minimum expected temperatures as the 2011 
NEC will allow explicitly. In the '08, it says to use the "lowest 
expected ambient temperature," for which the ASHRAE temperatures are 
more appropriate than record lows. These ASHRAE temps will be higher 
than the record lows and will add a little more cushion there at 600 VDC.


So where to get these temperatures? Starting on page 47:
http://www.solarabcs.org/permitting/Expermitprocess.pdf

Also, in case you didn't know, www.pvselect.com is another option for 
string sizing that features multiple inverters and a 1 degree 
temperature step rather than the 9 degree (F) temperature step on the 
SMA sizer. They have the Kyocera KD130 in their database, but not the KC130.


DKC

 Original Message 
Subject: Re: [RE-wrenches] SWR2500U Inverter
From: Brian Teitelbaum 
To: RE-wrenches 
Date: 2009/11/18 01:34


Joel,
 
The SMA SWR2500U inverter has been a long discontinued model. If you 
want to use an SMA inverter, go to the SMA website to use their 
excellent sizing program. Plug in the module, and your record minimum 
and average maximum temps for the site, and look for a current model 
inverter that will work. All of the "U" series inverters (except for the 
700U) are discontinued models, and the "US" series are the current models.
 
If your min temp is not below 14⁰F, it looks like you can use all 24 in 
one series string with the 4000US inverter, but that gets you awfully 
close to 600VDC (595VDC) at 14⁰F. You might want to play it safe and 
drop one of the modules. Unfortunately, none of the SMA inverters will 
operate with only 12 modules in a string (with two strings). However, a 
Fronius IG-3000 will, so you might want to go with that, although it has 
a lower efficiency.
 
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 Joel 
Davidson

Sent: Tuesday, November 17, 2009 4:56 PM
To: RE-wrenches
Subject: [RE-wrenches] SWR2500U Inverter
 
Wrenches,
 
Our customer has 24 each Kyocera KC130 modules and wants to go grid-tied.

Can he use an SMA SWR2500U inverter with the fan kit? Is there a better
inverter that will use all of his modules? If you have an SWR2500U or a
better inverter option for sale, please contact me off-list. Thank you very
much.
 
Joel Davidson
 
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Re: [RE-wrenches] Bonding Rails

[Dave Click]

Kirpal, it looks like Unirac needs to make their requirement consistent- 
I was using

http://www.unirac.com/pdf/ii227.pdf (dated Sep '09)
as my source which differs from your source (dated Feb '09)

I like your 225_5 layout better, though. The more grounding the merrier.

 Original Message 
Subject: Re: [RE-wrenches] Bonding Rails
From: Kirpal Khalsa 
To: RE-wrenches 
Date: 2009/11/17 19:29

Hey GuysUnirac recently changed their requirement to 2 clips between 
each module...one on the upper rail and one on the lower 
rail..therefore by my count you need 2N-2 clips for N modules, you 
don't need any clips at the ends of the row of modules   the 
link to their diagram and instructions is:  
http://www.unirac.com/pdf/ii225_5.pdf



I think the overall intention is that it is better to not skimp on 
grounding.for all the inner modules in a row they are bonded to the 
rails at 4 points, each of the rails has a ground lug.  Should any 
module be removed for any reason the remainder of the modules are still 
solidly grounded..


My understanding is that Uniracs ground lugs and clips are licensed from 
Wiley so I would guess that the Wiley direct ground lugs and clips have 
the same requirements..


My take is that this grounding system is soo much more convenient 
and fast than some of the ground lug to module systems we used to 
use...(and still use in top of pole mounts)...

Cheers,

--
Sunny Regards,
Kirpal Khalsa
NABCEP Certified Solar PV Installer
Renewable Energy Systems
www.oregonsolarworks.com <http://www.oregonsolarworks.com>
541-218-0201 m
541-592-3958 o

On Tue, Nov 17, 2009 at 1:47 PM, Peter Parrish 
mailto:peter.parr...@calsolareng.com>> 
wrote:


That still works to approximately one clip per rail (actually N-1
clips for
N modules). - 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 <mailto: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>
[mailto:re-wrenches-boun...@lists.re-wrenches.org
<mailto:re-wrenches-boun...@lists.re-wrenches.org>] On Behalf Of
Dave Click
Sent: Tuesday, November 17, 2009 1:09 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] Bonding Rails

Yes, that's correct. In my answer I was just rephrasing it to say you'd
need twice as many WEEBs as you think. As I understand it, the intent of
this layout is to give the installer two chances to bond each module
properly to the rail.

Unirac has a similar requirement for its UGC-1s on SolarMount, but in
their schematic they don't require you to bond to both rails. So if you
have four modules, you need UGC-1s between A&B, B&C, C&D but you can
have them all on a single rail. I think it's better to alternate between
rails anyway: A&B (top rail), B&C (bottom rail), etc.

DKC

 Original Message 
Subject: Re: [RE-wrenches] Bonding Rails
From: Peter Parrish mailto:peter.parr...@calsolareng.com>>
To: 'RE-wrenches' mailto:re-wrenches@lists.re-wrenches.org>>
Date: 2009/11/17 15:55

 > On page 8 it would appear that we need TWO WEEB clips bonding
modules A
and
 > B to rails #1 and #2 and another TWO WEEB clips bonding modules C
and D to
 > rails #1 and #2, etc. - Peter
 >
 > -Original Message-
 > From: re-wrenches-boun...@lists.re-wrenches.org
<mailto:re-wrenches-boun...@lists.re-wrenches.org>
     > [mailto:re-wrenches-boun...@lists.re-wrenches.org
<mailto:re-wrenches-boun...@lists.re-wrenches.org>] On Behalf Of
Dave Click
 > Sent: Tuesday, November 17, 2009 12:14 PM
 > To: RE-wrenches
 > Subject: Re: [RE-wrenches] Bonding Rails
 >
 > Peter,
 >
 > (1) it appears that per the WEEB installation manual:
 > http://www.we-llc.com/Datasheets/104-0404-08-008.pdf
 > (page 8) you need to have one WEEB per module rather than one for
every
 > other module as you suggest.
 >
 > (2) 690.43 Equipment Grounding.
 > Exposed non-current-carrying metal parts of module frames, equipment,
 > and conductor enclosures shall be grounded in accordance with
250.134 or
 > 250.136(A) regardless of voltage.
 >
 > I guess the latter answer depends on whether your AHJ considers the
 > rails "exposed"-- I would, so in this situation I'd have lugs on each
 > module and each rail.
 >
 > DKC
 >
 >  

Re: [RE-wrenches] SWR2500U Inverter

[Dave Click]

Good catch Bob, there seems to be a page missing from that table... this 
report from Bill's site has the complete table (at the end of the file, 
again).


http://www.brooksolar.com/files/Expedited_Explanation-5-6-09.pdf

DKC

 Original Message 
Subject: Re: [RE-wrenches] SWR2500U Inverter
From: robert ellison 
To: RE-wrenches 
Date: 2009/11/18 11:01

My eyes must be bad, i just looked at the entire list 3 times and New 
York state is not on it anywhere.
 
I have see 48 below and just wanted to see what the averages ctually were.
 
Bob


On Wed, Nov 18, 2009 at 7:30 AM, Dave Click <mailto:davecl...@fsec.ucf.edu>> wrote:


Just a note here- rather than using the record lows, you can go back
to the future and use the ASHRAE minimum expected temperatures as
the 2011 NEC will allow explicitly. In the '08, it says to use the
"lowest expected ambient temperature," for which the ASHRAE
temperatures are more appropriate than record lows. These ASHRAE
temps will be higher than the record lows and will add a little more
cushion there at 600 VDC.

So where to get these temperatures? Starting on page 47:
http://www.solarabcs.org/permitting/Expermitprocess.pdf

Also, in case you didn't know, www.pvselect.com
<http://www.pvselect.com/> is another option for string sizing that
features multiple inverters and a 1 degree temperature step rather
than the 9 degree (F) temperature step on the SMA sizer. They have
the Kyocera KD130 in their database, but not the KC130.

DKC


 Original Message 
Subject: Re: [RE-wrenches] SWR2500U Inverter
From: Brian Teitelbaum mailto:bteitelb...@aeesolar.com>>
To: RE-wrenches mailto:re-wrenches@lists.re-wrenches.org>>
Date: 2009/11/18 01:34

Joel,
 The SMA SWR2500U inverter has been a long discontinued model.
If you want to use an SMA inverter, go to the SMA website to use
their excellent sizing program. Plug in the module, and your
record minimum and average maximum temps for the site, and look
for a current model inverter that will work. All of the "U"
series inverters (except for the 700U) are discontinued models,
and the "US" series are the current models.
 If your min temp is not below 14⁰F, it looks like you can use
all 24 in one series string with the 4000US inverter, but that
gets you awfully close to 600VDC (595VDC) at 14⁰F. You might
want to play it safe and drop one of the modules. Unfortunately,
none of the SMA inverters will operate with only 12 modules in a
string (with two strings). However, a Fronius IG-3000 will, so
you might want to go with that, although it has a lower efficiency.
 Brian Teitelbaum
AEE Solar
   -Original Message-
From: re-wrenches-boun...@lists.re-wrenches.org
<mailto:re-wrenches-boun...@lists.re-wrenches.org>
[mailto:re-wrenches-boun...@lists.re-wrenches.org
<mailto:re-wrenches-boun...@lists.re-wrenches.org>] On Behalf Of
Joel Davidson
Sent: Tuesday, November 17, 2009 4:56 PM
To: RE-wrenches
Subject: [RE-wrenches] SWR2500U Inverter
 Wrenches,
 Our customer has 24 each Kyocera KC130 modules and wants to go
grid-tied.
Can he use an SMA SWR2500U inverter with the fan kit? Is there a
better
inverter that will use all of his modules? If you have an
SWR2500U or a
better inverter option for sale, please contact me off-list.
Thank you very
much.
 Joel Davidson
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Re: [RE-wrenches] SWR2500U Inverter

[Dave Click]

It's of course your call as to what factors to use, and you can go as 
conservative as you want. When the sun hits the array and kicks the VOC 
up, it's also going to be warming the modules, which will of course 
knock the VOC back down. At 200 W/m2 you'll have about 90% of your VOC, 
which will turn the inverter on and move the array to its VMP. I could 
see the array topping 600VDC if it's a record cold temperature in the 
middle of the day, and the power goes out at noon, and the array is 
angled steeply enough to see >600 W/m2 and get its VOC up, and you have 
30 mph wind gusts keeping the array relatively close to ambient 
temperature. And it would need to be a newer array; a new array with a 
600V VOC would be expected to lose at least 2-3V from that every year, 
right?


That's why I feel confident using the ASHRAE numbers.

DKC

 Original Message 
Subject: Re: [RE-wrenches] SWR2500U Inverter
From: Kirpal Khalsa 
To: RE-wrenches 
Date: 2009/11/18 11:33

Solar Friends..as you have referenced Dave the code does allow 
for using the softer records relating to low temps..However.as 
in the example presented in the SMA 2500U discussion going on right now 
one string brings you pretty close to 600V at 14 degrees..Should you 
get a lower temperature and exceed the 600V you could damage the 
inverter.Its not that it will just not turn on...it will actually 
damage it and most inverter manufacturers will not honor a warranty if 
you exceed the voltage rating of their inverter..they also have very 
precise sensors to determine if the maximum voltage was exceededeven 
by just a small amount.
Typically when referencing temperature data I think it prudent to use 
the record low but have a more flexible position on the record 
highs.it is actually common for string sizing calculators to use the 
average high in string size calculationthe difference is that in the 
high temperature you dont risk damaging equipment.simply it may not 
operate during the high temperature...
My conservative me typically uses both record low and record high as my 
temperature parameters as this will both protect the system and allow 
the design to operate under any expected temps.That saidrecords 
were made to be broken!

Cheers,

--
Sunny Regards,
Kirpal Khalsa
NABCEP Certified Solar PV Installer
Renewable Energy Systems
www.oregonsolarworks.com <http://www.oregonsolarworks.com/>
541-218-0201 m
541-592-3958 o
 

On Wed, Nov 18, 2009 at 8:14 AM, Dave Click <mailto:davecl...@fsec.ucf.edu>> wrote:


Good catch Bob, there seems to be a page missing from that table...
this report from Bill's site has the complete table (at the end of
the file, again).

http://www.brooksolar.com/files/Expedited_Explanation-5-6-09.pdf


DKC

 Original Message 
Subject: Re: [RE-wrenches] SWR2500U Inverter
From: robert ellison mailto:reelli...@gmail.com>>
To: RE-wrenches mailto:re-wrenches@lists.re-wrenches.org>>
Date: 2009/11/18 11:01

My eyes must be bad, i just looked at the entire list 3 times
and New York state is not on it anywhere.
 I have see 48 below and just wanted to see what the averages
ctually were.
 Bob

On Wed, Nov 18, 2009 at 7:30 AM, Dave Click
mailto:davecl...@fsec.ucf.edu>
<mailto:davecl...@fsec.ucf.edu <mailto:davecl...@fsec.ucf.edu>>>
wrote:

   Just a note here- rather than using the record lows, you can
go back
   to the future and use the ASHRAE minimum expected temperatures as
   the 2011 NEC will allow explicitly. In the '08, it says to
use the
   "lowest expected ambient temperature," for which the ASHRAE
   temperatures are more appropriate than record lows. These ASHRAE
   temps will be higher than the record lows and will add a
little more
   cushion there at 600 VDC.

   So where to get these temperatures? Starting on page 47:
   http://www.solarabcs.org/permitting/Expermitprocess.pdf

   Also, in case you didn't know, www.pvselect.com
<http://www.pvselect.com>
   <http://www.pvselect.com/> is another option for string
sizing that

   features multiple inverters and a 1 degree temperature step
rather
   than the 9 degree (F) temperature step on the SMA sizer. They
have
   the Kyocera KD130 in their database, but not the KC130.

   DKC


    Original Message 
   Subject: Re: [RE-wrenches] SWR2500U Inverter
   From: Brian Teitelbaum mailto:bteitelb...@aeesolar.com>
   <mailto:bteitelb...@aeesolar.com
<mailto:bteitelb...@aeesolar.com>>>
   To: RE-wrenches mailto:re-wrench

[RE-wrenches] wiring the Soladeck

[Dave Click]

Wrenches-

How are folks wiring the Soladeck boxes? It seems that the intent is to 
use cord grips in the south end of the box, but I just saw another 
installation where the wires just came directly in through the space at 
the south end. Seems like the foam is included to keep bugs out rather 
than provide strain relief to those incoming conductors, so I guess I'm 
just looking for a reality check here.


Thanks and happy Thanksgiving!
DKC
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Re: [RE-wrenches] wiring the Soladeck

[Dave Click]

Thanks for the replies everyone- I appreciate the reality check.

I sent William some pictures for his Rogues' Gallery, so you can also 
see their green wires used for the ungrounded conductors. I didn't send 
the picture of the FMC (that's right, not liquid-tight) running down the 
exterior wall to the inverter, but probably should have.


Just saw that Heyco announced a new product that they also claim is UV 
resistant nylon; they don't call out their other cordgrips as UV 
resistant, though they're also nylon... but hopefully these truly are UV 
resistant since they're designed for combiner boxes.

http://www.heyco.com/products/sec_02/pdf/2-32.pdf

Thanks all!

 Original Message 
Subject: Re: [RE-wrenches] wiring the Soladeck
From: Scott Knapp 
To: re-wrenches@lists.re-wrenches.org
Date: 2009/11/24 22:16


Dave,

As you've seen on our installs we always use one or more strain reliefs 
in the south end of the box.  Including for the grounding conductor.  We 
use the nylon ones from Sealcon.  There is no way that the foam block 
and lid provide adequate strain relief.


http://www.sealconusa.com/productselection-ny.htm

Scott.

Scott M. Knapp, Ph.D.
Solartek LLC
Phone: 407-462-1182
Email: sc...@solartek.com
Web: www.solartek.com


On Tue, Nov 24, 2009 at 3:12 PM, Dave Click  wrote:


Wrenches-

How are folks wiring the Soladeck boxes? It seems that the intent is 
to use
cord grips in the south end of the box, but I just saw another 
installation

where the wires just came directly in through the space at the south end.
Seems like the foam is included to keep bugs out rather than provide 
strain

relief to those incoming conductors, so I guess I'm just looking for a
reality check here.

Thanks and happy Thanksgiving!
DKC





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Re: [RE-wrenches] NABCEP - grid tie---Off grid

[Dave Click]

> Speaking of IBEW, how
> about the installation done in Dorchester, Ma., do you mount your arrays
> vertically?

That (relatively small--5.4kW) array was installed vertically to improve 
its visibility from I-93. It was understood that vertical PV facing 
somewhat SE wouldn't have been as efficient as a 30 degree slope facing 
south, but visibility was more important than increasing the energy 
production by $60/yr.


DKC

 Original Message 
Subject: Re: [RE-wrenches] NABCEP - grid tie---Off grid
From: Tump 
To: 'RE-wrenches' 
Date: 2009/11/26 10:03

Having worked for many years educating my clients, legislators and other 
officials of the value of a NABCEP certification,NABCEP IS important to 
me. I have invested many hours working w/ the early supporters, 
developing  a national certification program which morphed into the 
NABCEP program. I also work on various NABCEP committees working to 
insure NABCEP,the test & the test questions are relevant AND continue to 
address the real world of PV installations I personally find your lack 
of support for the NABCEP certification undermining.
Recently while developing new test questions for /_both on & off grid 
applications_/, myself & the installers working w/ NABCEP, the testing 
lab & some other HIGHLY qualified individuals got into a row about how 
tough we were making the entry level questions. "This isn't what those 
kids will know". The installers argued that NABCEP is the best 
benchmark & the test was a method of helping our industry weed out those 
people that want a easy transition into our/your solar world. We were 
finally able to convince the dissenters that the tough questions WERE 
the right way to go.
I think that many folks see the NABCEP program "a way in",the actual 
certification test is NOT an easy.
It is true that NOTHING will prevent some low balling jerk (NABCEP 
certified or not) from getting the job.
There are those of us who see the value in the certification, while the 
St. of Maine sees it (the NABCEP test) as too tough a test so what did 
they do? They have developed  one of their own tests,something that 
allows very poor quality of work to be accepted for rebate funds, (some 
of it performed by IBEW & licensed electricians). Speaking of IBEW, how 
about the installation done in Dorchester, Ma., do you mount your arrays 
vertically?
 Yeah I loose jobs too, because I charge a competitive rate,install a 
quality a product,value my insurance, both health & liability.I 
also value my reputation as someone that is considered "one of the 
better installers" in the state where I live & work!
There are many of us that have worked to improve the value of the 
NABCEP program, you may have seen my personal attack & praise of the 
NABCEP program.
I find presently that the increasing awareness of the NABCEP program 
comforting,BUT, I too find the lack of support from the industry & some 
States frustrating.
Certification is NOT for everyone, its expensive & time consuming but w/ 
continued interest from folks that may be on the fence & the continuing 
hard work marketing the certification program "as the one to have", we 
will continue to see the quality minded customer looking for that NABCEP 
certification.
Please review some of the questions on the test, perhaps one of these 
days you too will see the value of NABCEP & become one of the proud, 
frustrated NABCEP certificate holders.
Were you also someone that said that computers were too costly and a 
waste of time?

OK I've gotta go & saddle bend up my horse & ride off to turkey land...
 
*t...@swnl.net* _*www.SWNL.net* 
_
   Solarwinds Northernlights  
*/   Serving Mid Coast Maine & Northern California

 Me.# 207-832-7574  Cl.#  610-517-8401/*
 
/*  Blair "TUMP" May*/

*/    MAINE'S CHARTER 
  _  NABCEP"Certified PV Installer"_/**/_
_  
    MAINE'S CHARTER 

   /**/_Trace Xantrex "Certified" Dealer / Installer"
_   /*
*/  /*

-Original Message-
*From:* re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of
*William Miller
*Sent:* Wednesday, November 25, 2009 2:48 AM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] Nabcep - grid tie---Off grid

Friends:

I'd like to make two brief points on the training/NABCEP debate:

1. If I thought NABCEP certification would get me one more job I'd
normally lose to a low-ball bidder, I'd be inclined to sit for the
test, but it won't.

2. Most solar electric installers could not be considered
electricians.  Until they learn the trade, they are not qualified to
install the most basic grid tie system.  Conversely, many
electricians with the most basic electrical skills think they know
all that needs to be known to design and install solar-electric. 
Wrong again.

Re: [RE-wrenches] High end Lawn Art was: NABCEP - grid tie---Off grid

[Dave Click]

I disagree, but maybe I'm just a sucker for BIPV since it's on my house. 
A lot of BIPV work- integrating into skylights, facades, or tile- could 
be interpreted as being "not a good renewable application," due to 
higher operating temperature or imperfect orientation.


Obviously, when looking at a prospective installation you should do the 
best with what you have and if you have a choice between two array 
locations, then with all else being equal you should install the array 
where it operates the most efficiently.


I think the key is just to make sure the customer is aware of the 
inefficiency that accompanies an installation like this. We're going to 
see a lot more BIPV in the future, and often we'll be locked in to the 
original geometries of the buildings; the aesthetics of 
awkwardly-oriented BIPV will likely win out over a high-profile racking 
system that keeps the system at optimal efficiency. There will still be 
jobs to turn down (e.g. an architect wants a building's white facade to 
be the backs of modules, while insisting on a 10-year payback).


DKC

 Original Message 
Subject: [RE-wrenches] High end Lawn Art was: NABCEP - grid tie---Off grid
From: Bill Loesch 
To: RE-wrenches 
Date: 2009/11/30 09:09


Hi Dave,

Isn't using the building face or other appendage, rather than or in addition
to the roof what one definition of BIPV is ?

Regarding the non optimum azimuth orientation -

Unfortunate that others around the country are seeing poorly implemented
renewable applications, too. IMHO, this is terribly counter productive in
that a highly visible system gives the message to the viewers that this is a
valid application. Perhaps it is a cost effective _marketing tool_, but
_not_ a good renewable application. It unfortunately promotes the general
public's misunderstanding of what a good installation is. Moreover, this
nonsense is often implemented by users that are promoting their technical
expertise (obviously in areas other than solar, hopefully).

The up side to this travesty of resources, materials, and labor is that the
solar array is less obviously, not performing well as compared to a wind
machine sitting idle.

I believe it was Red Adair (the world class oil field fire fighter) who is
given credit for the expression, "Don't be afraid to walk away." A sentiment
that might find use here.

I am aware of others on this List that have a web "Rogue's Gallery" of how
not to do it. Is there any place where this is a unified collection?

Respectfully,

Bill Loesch
Solar 1 - Saint Louis Solar



- Original Message - 
From: "Dave Click" 

To: "RE-wrenches" 
Sent: Monday, November 30, 2009 6:44 AM
Subject: Re: [RE-wrenches] NABCEP - grid tie---Off grid



Speaking of IBEW, how

 > about the installation done in Dorchester, Ma., do you mount your

arrays

 > vertically?

That (relatively small--5.4kW) array was installed vertically to improve
its visibility from I-93. It was understood that vertical PV facing
somewhat SE wouldn't have been as efficient as a 30 degree slope facing
south, but visibility was more important than increasing the energy
production by $60/yr.

DKC

 Original Message 
Subject: Re: [RE-wrenches] NABCEP - grid tie---Off grid
From: Tump 
To: 'RE-wrenches' 
Date: 2009/11/26 10:03


Having worked for many years educating my clients, legislators and other
officials of the value of a NABCEP certification,NABCEP IS important to
me. I have invested many hours working w/ the early supporters,
developing  a national certification program which morphed into the
NABCEP program. I also work on various NABCEP committees working to
insure NABCEP,the test & the test questions are relevant AND continue to
address the real world of PV installations I personally find your lack
of support for the NABCEP certification undermining.
Recently while developing new test questions for /_both on & off grid
applications_/, myself & the installers working w/ NABCEP, the testing
lab & some other HIGHLY qualified individuals got into a row about how
tough we were making the entry level questions. "This isn't what those
kids will know". The installers argued that NABCEP is the best
benchmark & the test was a method of helping our industry weed out those
people that want a easy transition into our/your solar world. We were
finally able to convince the dissenters that the tough questions WERE
the right way to go.
I think that many folks see the NABCEP program "a way in",the actual
certification test is NOT an easy.
It is true that NOTHING will prevent some low balling jerk (NABCEP
certified or not) from getting the job.
There are those of us who see the value in the certification, while the
St. of Maine sees it (the NABCEP test) as too tough a test so what did
they do? They have developed  one of their ow

Re: [RE-wrenches] 690.32(E) + MC?

[Dave Click]

I believe that in a Code Corner back in the '05 era, John Wiles had said 
that MC cable was OK to use, then in a later Code Corner he says that it 
isn't; I thought it was because part of the reason for a metal raceway 
is physical protection, and EMT/FMC would be sturdier than MC. But then 
I looked at the 2011 Code, which (as it currently stands) will allow MC:


(E) Direct-Current Photovoltaic Source and Output Circuits Inside a 
Building. Where dc photovoltaic source or output circuits from a 
building-integrated or other photovoltaic system are run inside a 
building or structure, they shall be contained in metal raceways, Type 
MC metal clad cable that complies with 250.118(10), or metal enclosures, 
from the point of penetration of the surface of the building or 
structure to the first readily accessible disconnecting means. The 
disconnecting means shall comply with 690.14(A), (B), and (D). [ROP 4-228]


The new 690.31(E) is about ten times longer than the '08 edition, now 
requiring the conduit to be >10" below the surface of the roof (to avoid 
firefighting equipment venting the roof) and labeling along that conduit 
too:

http://www.solarabcs.com/index.php?option=com_docman&task=doc_download&gid=248&&Itemid=72

And to save you a lookup:
250.118 Types of Equipment Grounding Conductors.
The equipment grounding conductor run with or enclosing the circuit 
conductors shall be one or more or a combination of the following:

...
(10) 	Type MC cable where listed and identified for grounding in 
accordance with the following:
a. 	The combined metallic sheath and grounding conductor of interlocked 
metal tape–type MC cable
b. 	The metallic sheath or the combined metallic sheath and grounding 
conductors of the smooth or corrugated tube-type MC cable


 Original Message 
Subject: Re: [RE-wrenches] 690.32(E) + MC?
From: R Ray Walters 
To: RE-wrenches 
Date: 2009/12/5 03:28


I think the issue here is 690.32 deals just with 'fittings and
connectors', not the actual wire or cable. I believe you meant to
reference 690.31 which says 'all raceway and cable wiring methods
included in this codeshall be permitted'. But you still have to
comply with 690.31E which says it needs to be in 'metal raceways or
metal enclosures' once it enters the building up to the first readily
accessible disconnect. Looking at article 100, the definition of
raceway does include flexible metal conduit, so it seems you could
use metal flex conduit and pull wire, but I know many inspectors
still won't allow it. Reading up in articles 320 and 330 for AC and
MC cables, MC doesn't say it's conduit, so it would be out, but AC
says its enclosed in a 'flexible metallic enclosure'. So now the
question is: Is metallic the same as metal? (Oh Boy are we splitting
semantic hairs now...). Bill or William are the ones to clarify
better than I on all of this, though. They've been involved in the
actual writing of the code. IMHO, it seems yet another point to be
clarified in future additions of the code. Meanwhile to be safe, most
of us are just running EMT once we penetrate the building. (which
opens yet another question: when have you penetrated the building?
above or below the roof flashing?)

I think I've caused enough trouble for now,

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




On Dec 4, 2009, at 7:47 PM, Darryl Thayer wrote:


I have always read metal conduit, The reason being the solar is
unfused source circuits, and there is no way for overcurrent
protective devices to open.  Therefore, the conductors must be
protected from starting a fire under conditions of continuous
overcurrent. darryl


--- On Fri, 12/4/09, d...@foxfire-energy.com
 wrote:


From: d...@foxfire-energy.com  Subject:
[RE-wrenches] 690.32(E) + MC? To: "RE-wrenches"
 Date: Friday, December 4,
2009, 5:18 PM I did a project a while ago for a supplier /
Installing out fit (who has their in house engineering types),
who told me that either MC or maybe AC cable did comply with
690.32E. today I'm being told that's not the case, and I can't
seem to put my finger on it ... any pointers? thanks db


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






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Re: [RE-wrenches] wind load

[Dave Click]

Something that may help with the inspector would be to alternate 
trusses. If your array spanned ten trusses, which I'll call A-J, and you 
have three rows of six rails:


Rail #1, 3, 5: attach to A, C, E, G, I, J
Rail #2, 4, 6: attach to A, B, D, F, H, J

It's not helping his concern on the end trusses but it would help with 
the interior trusses, anyway.


The SolarABCs.org expedited permitting report may help with things as 
well. Since these are engineered trusses that you're attaching to, I'm 
surprised that the inspector is giving you such grief!


We Florida guys love hearing about wind loading concerns in a 90mph 
zone! I work in a 130mph wind zone...


DKC

 Original Message 
Subject: Re: [RE-wrenches] wind load
From: Kent Osterberg 
To: RE-wrenches 
Date: 2009/12/5 11:45


Rebecca,

With three rows and six lags in every other rafter there is a tremendous 
force on each of the rafters.  Unirac has excellent information in their 
installation manual  that shows all 
the engineering info needed for ASCE-7, which is meets the  requirements 
for most building departments.  If you go through the calculations, you 
can determine the maximum force or load on each lag bolt.  And you 
should go through the calculations to make sure that the spacing and lag 
bolt penetration is adequate.  The adequacy of the roof structure is a 
question for the structural engineer.  Modern truss structures will 
handle it, and presumably that's what your structural engineer looked 
into.  At this point, I agree with William: it is time to go over the 
inspector's head with the argument that he doesn't have the authority to 
question the engineering.


Kent Osterberg
Blue Mountain Solar



Rebecca Lundberg wrote:

Hi William,

Thanks for responding. We have three long rows of modules, with rails 
attached every other rafter, every 4'. The inspector's argument is 
that two attachments for one row might be fine, but that the wind load 
for the entire array theoretically could be born by one rafter, and 
therefore it would pull the rafter right out of the house. This is 
only my year 3 as an installer, and while I'm not afraid to push the 
inspector if needed, I admit I want to be sure he isn't right, even 
though an engineer says so (because I'm not an engineer :-). So in 
your experience, is there a limit to an array size that would be 
'safe' for a home if the array is within the edges of the roof and 
flush-mounted? I feel like that's the real argument, you might safely 
attach one module, but he is saying when you multiply the modules you 
multiply the wind load to the house by the same factor.


Rebecca


Message: 3
Date: Fri, 04 Dec 2009 22:21:43 -0800
From: William Miller mailto:will...@millersolar.com>>
To: RE-wrenches mailto:re-wrenches@lists.re-wrenches.org>>
Subject: Re: [RE-wrenches] PV wind load
Message-ID: <6.0.1.1.2.20091204220550.061cd...@millersolar.com
>
Content-Type: text/plain; charset="us-ascii"; Format="flowed"

Rebecca:

It sounds like you have made an air-tight case (pun intended) and
you have
still not been able to convince this thick-headed inspector.  I
have had a
similar experience last summer that might be relevant:  After
being pushed
around beyond my patience, I fought back.  I worked up the chain of
command, stayed professional and put it all in writing.

I won the battle and set a precedent.  I have forbidden the building
department from assigning the problem inspector to my projects
and, to my
amazement,  the department obeys my request!

Good luck, and let us know how it turns out

William Miller



At 05:55 PM 12/4/2009, you wrote:
>Solar is somewhat 'new technology' where I live. :-) I have a
building
>inspector that feels that (32) Sanyo modules (6.88 kW array)
mounted to a
>house roof is going to cause undue stress to the roof truss (it is a
>regular house in a Minnesota suburb, building height is 26', 30
degree
>roof angle, in a suburban neighborhood. 2" x 4" manufactured
truss). We
>are leaving 12-24" on each edge with no PV, and are careful to
attach to
>the center of each rafter.
>
>The inspector is not that concerned with dead load, but is especially
>concerned with wind load. We have provided an engineering letter that
>ascertains that a solar array mounted parallel to the roof
surface is well
>within the parameters of what a typical roof truss can handle. We
were
>required to have an engineer look at this address specifically,
so we then
>provided an additional engineer's letter that affirmed that yes,
solar
>mounted in the manner we proposed (with Quick-Mount attachment
and Unirac
>SolarMount rails, all installed according to manufacturers'
instructions)
>would be fi

Re: [RE-wrenches] Fwd: Solar Panels for 98 Cents Per Watt

[Dave Click]

In Photon's side-by-side module test a few years ago, I remember that 
one of the worst-performing modules (in kWh/kW) had marketing materials 
that targeted the off-grid market. The author suggested that by 
targeting off-grid, they were able to obscure their low production- 
perhaps another reason why this email is targeting that market.


That being said, those 98c/W Kanekas look interesting...

 Original Message 
Subject: Re: [RE-wrenches] Fwd: Solar Panels for 98 Cents Per Watt
From: wind...@wind-sun.com 
To: RE-wrenches 
Date: 2009/12/10 12:21

That 98c/w is for those Kaneka high voltage thin film panels. Not a bad 
price per watt, but they are pretty inneficient - around 7% - so they 
take up twice as much space for the same watts.


The blems that I saw were also more than just "spotting".

.. 


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

- Original Message - From: "Howie Michaelson" 


To: 
Sent: Thursday, December 10, 2009 7:02 AM
Subject: [RE-wrenches] Fwd: Solar Panels for 98 Cents Per Watt


Hi all,

The message below was received by a friend of mine who has done all his
own installation work, including being an early adopter of the FIT program
while living in Germany many years ago.  He is wondering if this is a good
deal for his off-grid system.

What thoughts are there about the points made in this pitch?  This is the
type of marketing that more and more of my clients are seeing.

Has anyone had any traffic with Sun Electronics that they care to relate?

And, I thought at least the Evergreen blemishes were about minorly
misaligned cells, not spots.

Thanks,
Howie

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Re: [RE-wrenches] Best angle - direct grid tie

[Dave Click]

0.9 x latitude seems to be a good rule of thumb for direct grid-tie systems.

 Original Message 
Subject: Re: Malabar Cove  Solar Array
From: ScottT 
To: Dave Click 
Date: 2010/1/2 12:39


Hello Wrenches,

My Solar Pathfinder Assistant (SPA) claims that the optimum tilt angle
for the solar modules is latitude. I'm skeptical. The system being
designed is a direct grid tie, ground mount.

It seems to me that an angle of latitude will give a balanced angle for
both summer and winter charging. Since there is far less energy
available in the winter, is this balance really the best. Also, a
flatter angle in the summer should gain more hours of sun, since the sun
goes N of the E-W axis.

With ballasted systems, the 15 degree angle is supposed to work just
fine, due to better summer charging. Does anyone have an answer to what
really is the optimum tilt angle for a direct grid tie system? Is the
SPA geared toward off grid systems, or is latitude really the best?

Thank you and best wishes for the New Year,

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] Solar accumulation panel

[Dave Click]

There's no problem with installing the panel and 690.64(B) is the 
appropriate section to look at.


"690.64(B)(2) Bus or Conductor Rating. The sum of the ampere ratings of 
overcurrent devices in circuits supplying power to a busbar or conductor 
shall not exceed 120 percent of the rating of the busbar or conductor."


If you size the panel so that it can accommodate the sum of the 
inverters AND the utility side fuse/breaker, then this meets 
690.64(B)(2) no problem. For example, if you have 2 30A inverter 
breakers and 1 60A fused disconnect as your line side tap, that's 
30+30+60A total source that can energize the panel, so a 100A panel 
would work here as long as you follow 690.64(B)(7) and have the PV 
breakers at the opposite end of the main lugs/breaker.


If what you're trying to do is get away with a 60A panel rather than a 
100A panel, that's where you have to get special permission from the 
AHJ, and they'd probably require language somewhere along the lines of 
"PV circuits only. Do not add load breakers." This system would be safe 
if no loads are attached (you can easily see that you wouldn't see more 
than 60A flowing across the buses here), but the key is to affix a 
permanent label so that no additional breakers are ever added- just in 
case the next person along assumes that everything is NEC compliant.


DKC


 Original Message 
Subject: [RE-wrenches] Solar accumulation panel
From: Andrew Truitt 
To: RE-wrenches 
Date: 2010/1/12 13:57



Team wrenches - I feel like I've seen a provision in the Code for
installing a sub-panel to aggregate PV inverter outputs for the purpose
of simplifying the actual grid connection (such as for a line-side tap)
but I can't find it in 690.  I also seem to remember specific verbiage
that needs to be on the panel along the lines of "PV circuits only.  Do
not add load breakers." to ensure compliance with 690.64(B).  Does
anyone know where I can find this info in the NEC?


Andrew Truitt
Standard Solar Inc.


--
"Don't get me wrong: I love nuclear energy! It's just that I prefer
fusion to fission. And it just so happens that there's an enormous
fusion reactor safely banked a few million miles from us. It delivers
more than we could ever use in just about 8 minutes. And it's wireless!"

~William McDonough



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Re: [RE-wrenches] Supply Side Interconnections - Maximum Backfeed

[Dave Click]

Sometimes utilities will set a max too- here in Florida the 
investor-owned utilities have a rule that you take (d...@stc) x 0.85 to 
get the "AC equivalent" size of the array. That size then can't exceed 
90% of the service rating. Not sure if this is an issue in other states.


Scott McCalmont wrote:

Going all the way up to the rating of the service might not be such a
good idea. The utility may use smaller wires for the service drop than
you would expect based on the ampacity tables in the NEC. Considering
the example of a 400 A service:

- PG&E (local utility) requires 350 kcmil Aluminum conductors.
- Table 310.17 rates 350 kcmil Aluminum for 395 amps before temperature
correction.

With load diversity the smaller wires will be fine, but the output of a
PV system is continuous. Running the output of a system sized at 400
amps through the wires on a hot summer day could overload them.

So... it depends.

Scott

Scott McCalmont, P.E.
McCalmont Engineering
San Jose, CA
(408) 204-0318


On Thu, Mar 4, 2010 at 3:02 PM, Michael Kelly mailto:m...@solarflair.com>> wrote:

Kirpal,

That was always my interpretation as well.  So in the case of a 400A
service, I can backfeed 400A when utilizing a supply side
connection.  Others have thoughts on this?
- Mike

--
Michael Kelly
Project Manager / Project Engineer
NABCEP Certified Solar PV Installer ™

SolarFlair Energy, Inc.
11 Mayhew Street
Framingham, MA 01702
Direct Mobile: 617-899-9840
Main Phone: 508-293-4293
Main Fax: 508-293-4003
m...@solarflair.com 


On Thu, Mar 4, 2010 at 4:16 PM, Kirpal Khalsa mailto:solarwo...@gmail.com>> wrote:

Mike.i may be wrongbut I think i am rightyou are
limited by the wire size feeding the supply and/or  the
transformer size which supplies the service.depending on the
physical location of the tap you may be limited by the enclosure
and the enclosure ratings as well
would love to hear any other ideas...
Cheers,
--
Sunny Regards,
Kirpal Khalsa

NABCEP Certified Solar PV Installer
Renewable Energy Systems
www.oregonsolarworks.com 
541-218-0201 m
541-592-3958 o


On Thu, Mar 4, 2010 at 12:50 PM, Michael Kelly
mailto:m...@solarflair.com>> wrote:

Hi All,
Next to grounding, I find the calculation of the maximum
amount of backfeed current allowed in a supply side
connection to be the most vague issue in Article 690.  Let's
assume we have a 400A, 480/277 service in a commercial
building, a 400A main service disconnect, and the
jurisdiction is under NEC 2008.  What is the maximum
backfeed current allowed in a supply side connection?  The
only place the code points you to is 230.82(6), which is no
help, or to Article 705, which is no help either.  I know
that in the draft version of NEC 2011, there is
an expansion of 705.12(A) which states "* *Supply Side. An
electric power production source shall be permitted to be
connected to the supply side of the service disconnecting
means as permitted in 230.82(6). The sum of the ratings of
all overcurrent devices connected to power production
sources shall not exceed the rating of the service."  That
is a helpful sentence from the Code, but as it is in draft
form, what do we do under NEC 2008?  What have you used as a
maximum backfeed current for supply side connections?
Thanks,
Mike
--
Michael Kelly
Project Manager / Project Engineer
NABCEP Certified Solar PV Installer ™

SolarFlair Energy, Inc.
11 Mayhew Street
Framingham, MA 01702
Direct Mobile: 617-899-9840
Main Phone: 508-293-4293
Main Fax: 508-293-4003
m...@solarflair.com 

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Re: [RE-wrenches] Load or Line Side was Solar accumulation panel

[Dave Click]

Late reply, but if anyone ever needs the code reference for William's 
method:

404.6 Position and Connection of Switches.
(C) Connection of Switches. Single-throw knife switches and switches 
with butt contacts shall be connected such that their blades are 
de-energized when the switch is in the open position.


Voila- PV to the load side.

 Original Message 
Subject: Re: [RE-wrenches] Load or Line Side was Solar accumulation  panel
From: William Miller 
To: RE-wrenches 
Date: 2010/1/13 22:51


Carl:

You are correct. I had the exact argument with an inspector. Here is
what I did to make a convincing argument: I opened the disconnect and
then reached in and touched the load side contacts (inverter side) with
my fingers. I turned to the inspector and said, "Now it's your turn to
touch the line side." Case closed.

William Miller


At 05:17 PM 1/13/2010, you wrote:

Wrenches,

I just had an AHJ require me to switch the load and line connections
on the fused AC disconnect which sits between the inverters (AC
Combiner panel) and the point of utility connection. The inverter
was connected on the LOAD side of the fused disconnect, and while the
AHJ agreed this was the safest configuration, (when the disco is OFF
the fuses are safe to remove) he insisted that the PV array should be
connected to the LINE side of the disconnect since it is supplying
power rather than acting as a LOAD. Any similar experience or
arguments I can make based on the NEC which might help change the
position of the AHJ next time round? I still believe our initial
installation represents the safest configuration.

Carl Adams
SunRock Solar, LLC
_



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Re: [RE-wrenches] PV excellent battery charger

[Dave Click]

Is the answer here (at least the one that NABCEP intends) just that the 
VMP of a "12V module" is higher than the voltage of a 12V battery? With 
the higher voltage it will charge the battery with its corresponding 
current based on the I-V curve. The objective reads "Explain why PV 
modules make excellent battery chargers based on their I-V characteristics."


> My understanding is that the voltage, in excess of battery voltage, from
> the array, represents energy that is dissipated as heat in the 
batteries.


Feel free to correct me- the battery would present a load to the module 
and then the module would be producing at some point on the I-V curve. 
There's no real "excess voltage" lost here; by dropping the operating 
voltage of the module you're just not producing your max power out of 
the module. The power's never produced- it's not that it's lost as heat 
anywhere.


I think we can agree that "excellent battery chargers" is a bit of an 
exaggeration unless it's "why PV systems with the magic that Ray 
mentioned** make excellent battery chargers."


**A) the 3 stage charging (compared to traditional single stage AC chargers)
B) Temperature compensation
C) PWM that helps pulse off sulfation
D) Slower charge rates let batteries charge more fully without damage 
from overheating.



 Original Message 
Subject: [RE-wrenches] PV excellent battery charger
From: drake.chamber...@redwoodalliance.org
To: re-wrenc...@webmail8.g.dreamhost.com, 
@webmail8.g.dreamhost.com

Date: 2010/3/24 21:04


Can anyone tell me why PV is considered an excellent battery charger? I
think it is, only after the addition of a MPPT charge control.  Otherwise,
the battery drags the PV voltage below Vmp.

One of the NABCEP objectives for the entry level class is to explain why
PV modules make excellent battery chargers and show this through the IV
curve.

Thank you,

Drake

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Re: [RE-wrenches] Supply Side Tap Overcurrent Protection

[Dave Click]

Looks like your question is answered but something else to look out for- 
this is pretty straight-forward for batteryless systems but for 
battery-backup and a line-side tie, you're adding a big load to the 
service conductors for battery charging and pass-through current to 
critical loads. If you're tying in your battery-backup system as a load 
side connection, if you have a high house load and a high 
battery-charging load then the main breaker trips to protect those 
service conductors. However, by bypassing the main here you could be 
pulling enough power in to overload them and cause a meter fault.


But at least when the meter fails you have your important stuff on 
battery-backup...


Dave Palumbo wrote:

Wrenches,

I am tasked with reviewing an installation by a licensed electrician in
Vermont and would like help with the following:

Grid-tied PV system with battery back-up. AC point of connection is a
supply side tap (done on customer side of utility meter ) then traveling
5 feet of #2 THHWN in 1” EMT to the 60 Amp 240vac Lockable Utility
Disconnect (unfused) and continuing 15 feet #2 THHWN 1” EMT to Xantrex
XW 60 Amp breaker.

I had said that the 60amp 240vac lockable disconnect needed to be fused,
and received the following reply from the installing electrician.//

/ /

/<< “The Xantrex XW Power Distribution Panel contains the required over
current protection (60 amp/

/double pole circuit breaker) negating the need for a redundant fuse at
the Utility Disconnect switch.” >>/

/ /

I am on a short trip in Florida and away from my code books. Can someone
provide guidance and code reference please? I am concerned about the 20
foot distance of the un-protected circuit from the supply side tap and
also the interrupt rating of the 60 Amp breaker in the Xantrex
distribution panel.

David Palumbo

Independent Power LLC

Offices in Lamoille and the Champlain Valley

802.888.7194

www.independentpowerllc.com



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Re: [RE-wrenches] Ground Mount PV DC Disconnects and 690.13

[Dave Click]

I'd agree that 690.13/14 don't require a DC disconnect out there 
(notably 690.14(C)(5)). I'd still think it's a good idea for maintenance 
and safety so that you don't need to go 300 feet to turn off power and 
worry about lockout/tagout.


You would have to wire the two outer poles in series to use the 361RB 
disconnect per its UL listing. Per Schneider Electric's "Self-Certified" 
method you'd be fine breaking it just once (the 30A disconnect can take 
a 12.8A Isc).



 Original Message 
Subject: Re: [RE-wrenches] Ground Mount PV DC Disconnects and 690.13
From: Dave Palumbo 
To: 'Wrench List' 
Date: 2010/3/30 10:43


Wrenches,

For a ground mounted PV array I do NOT see where 690.13, 690.14 mandates
a DC disconnect at the array itself. My question is what do you do as
“best practice” for safety, or for service of inverter disconnect. I
have been using 600VDC SQ-D disconnects at our ground mounts and I’m
wondering if it’s just plain overkill, or reasonable practice.

For example: 4kW Ground Mounted PV array with a Maximum Voltage of 567
DC. DC wire run (buried pvc conduit) of 150 feet to the inverter with
integral DC disconnect. Inverter is located on outside wall of the house
next to utility service.

Also. With this system, if I use a DC disco at the array, can I safely
use the SQ-D HU361RB 30 Amp 3 pole 600VDC disconnect. The system is one
string of 20 Evergreen 205’s, so 11.93Isc x 1.25 for a current of 14.94
Amps Max. By using 2 poles in series can we use this disconnect safely?

Dave

David Palumbo, NABCEP Certified PV Installer

Independent Power LLC

Offices in Lamoille and the Champlain Valley

802.888.7194

www.independentpowerllc.com



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Re: [RE-wrenches] Overcurrent Protection on a Subpanel

[Dave Click]

One could interpret that if you have 6 or more inverter breakers getting 
combined in a panel, you'd want one main breaker so that you wouldn't 
have to turn off all ten individually to disconnect the system. 
Something else to ask the AHJ.


Peter Parrish wrote:

When we use a sub-panel to combine the output of two or more inverters,
we buy the sub-panel without a main breaker. A wrench who is working
with us now, recommends buying sub-panels with the main breaker, which
increases cost by about 50%. Is this a code requirement? Does it depend
on the distance between the sub- and main panels?

- 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



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Re: [RE-wrenches] AC Coupled Issues

[Dave Click]

Jeff- The Sunny Boys can be reprogrammed into "off grid" mode so they 
can work between 56-64 Hz, but I believe you need both a service cable 
and a call to SMA tech support to make that happen. They then note in 
their system that that inverter's been adjusted to no longer meet UL 1741.


Jeff Yago wrote:

As mentioned before, many of our clients want battery backup with
their solar, but are not off-grid.  They also want a generator so
battery banks can be down-sized.   For many of these applications we
use a SunnyBoy at the array when the aray is located hundreds of feet
from house, and usually a Xantrex battery based inverter at the
house, and backfeed the solar inverter into the inverter's emergency
loads panel.  We pass this backfeed through a heavy duty relay
controlled to open on high battery voltage. Yes, SunnyBoy with
SunnyIsland is better match, but since one is 120 V and the other is
240V that means adding transformers or using two SunnyIslands.

Here is the issue - The SunnyBoy is working perfectly when grid power
is passing back to it through the backfeed connection.  However, when
this system operating off-grid when the grid is lost, the SunnyBoy
"sees" the fake grid power coming from the Xantrex which it shows on
L1 and L2 readings, but it is staying in the waiting mode and will
not connect.  No errors, just acts like grid a morning startup and
stays that way.   I have had problems before with Fronius doing this
and they have provided secret codes to open up the program settings
for the grid which solves the problem when grid power is poor quality
typical at end of line.  Is this solution possible with SunnyBoy
inverters, or is there something else going on.  Have not had this
problem on other AC coupled systems using the same combination of
inverters.

Thanks,

Jeff Yago

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Re: [RE-wrenches] PVWatts Module Temperature Coefficient (was Enphase derate)

[Dave Click]

It seems to be -0.5%/degC:
http://rredc.nrel.gov/solar/calculators/PVWATTS/moreabout.html


 Original Message 
Subject: [RE-wrenches] PVWatts Module Temperature Coefficient (was 
Enphase derate)

From: Joel  Davidson 
To: RE-wrenches 
Date: 2010/4/18 12:23


Wrenches,
PVWatts does not accurately predicate Unisolar and Sunpower module
performance because it uses a generic single crystal silicon solar
module power temperature coefficient (I think -0.4% per degree C). Does
someone have the technical paper that specifies PVWatts module
temperature coefficient? Thank you.
Joel Davidson

- Original Message -
*From:* Kirk Herander, VSE 
*To:* 'RE-wrenches' 
*Sent:* Sunday, April 18, 2010 4:32 AM
*Subject:* [RE-wrenches] Enphase derate (was Tilt biased)

Enphase has a tech note pdf for download that recommends and
rationalizes a PV watts derate of .819 instead of the standard .77
(which IMO is a little conservative to begin with).

http://www.enphaseenergy.com/downloads/EnphaseAppNote_PVWatts.pdf

Kirk Herander

Vermont Solar Engineering

802.863.1202 fax 802.863.7908

VT RE Incentive Program Partner

NYSERDA Incentive-eligible Partner

NABCEP^TM Certified Installer

*From:* re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] *On Behalf Of
*Allan Sindelar
*Sent:* Sunday, April 18, 2010 3:18 AM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] Tilt biased

Holt,
Feedback re the low tilt angle: Go for it, you're good.

Re wind loading: check out UniRac's Code Compliant Installation
Manual, http://www.unirac.com/pdf/ii227.pdf, especially pages 3-9.

Less wind loading is one of the main reasons for going with a lower
tilt angle. Another is closer module row spacing (at 3X height RoT)
without inter-row shading.

No experience with Enphase.
Allan

*Allan** Sindelar*
_alla...@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_ 



_hol...@sbcglobal.net_  wrote:

Searching for opinions.is this "over design"?

Designing small system (2.35kW). Customer uses gas for heating.
Typical A/C unit. I was thinking of biasing the tilt to summer
production for greater offset of summer demand (lat 31.6, proposing
18). No net metering in this part of the world. PVwatts shows a drop
of 2% /yr. in production , 5% higher production for A/C months.
Feedback?

Also, this array will go on a carport. I understand that windloading
is actually greater for an open structure than one with walls
(another reason for lower tilt) - is there any one that can direct
me to data on finding out how much more?

Lastly, what is a good avg. target derate factor for Enphase
inverters (real world)?

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] Volcanos, reduced solar production and kWh performance warranties

[Dave Click]

Something you can do is guarantee a kWh amount given a certain amount of 
irradiance. Offer X annual kWh given 2000 sun-hours, perhaps. If you're 
in a snowy area, just make sure the irradiance meter keeps snow on it as 
long as the modules would.


Of course you wouldn't just take 0.8 into PVWatts and make that your 
guarantee... a hot year could impact your production quite a bit so be 
sure to include a cushion. Other things can still bite you here, like 
the aforementioned example where there's a delay getting an inverter 
tech to a remote area.


 Original Message 
Subject: Re: [RE-wrenches] Volcanos, reduced solar production and kWh 
performance warranties

From: Max Balchowsky 
To: RE-wrenches 
Date: 2010/4/26 09:27


We've had a lot of people asking about "performance" warranties and I
stay very far away from any language that hints at a performance
guarantee. I think this especially important in the "PPA" I give them
all the product specifications, run the production charts and then
explain how little control I have over the things that affect output (to
the grid) which includes weather and the way they use electricity.

Max Balchowsky
SEE Systems
1048 Irvine Ave. Suite 217
Newport, Beach Ca. 92660
760-403-6810


*From:* Marco Mangelsdorf 
*To:* RE-wrenches 
*Sent:* Sun, April 25, 2010 8:02:58 PM
*Subject:* [RE-wrenches] Volcanos, reduced solar production and kWh
performance

This thread brings up a very timely issue that I’m dealing with right
now with PV Power Purchase Providers. As an integrator providing turnkey
PV systems of X kW, I’m being asked to contractually agree to a minimum
performance warranty for said PV systems. I am EXTREMELY uncomfortable
to any such clause in any contract that I would sign. I have strong
confidence in my PV design capabilities and engineering support and in
my professional crew to install a top-quality PV system. I have a lot
less confidence in an inverter manufacturer being able to get to a site
on a Hawaiian island in the middle of the Pacific in a super timely
fashion as the lost PV kWhs rack up. And as I mentioned in a previous
post today, we have an active volcano here that’s been spewing since
1983, a volcano that could get a lot worse on any given day. I’m leaning
strongly against agreeing to any such clause. Way too bad a precedent to
set. Way too much of a liability.

Anyone else had to deal with this bugger of a performance warranty demand?

Thanks,

marco

ProVision Solar

Marco:

Our production /schedule/ has been in tatters - lowered by perhaps 30%
because of the rain can't plan, can't do. Then I pay overtime on
good days to (try to) catch up.

We have a number of systems online and I had not thought to actually
review and compare from this year to last. I'll let ya know.

We'll get a call like - "My bill is higher than last year (edison has a
bar graph of monthly consumption for the past 13 months) and I'd like
you to look at my system" or My meter is not going backwards, should I
call edison?" The weather is so consistently wet this winter (think
Hilo) that we usually just need to ask-

"Been outside lately?"

But everywhere is so green and the desert bloom is outrageous.

http://www.desertusa.com/wildflo/ca.html

Pat Redgate

Ameco Solar

In a message dated 4/25/2010 12:24:53 P.M. Pacific Daylight Time,
ma...@pvthawaii.com writes:

Pat,

Kicked your butts as far as lower output? If so, by how much on a
percentage basis?

On the Big Island of Hawaii, we’ve had a very active volcano doing
its thing since 1983. With the normal trade winds, the vog (volcanic
smoke + fog) gets blown south past the volcano, around the south tip
of the island and */then back up/* along the west side of the
island. Which means that Kona-side residents can be in a yucky vog
zone for days and sometimes longer. Think L.A. on a smoggy summer
day. And as far as percentage decrease in solar output, I really
have little accurate clue.

Marco

ProVision Solar

Kicked out butts, in fact.

Pat Redgate

Ameco Solar

No virus found in this incoming message.
Checked by AVG - www.avg.com 
Version: 9.0.814 / Virus Database: 271.1.1/2833 - Release Date: 04/24/10
20:31:00



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Re: [RE-wrenches] Volcanos, reduced solar production and kWh performance warranties

[Dave Click]

Good call Ray to incorporate out-of-spec grid in areas where that's an 
issue (and probably a good idea to include just in case!).


If you need justification on future projects as to why you can't just 
guarantee a flat #:

http://rredc.nrel.gov/solar/calculators/PVWATTS/version1/interp.html

"For these variations and the uncertainties associated with the weather 
data and the model used to model the PV performance, future months and 
years may be encountered where the actual PV performance is less than or 
greater than the values shown in the table. *The variations may be as 
much as 40% for individual months and up to 20% for individual years.* 
Compared to long-term performance over many years, the values in the 
table are accurate to within 10% to 12%."


R Ray Walters wrote:

I think to make any energy production warranty fair, it would have to
include an on-site monitoring package that tracked cell temp,
insolation, and grid conditions. Then the installed system would be off
the hook if the grid was out of spec, insolation levels were low, cell
temp too high, etc. The performance warranty would be limited to the
actual site conditions.
I know its scary, but the one advantage I see of this type of warranty
is that it gives an edge to companies that do a better job, better
installation, and sell higher quality equipment.
It definitely would separate the wheat from the chaff. (or the Sunpower
from the Chinese poly)

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




On Apr 25, 2010, at 9:02 PM, Marco Mangelsdorf wrote:


This thread brings up a very timely issue that I’m dealing with right
now with PV Power Purchase Providers. As an integrator providing
turnkey PV systems of X kW, I’m being asked to contractually agree to
a minimum performance warranty for said PV systems. I am EXTREMELY
uncomfortable to any such clause in any contract that I would sign. I
have strong confidence in my PV design capabilities and engineering
support and in my professional crew to install a top-quality PV
system. I have a lot less confidence in an inverter manufacturer being
able to get to a site on a Hawaiian island in the middle of the
Pacific in a super timely fashion as the lost PV kWhs rack up. And as
I mentioned in a previous post today, we have an active volcano here
that’s been spewing since 1983, a volcano that could get a lot worse
on any given day. I’m leaning strongly against agreeing to any such
clause. Way too bad a precedent to set. Way too much of a liability.
Anyone else had to deal with this bugger of a performance warranty demand?
Thanks,
marco
ProVision Solar
Marco:
Our production /schedule/ has been in tatters - lowered by perhaps 30%
because of the rain can't plan, can't do. Then I pay overtime on
good days to (try to) catch up.
We have a number of systems online and I had not thought to actually
review and compare from this year to last. I'll let ya know.
We'll get a call like - "My bill is higher than last year (edison has
a bar graph of monthly consumption for the past 13 months) and I'd
like you to look at my system" or My meter is not going backwards,
should I call edison?" The weather is so consistently wet this winter
(think Hilo) that we usually just need to ask-
"Been outside lately?"
But everywhere is so green and the desert bloom is outrageous.
http://www.desertusa.com/wildflo/ca.html
Pat Redgate
Ameco Solar
In a message dated 4/25/2010 12:24:53 P.M. Pacific Daylight Time,
ma...@pvthawaii.com  writes:

Pat,
Kicked your butts as far as lower output? If so, by how much on a
percentage basis?
On the Big Island of Hawaii, we’ve had a very active volcano doing
its thing since 1983. With the normal trade winds, the vog
(volcanic smoke + fog) gets blown south past the volcano, around
the south tip of the island and */then back up/* along the west
side of the island. Which means that Kona-side residents can be in
a yucky vog zone for days and sometimes longer. Think L.A. on a
smoggy summer day. And as far as percentage decrease in solar
output, I really have little accurate clue.
Marco
ProVision Solar
Kicked out butts, in fact.
Pat Redgate
Ameco Solar

No virus found in this incoming message.
Checked by AVG - www.avg.com 
Version: 9.0.814 / Virus Database: 271.1.1/2833 - Release Date:
04/24/10 20:31:00

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Re: [RE-wrenches] FW: Enphase performance

[Dave Click]

I've got my SMA SB5 on a revenue grade meter and it's actually 
under-reported slightly since I started comparing it last August. SMA's 
counter has increased by 5649 kWh while the revenue meter has increased 
5666 kWh- only 0.3% off. If I remember correctly from their training 
session they said they're usually within 1%, but their tech documents 
say +/- 5%. YMMV.


 Original Message 
Subject: Re: [RE-wrenches] FW: Enphase performance
From: Kirpal Khalsa 
To: RE-wrenches 
Date: 2010/5/7 12:38


This same issue has come up over the years for us..first with PV
Powered inverters and then noticed in Fronius as well..We have
noticed in most of our grid tied systems that are connected thru a
"revenue grade meter" for Oregon Energy Trust production reporting, that
the inverter always has a higher performance than indicated on the
"utility grade meter".  We have seen the discrepency  as high as 10%.
Over time this adds up to significant kWh differences.  In our
experience the inverter always has the higher kWh reporting, we have
attributed this to the inverter wanting to report a good production
number, to boost their efficiency claims..maybe even more than is
accurate.I have asked PV Powered and Fronius about this and their
line is that to put a "revenue grade meter" into the inverter would be
cost prohibitive..interesting as the readily available revenue grade
meters are only $30-$60.   I would gladly pay that much extra if I
didn't have to wire in an additional meter.
I don't think this problem is unique to the Enphase units (i haven't
installed any of these), I think all inverters should be required to
install the revenue grade meters to give accurate reporting of actual
production.   Similar to how states have a "weights and scales" accuracy
certification, energy consumption and production meters should be
similarly calibratable.

--
Sunny Regards,
Kirpal Khalsa
NABCEP Certified Solar PV Installer
Renewable Energy Systems
www.oregonsolarworks.com 
541-218-0201 m
541-592-3958 o



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Re: [RE-wrenches] Enphase System Labeling

[Dave Click]

Quick poll- how many inspectors/utilities out there require the "live on 
both sides" label for AC Disconnects, even after you explain to them 
this only applies to DC disconnects? Even though it's inaccurate, I feel 
that it at least gives unqualified personnel pause before they open up a 
switch to something they don't understand.


DKC

Dana wrote:

This was our last batch

*Labeling For Grid-tie Solar Electric System*

*Great Solar Works, Inc., 970-626-5253*

* *

* KNOPP SIGNS ***

* *

*Qty – 2, Color red*

* *

*INTERACTIVE SYSTEM POINT OF INTERCONNECTION*

*Enphase Micro-Inverters [1] per module [17] Total*

* *

*PHOTOVOLTAIC SYSTEM SOURCE*

* *

* PV System Total Watts 3.910 KW*

* Maximum AC Output Operating Current 13.6 Amps*

* AC Operating Voltage 240 Volts *

* *

*For information and service contact: *

*Great Solar Works, Inc., 970-626-5253*

* *

*Qty – 1, Color red*

* *

*PHOTOVOLTAIC SYSTEM SOURCE*

* *

* PV System Total Watts 3.910 KW*

* Maximum AC Output Operating Current 13.6 Amps*

* AC Operating Voltage 240 Volts *

* *

*For information and service contact: *

*Great Solar Works, Inc., 970-626-5253*

* *

*Qty – 1, Color red*

* *

*PHOTOVOLTAIC AC SYSTEM UTILITY DISCONNECT*

*WARNING - ELECTRIC SHOCK HAZARD - DONOT TOUCH TERMINALS.*

*TERMINALS ON BOTH THE LINE AND LOAD SIDES MAY BE ENERGIZED*

*IN THE OPEN POSITION. IF A GROUND FAULT IS INDICATED THE NORMALLY
GROUNDED CONDUCTORS MAY BE ENERGIZED AND UNGROUNDED*

* *

*For information and service contact: *

*Great Solar Works, Inc., 970-626-5253*

* *

*Qty -1, Color Yellow*

* *

*PHOTOVOLTAIC SYSTEM CONNECTED*

*THE AC PV DISCONNECT IS LOCATED *

*Next to Meter on South Wall *

*For information and service contact: *

*Great Solar Works, Inc., 970-626-5253*

* *

Thanks, Dana Orzel

Great Solar Works, Inc

E - d...@solarwork.com

V - 970.626.5253

F - 970.626.4140

C - 970.209.4076

web - www.solarwork.com

Responsible Technologies for Responsible People since 1988"



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Re: [RE-wrenches] Oceanlink

[Dave Click]

I hope for your sake that you're kidding, because your residential 
customers may eventually find out that the power-save devices don't 
deliver the promised savings and will ask you why it was a $400 option.


I'm guessing that the Oceanlink "Energy Solution" is even less effective 
than the power-save units, based on the three nonfunctional company 
websites and the founder's previous job being a PhD in electrical 
engineering; no wait, I mean salesman.

http://forums.mikeholt.com/showthread.php?t=91211
http://www.mikeholt.com/newsletters.php?action=display&letterID=434

"Run away!!!"

Max Balchowsky wrote:

Does anyone have any experience with the Oceanlink Energy Solution power 
conditioners. They claim up to 35% energy savings on a
"normal " residential installation.
They are a little
more sophisticated that the power save units we have used in the
past

Max Balchowsky
Design Engineer
SEE Systems
1048 Irvine Ave Suite 217
Newport Beach, Ca. 92660
760-403-6810

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Re: [RE-wrenches] FSEC Approval Required for Permit?

[Dave Click]

Jason, I don't believe that you're working with correct information and 
I'm not sure who you spoke with here at FSEC. Please contact me offlist 
so we can discuss this further.


Also, we'd be pretty excited to learn that you were installing 200 
systems in the state. Carry on!


 Original Message 
Subject: [RE-wrenches] FSEC Approval Required for Permit?
From: Jason Szumlanski 
To: re-wrenches@lists.re-wrenches.org
Date: 2010/6/3 09:57


Hi Wrenches,

Has anyone dealt with a jurisdiction that requires FSEC or similar
system approval as a prerequisite for obtaining a PV permit? Although we
have installed many systems in a particular jurisdiction in our area,
they just rejected a permit application because we do not have an FSEC
system certification on this system (24 Enphase microinverters). We are
having a hard time getting them to explain from where the requirement
came. It seems like a nonsense roadblock to me. I can't imagine what
purpose an FSEC certification would serve in the case of microinverters.
As long as you are using a module on Enphase's compatibility list and
the module itself has FSEC certification, can you think of any logical
reason to jump through this hoop?

On that note, I contacted FSEC to see what it would require to certify
Enphase microinverter systems. They are telling me that we would have to
apply for one system, and then apply for "similar" systems if the number
of inverters changes. That doesn't make any sense to me. Are we supposed
to submit applications for 1, 2, 3...50...150 module systems? I doubt
they have time to deal with the paperwork for hundreds of similar system
applications. Imagine dropping 200 similar system applications in their
inbox to cover all quantities of microinverters.

Jason Szumlanski
Fafco Solar
Cape Coral, FL

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Re: [RE-wrenches] #10 THWN-2

[Dave Click]

THWN-2 smaller than #8 is hard to find but I hear 
http://www.encorewire.com/site_flash/index.html makes it and that 
Graybar sells it. When I asked Southwire about it about two years ago, I 
got a collective "huh?"


 Original Message 
Subject: Re: [RE-wrenches] #10 THWN-2
From: David Brearley 
To: RE-wrenches 
Date: 2010/7/22 21:33


Marco,

The #10 THWN wire that your local suppliers carry may be cross-listed as
THWN-2. My understanding is that it is not uncommon for smaller gauge
wire to carry more listings than are printed on its insulation. (If
that’s not true, we’ll find out shortly from someone on the list.) If
your local supplier can’t confirm this cross-listing for you, I’d try
tracing back to ask their supplier or the manufacturer.

David Brearley, Senior Technical Editor
/SolarPro/ magazine

On 7/23/10 12:52 AM, "Marco Mangelsdorf"  wrote:

Finding that wire in these here parts is pretty much impossible.

Can any of my CA. brethren/sistren provide me any leads on
wholesalers in either northern or southern CA. that carry #10 THWN-2
wire?

Thanks,
marco








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Re: [RE-wrenches] Tax credit question.

[Dave Click]

The obvious disclaimers of course apply to this message...

The only time a customer would find out that they were "disallowed" is 
if they are audited, right?


Anyway, from the 5695 form sent out earlier, emphasis added:
"Qualified solar electric property costs. Qualified solar electric 
property costs are costs for property that uses solar energy to generate 
electricity for use in your home located in the United States. No costs 
relating to a solar panel or other property installed as a roof (or 
portion thereof) will fail to qualify solely because the property 
constitutes a structural component of the structure on which it is 
installed. /*The home does not have to be your main home.*/"


"Main home" appears to be an issue only for fuel cell installations and 
Part II of the form (PV credit is in Part I).


Home is defined as "A home is where you lived in 2012 and can include a 
house, houseboat, mobile home, cooperative apartment, condominium, and a 
manufactured home that conforms to Federal Manufactured Home 
Construction and Safety Standards. 2012 Form 5695 "


It sounds like the house in Jesse's situation would qualify. A tree 
stand would not.


2012 Form 5695
On 2013/7/29 19:40, Larry Crutcher, Starlight Solar Power Systems wrote:
We install hundreds of RV power systems, as high as $18,000 cost, and 
tell all of our customers about the tax credit. Many have reported 
back that they were allowed the tax credit. No one has ever told me it 
was disallowed. Some customers are full time, some only use the RV 
occasionally.


Larry

On Jul 27, 2013, at 4:41 PM, Jesse Dahl > wrote:


So, has anyone had a customer install a ITC eligible system on a 
second "residence" and claim the credit?


Jesse



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Re: [RE-wrenches] Sunny Island question

[Dave Click]

Allan- SMA tech support confirmed with me yesterday that the 3/4/5 kW TL 
units are compatible with the SMA frequency shifting.


On 2013/8/2 16:34, Allan Sindelar wrote:

Will the Sunny Island mate up with these Sunny Boys that have the
limited backup capability during an outage, as they will with standard
Sunny Boys?
Thank you, Allan

--- Original Message 
Subject:Re: [RE-wrenches] SMA Secure Power Supply
Date:   Tue, 23 Jul 2013 23:16:23 -0600
From:   Orion Thornton 
Reply-To:   RE-wrenches 
To: 'RE-wrenches' 


Hi Carl and All,

This spring we had the opportunity to install a 5000-TLUS inverter for a
client, as a pre-release version.  The inverter was commissioned on April
1st and has produced about 2.7 MWhs thus far.  As mentioned, the secure
power supply (SPS) requires a dedicated outlet with a switch to control its
operation.   For this installation we installed the SPS in the mechanical
room, which is about 50 ft from where the inverter is located.  We chose the
mechanical room because it is centrally located within the floor plan of the
home, making it easily accessible to plug in emergency type loads, i.e. cell
phone chargers, laptops, lamps, etc.. It is also very close to the fridge,
which we plugged in with a short extension cord and tested its operation in
the "stand-alone" mode (which is what the inverter display when the grid is
down and the SPS in activated).  The inverter had no problem powering the
fridge.  The inverter display showed about 900 watts bypassed from the solar
array to the SPS when the fridge cycled onI must say it was a very cool
feeling seeing this happen.

As far as the inverter itself goes, I only have a few minor complaints.
Like the old SMA 1800U and 2500U, the conduit knockouts on the bottom of the
inverter are at a slight angle, which means you must put a slight bend in
your conduit.  This is obviously a bit annoying and I can only guess it has
something to do with the plug and play nature of non-U.S. installation
techniques.  The TLUS inverters are also lacking Bluetooth communication,
unlike their HFUS counterparts. I think this is a nice feature of the HFUS
inverters and wish it was integrated into the TL's.

With no real difference in cost compared to traditional grid-direct
inverters, I see no reason not to specify the TL, especially for someone who
has a desire for "limited" power supply during a grid outage.   They can
always add a Sunny Island later on, if a more robust backup system is
needed.

I hope this helps.

Orion Thornton
Onsite Energy
NABCEP Certified Solar PV Installer

-Original Message-
From:re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Jesse Dahl
Sent: Tuesday, July 23, 2013 4:11 PM
To:wire...@gmail.com; RE-wrenches
Subject: Re: [RE-wrenches] SMA Secure Power Supply

I know the MREA in WI has one installed on site, but not sure who installed
it.

Do they have a representative on the list?

Jesse

Sent from my iPhone

On Jul 22, 2013, at 6:18 PM,wire...@gmail.com  wrote:


If we have another long outage here in CT and we seem to have one every

year now, I don't want to have to explain to my customers why I didn't use
this inverter.

--

*Allan Sindelar*
_Allan@positiveenergysolar.com_ 
NABCEP Certified PV Installation Professional
NABCEP Certified Technical Sales Professional
New Mexico EE98J Journeyman Electrician
Founder and Chief Technology Officer
*Positive Energy, Inc.*, a Certified B Corporation^TM
3209 Richards Lane
Santa Fe, New Mexico 87507
*505 424-1112 office 780-2738 cell*
_www.positiveenergysolar.com_ 



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