Erika,
The most correct answer (which is a really funny thing to say) is to use
John Wiles' "5-step program"-that's what I call it. It is published in one
of the appendices of his latest "Suggested Practices" document. If you can
actually follow what he leads you through (that's why I call it t
Erika,
The most correct answer (which is a really funny thing to say) is to use
John Wiles' "5-step program"-that's what I call it. It is published in one
of the appendices of his latest "Suggested Practices" document. If you can
actually follow what he leads you through (that's why I call it t
Tom,
Your dc clamp-on meter would have saved you from removing a conductor that
had current on it. It is likely a lightning event caused the LA602 to do its
job-thus the cracked case. The dc clamp-on meter would have shown the
current flowing into the SOV and on to ground.
Bill.
From: r
Allan,
Square D makes 2-, 3-, and 4-pole models from 30 amps to 1200 amps that are
600Vdc rated. They have by far the most selection of any company at the
moment. The 200-Amp and up versions must pass through two poles of the same
switch. I'm using 3, 2-pole 600A units on 500 kW inverters at th
William,
In a series string, the one-cell shading in the long dimension will reduce
the voltage of the string by 1/3 of one module. This is often a small amount
of voltage since 12 or 13 modules are in string. In lower voltage systems,
the loss will be much more pronounced. No shading is good
Allan,
My beard is pretty gray these days, so I'll bite. Without getting deep into
exactly where these modules have degraded to, I think your idea of adding
the extra MSX77s is a good one, although it might be a little overkill.
Since the customer has them, I would use them.
The other issue
Matt,
They claim to use a bi-polar array with 600Vdc per pole. All bipolar arrays
must be grounded, so they must be grounded. They claim to be grounded
through the ac service transformer while operating. They are fundamentally
similar to many ungrounded designs. So, it IS grounded during operat
Peter,
The issue is the same as it was last year. The operating voltage of each
string will be nearly identical throughout the day if the strings are the
same length and not shaded. Put them on a single inverter.
The Fronius report was not discussing a special algorithm for dealing with
this situ
Peter,
Not to belabor the issue, but your understanding of the I-V curve and how it
responds to changes in irradiance and temperature are flawed. I'm sorry you
believe that I am misleading you, but the truth is that the I-V curve moves
up and down with changing irradiance (current changes with irr
ubject: Re: [RE-wrenches] Two strings of Different Orientation
Bill,
I agree with everything you're saying, if you substitute "cell temperature"
for "ambient temperature".
See ya!
Marv
707 763-4784 x7016
Bill Brooks wrote:
Peter,
Not to belabor the issue, but
Tump,
All I know is that AFCIs work off of the radio frequency signatures of arcs.
If your inverter has a lot of high frequency noise, typical in off-grid
inverters, it may be seeing this noise and thinking it is an arc. Marv
Dargatz, may have something to add on this. Also, relays in your charge
Carl and David,
Of course this means nothing related to the AstroPower warranty. The lawyers
at GE Energy were very careful to wait until AstroPower was officially dead
before they bought the Equipment to make modules from them. There is no
warranty--even though they are materially identical to th
n snowy locations.
PVWatts does not account for really dusty and dirty air locations. Bill Brooks
worked at PVUSA and is very knowledgeable about power loss from soiling from
agricultural dust in central California. Bill also measured 35% power loss at
the Long Beach CA harbor waste-to-ener
Joel and All,
PV:WATTS is just a very simple simulation. You can make simple corrections
for temp coefficient if you like, but if you want better accuracy, you have
to go to a more sophisticated program like PVSyst or PVSol.
Bill.
-Original Message-
From: re-wrenches-boun...@lists.re-wre
, but eventually the lead plan
checker was asked to make a presentation to the trade group and the handiest
document was our check list. It became adopted.
Bill Brooks has worked on this issue and has resources.
I suggest you start a dialog and then be quick and thorough on the follow up
and yo
Joel,
I don't have your email. I just happen to have 13 Shell SP-140s. My email is
billbroo...@sbcglobal.net.
Bill.
-Original Message-
From: re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Joel
Davidson
Sent: Wednesday, June 30, 2
Peter:
Here is a slide from one of my PV courses. This is my priority list for
module selection. The second item, qualification testing (IEC61215), is very
important if it has truly been done by a NRTL. Many companies claim to have
passed, but they performed the test themselves--invalidating the r
All,
This is all very interesting, but on the dc side, it is primarily an issue
of energy loss for large grid-connected systems. My rule is 2% voltage drop
for dc side and 1% for ac side.
When we talk about dc % voltage drop, most of what has been discussed in
this thread is instantaneous
Dave, Gary, and Charlie,
First, the directions from the manufacturer should be the guide as to
whether a GEC is required or not. Just because a GEC terminal is located on
the equipment, does not mean that one is required. Case in point-Enphase's
new IG product does not require a GEC, yet it has
Nick,
Thanks for the clarification-it is a mysterious threaded hole..
Bill.
From: re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Nick Soleil
Sent: Wednesday, September 18, 2013 10:19 AM
To: RE-wrenches
Subject: Re: [RE-wrenches]
William,
Here is what I would recommend.
1. Put pairs of SQ-150s in parallel on an M250.
2. Put PC4JFs as two in series by two in parallel on M250.
3. For leftovers-two PC4JFs in series are the same as one SQ-150 so
mix and match to your heart's content.
The issue
William,
Just to add one more thing. I said that the M215 does not match well, but if
you have them on hand, they would still work. You will probably power limit
in the spring and fall, but the rest of the year you will probably do fine.
The M250 has a higher operating voltage for 72-cell arran
Marco,
Besides the good responses you have already received, 20-30kW, 480V machines
are really targeting larger installations that would be on facilities with
480V. I would generally not build a system with 480V inverters on a 208V
service. For large systems, there are large inverters runnin
Howie,
I think your electrician friend either misheard John or John was wrong. I
believe the truth is that AC cable (aluminum clad) would have to be listed
for dc. The NEC is specific about the grounding capabilities of the MC. I am
unaware of any specific dc or ac requirements that MC has. There
Kirpal,
I'm not aware of a 15-degree allowance for NEMA 3R. Others on this forum may
be more familiar. Bottom line, if the installation instructions do no
specifically allow for an angle, you have to assume that vertical is the
only allowable orientation.
The only rooftop disconnects that
William and David,
This particular problem goes away with arc fault detection. The longer we
wait to introduce arc fault detection into our systems, the more we will
have opportunities for news reports such as the one William brings forward.
Wire ties are not the problem. Could a wire tie cause
not
helping at all. The trend has been to make it harder to protect wiring.
This trend will result in accidents. I think we should do better.
Sincerely,
William Miller
From: re-wrenches-boun...@lists.re-wrenches.org
<mailto:re-wrenches-boun...@lists.re-wrenches.org>
[mailto:r
nding electrode for PV
arrays.
He used everything short of drum rolls to build anticipation for this part
of the presentation.
Having personally contributed a short piece on this subject for SolarPro
magazine along with Bill Brooks and John Wiles in 2008, I looked forward to
this discussion. Finally, m
nominal voltage. Generally, this
is not a problem since an inverter that does not act quickly enough will
damage itself.
Bill.
Bill Brooks, PE
Principal
Brooks Engineering
3949 Joslin Lane
Vacaville, CA 95688
707-332-0761 (office and mobile)
b...@brooksolar.com (email)
www.brooksolar.com
ystem will result in a Class A
fire-rated roof-mounted PV system.
At least that's how I understood the presentation delivered by Christopher
Flueckinger from UL during the "Fire Safety" session at SPI in Chicago. I'm
sure Bill Brooks will chime in shortly and provide more clarit
Martin,
Regarding your reference to installations west of I-280 requiring Class A, I
did not find that in Palo Alto's materials. The City of Woodside fire
department was very involved in the CalFire Guidelines and I would not be
surprised if they implemented such a requirement. If you can find
Andy,
How are you testing the ground impedance of the EGC?
Bill.
From: re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Andrew
Truitt
Sent: Tuesday, January 14, 2014 7:25 AM
To: RE-wrenches
Subject: [RE-wrenches] EGC ground impeda
delivers more than we could
ever use in just about 8 minutes. And it's wireless!"
~William McDonough
On Tue, Jan 14, 2014 at 10:47 PM, Bill Brooks mailto:billbroo...@yahoo.com> > wrote:
Andy,
How are you testing the ground impedance of the EGC?
Bill.
Fr
subject since it was a very far-reaching and potentially
confusing new requirement in the NEC. Thanks for your interest and let's
keep the constructive dialogue going on the subject. It is time to get
involved in the NEC update process again.
Bill Brooks.
From: re-wrenches-boun...@lists.re
Brian,
The requirement is generic. A listed contactor can meet the requirement. A
standard is only necessary for products that want to be innovative in meeting
the 30V, 240VA. Killing all power is an option with existing listed equipment.
NEC 90.4 does not apply.
Bill.
From: re-wrenches
Frye
Sent: Tuesday, January 21, 2014 6:03 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] NEC 2014 690.12 Rapid Shutdown
OK. So I will have a high rate of acceptance if it buy an Tyco vacuum relay,
and mount it in a Hoffman enclosure, and then put it on my roof?
On 1/21/2014 5:45 PM, Bill Brooks
William,
One way to think about this is that temperature correction is used based on
the location of the ambient temperature you are concerned about.
Mostly, we are worried about the very high temperature of conductors in a
sunlit raceway on a roof. This gives us very high temperatures and we
Dan,
I believe you are referring to the Sedona fire when you talk of the
energized fence. I believe the fire department was in error when they
reported that the rooftop EMT energized the fence. It is pretty clear from a
review of the facts that the ac service drop burned free from the house and
Jeffrey and Ray,
Batteries can off-gas hydrogen-sulfide gas when under heavy charge or
overcharge. It is the nasty rotten egg smelling gas. Definitely not to be
inhaled since when it hits your lungs it turns back into sulfuric acid.
To address Ray’s point, the new 690.12 regulation that has
William and John,
A "320" as it is affectionately called is a 400-amp panel with a 320-amp
continuous duty. This is identical to two 200-amp panels that each has a
160-amp continuous duty-that we put 40-amp breakers into on a routine basis.
The "busbars" are rated for 200-amps each, just like a
Kirk,
There is no standard diameter for PV Wire so Chapter 9 table 1 must be used.
By the way, Table 1 is the code and the table in Annex C are not officially
the code. They are simply informational based on the standard nominal
diameters of various conductors. Many conductors have non-standard
Mark,
You should know better than anyone else that you can't corner the sun
market. If you read the reports you will find that your deepest fears are
unfounded.
Bill.
From: re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Mark Fry
WK, Marco, and William,
Agreed that 208V versus 240V is not an issue for 240V single phase loads.
Phase angle is not an issue for single phase loads--same reason that a
single-phase inverter can work with 208/240/277V. In the case of the
inverter, typically it is simply a winding count difference
Yes Peter,
It is called the 2012 International Fire Code. The California guidelines
were turned into code in 2012. There is an explanation document I wrote
available online at:
http://solarabcs.org//about/publications/reports/fireguideline/index.html
For those states that are using NFPA 1 as th
required of the building. At least that's the interpretation I
initially got from my local building and safety office. They've been sitting
on my plans for two weeks so far. When they turn them around, I may have
more to talk about.
/wk
William Korthof
714.875.3576
Sustainable Solution
Glenn,
The vast majority of service equipment for residences is rated 10k AIC.
Although utilities may say they have some residential services that exceed 10k
short circuit availability, it is still pretty rare.
Using single phase gear on a 3-phase commercial installation is a different
sto
William,
Go to http://www.associatedsoftwaresales.com/home.php . They do a 48-month
lease of 2013 AutoCAD LT for $325. If you really need AutoCAD, there is no
cheaper route that I know of.
Bill.
From: re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wre
re else in the panel
that changes this?
Glenn
From: 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 Bill Brooks
Sent: Wednesday, March 12, 2014 7:24 PM
To: 'RE-wrenc
Dave and Troy,
I don't think JW had his facts correct on this. The standard test for a
busbar is to place the highest allowable breakers directly below the main
breaker to test for overtemperature of the busbar. With the requirement for
Article 220 compliance of the panel, a panel that actually
Don and Garrison,
The word “dedicated” means “no loads”. That is why, the way the code is written
today, you cannot plug a microinverter into a wall outlet. There is no limit to
the number of inverters that can be placed on a single breaker. The limitation
for inverters, is the maximum overcu
nverters? Good, bad, or ugly?
Thanks,
Garrison
From: Bill Brooks [mailto:billbroo...@yahoo.com]
Sent: Friday, April 04, 2014 2:09 PM
To: 'RE-wrenches'; 'Garrison Riegel'
Subject: RE: [RE-wrenches] Three Inverters, One Disconnect?
Don and Garrison,
The word “dedicated
Aaron,
An exterior utility service panel with an underground service lateral is not
considered in or on the building.
Keep the dc conductors off of the building and you will be fine with a
ground-mounted PV system. Don't bring them inside the building, and don't
run them along the exterior of th
James,
This product is probably much like Rain-X. While you could put it on PV
modules, it would require reapplication on a fairly regular basis to keep it
working. As you pointed out, I don’t think many, if any, module manufacturers
that would specifically warranty their product with Rain-X
dule(s) or panel(s) secured
by removable fasteners and connected by a flexible
wiring system.
This is not a change. Please help me understand the concern.
Bill Brooks.
From: re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of R
Martin,
I agree that this would meet the requirement.
Bill.
From: re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Martin Herzfeld
Sent: Friday, May 02, 2014 10:49 AM
To: RE-wrenches
Subject: Re: [RE-wrenches] Rapid shutdown for pol
Kirk,
That is correct. Raceways are not rated for voltage. The key is whether the
conductor is intended to be installed in a raceway or not. Raceways are also
allowed to be used for physical protection only for direct buried cables and
exposed cables. The raceway is only required to prevent phy
-wrenches-boun...@lists.re-wrenches.org] On Behalf
Of Jay Peltz
Sent: Tuesday, May 27, 2014 11:32 AM
To: RE-wrenches
Subject: Re: [RE-wrenches] 2014 NEC
Hi nick
Good to know, I was told this by bill brooks at a training a few months ago.
Jay
Sent from my iPhone
On May 27, 2014, at 9:00 AM
Read this article from SolarPro:
“Array Voltage Considerations”, SolarPro Magazine, October/November 2010, pp
68-78.
Bill.
From: RE-wrenches [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf
Of Dana Brandt
Sent: Tuesday, June 03, 2014 3:42 PM
To: RE-wrenches
Subject: [RE-wrenc
m: RE-wrenches [mailto:re-wrenches-boun...@lists.re-wrenches.org] On
Behalf Of Bill Hoffer
Sent: Tuesday, June 03, 2014 9:00 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] Module Degradation - voltage or current?
Dana
Bill Brooks, passed on past data, ( correct me Bill if I am out of date
een it seems like panels that degrade at 0.5%/year are
outliers on the low side.
Thoughts from other wrenches?
On Tue, Jun 3, 2014 at 11:59 PM, Bill Hoffer mailto:suneng...@gmail.com> > wrote:
Dana
Bill Brooks, passed on past data, ( correct me Bill if I am out of date
Kirk and All,
I just got back from PV America and one of the venders there had a new PV
Wire that was a completely different construction (not XLP). Their outer
jacket is a more UV resilient material.
There are also PV Wire with PVC jackets that are less resilient to UV than
XLP. Ask for details
Jason,
It sounds like you want to get involved with the PV industry forum. We have
about 30+ active members this year so your input would be welcome.
I think your idea about organization needs to be informed about some details.
First of all, you need to read the new, very different, 705.12(
Kirk,
The tables in Appendix C are just for reference. They are not part of the Code.
The only real part of the code is in chapter 9:
Table 1 Percent of Cross Section of Conduit and Tubing for
Conductors and Cables
Number of Conductors and/or Cables Cross-Sectional Area (%)
1
Kirk,
I ran into a very similar problem with a system where the connectors were left
unmated for a period of time. Salts got into the connectors and whenever the
humidity was high, the salt would track current through the connector seals.
Replace all the connectors first before trying anything
Marco,
With "BP" on the module, it means a lot more than some no name brand. Just
because they are not producing anymore does not have any impact on their
warranty obligation unless BP goes out of business-that is not likely to
happen in your lifetime.
Bill.
From: re-wrenches-boun...@li
ches-boun...@lists.re-wrenches.org] On Behalf Of Bill Brooks
Sent: Tuesday, December 20, 2011 7:44 PM
To: 'RE-wrenches'
Subject: Re: [RE-wrenches] a PV titan is to be no more
Marco,
With "BP" on the module, it means a lot more than some no name brand. Just
because
http://solarprofessional.com/article/?file=SP4_3_pg14_QA_2
<http://solarprofessional.com/article/?file=SP4_3_pg14_QA_2&search=>
&search= (Bill Brooks article on Fuse Servicing disconnect requirements)
http://solarprofessional.com/article/?file=SP4_3_pg64_Hren
<http://solarprofessional.com/article
Joel,
It ain't over until it's over. The statewide effort will not limit
transformerless inverters if I have anything to do with it. This is
something these guys got on their brain, and they won't let it go-YET. Once
they understand better that these inverters are safer, we will get them to
bac
Andy, August, and Eric,
There will likely be significant changes in the 2014 NEC to clarify the
situation you are discussing. Fault current has very little to do with this
issue.
The key distinction was used in my proposal to the 2014 NEC that removed the
statement "and conductor" in 705.1
May 16, 2012 10:48 PM
> *Subject:* [RE-wrenches] Line side taps in Hawai'i
>
> Aloha Wrenches,
>
> I have recently started working in Hawaii on the island of Oahu and
> have run into some interesting problems with the AHJ's. The biggest
> issue is nobody is allowing lin
Benn,
This product appears to be significantly superior to the old-school ILSCO
tin-plated copper lugs. While those lugs may have been the best thing going
10 years ago, there have been many improvements. This looks like one of
them. I would argue with the statement that tin-plated copper is in
ugust 26, 2012 11:03 AM
To: RE-wrenches
Subject: Re: [RE-wrenches] Solmetric PVA and Tigo
On 8/26/2012 7:54 AM, Jesse Dahl wrote:
> Hello,
>
> Has anyone has experience using the Solmetric PVA and optimizers? Is
there any issues?
>
> Jesse
>
You might ask Bill Brooks. He has a
August,
Who at SMA said that they won't be shipping AFCI inverters? I know they have
been manufacturing. I have two of the AFCI inverters in operation at my
office and they are very impressive. Three months of operation since startup
without a single nuisance trip and it trips every time I simu
boB,
The limit of 80-volts was to make an exception for single module devices
like micro-inverters and for 48-volt battery systems and smaller. A change
controller operating above 80V would be required to have an AFCI whether on
or off grid if the array is mounted on a building.
Bill.
F
August,
I'm not really worried about residential center fed buswork since the 120%
exception only applied residential prior to the 2008 NEC and the location of
the OCPD was not specified.
The location of the OCPD was specified in the 2008 NEC to address commercial
panelboards that are run a
William,
Nice work on the wire management side. For you and others that may not be
aware, the U.S. Dept. of Energy funded the development of an online training
version of my Field Inspection Guide for PV Systems
(http://irecusa.org/wp-content/uploads/2010/07/PV-Field-Inspection-Guide-Jun
e-2010-F-
Marco,
This should be fairly straightforward. If the whole roof is truly grounded,
you have nothing to worry about. If it is not well grounded, then you have
cause for pause.
I would recommend the new Megger MIT410 (or420 or 430) device. It has a 50V
setting which is hugely beneficial for t
All,
Here is the language that has been accepted into the 2014 NEC:
690.31(C)(2)
(2) Cable Trays. PV source circuits and PV output circuits using
single-conductor cable listed and labeled as Photovoltaic (PV) wire of all
sizes with or without a Cable Tray marking/rating shall be permitt
William,
I would strongly disagree that conduit is tried and true on rooftops. I have
rarely seen good conduit runs on rooftops. Most electricians have no clue
how to work with expansion joints. Conduit on rooftops is a bad idea in
general. Most conduit runs in big buildings are all done indoor
Wrenches,
Fronius is releasing their AFCI inverters this month. They sent them to me
for CEC approval.
Bill.
From: re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Nathan
Stumpff
Sent: Tuesday, March 26, 2013 9:09 AM
To: re-wrenches
William,
I have all the respect in the world for you, but I'm not referring to
"basket tray", which is only appropriate for small conductors. I'm talking
about legitimate cable tray that can be up to 12" wide and that has a top
and rungs every 12". The main facilities that use it in the United
Carl,
Just to be clear, the performance tests mandated by the California Energy
Commission, that all products in the U.S. follow, require that the maximum
power rating is continuous (24/7). Actually, continuous means that it can
operate for 3 hours straight at 40C (104F) (really hot). This does
Troy,
Overcurrent device size is matched to the conductor size. The inverse time
constant nature of an overcurrent device can typically handle the surge
currents as long as conductor sizing has truly been done correctly for the
conductor. Circuit breakers are preferred to fuses because they can
Dave,
To add to your point, the typical way to wire an ungrounded PV system is to
use modules with PV Wire-connect them to homeruns of PV Wire-then transition
at some point to standard wire in raceways. This means that the only change
from a wiring method point of view is to use PV Wire whereve
Drake and all,
If I understand your thread, you are connecting through an extra 200-A
breaker in a box with two 200-A services. If this service was originating
from the utility, everything would be good and you would be making a
690.64(A) supply side service connection. If the connection at the ma
Drake,
690.64 relates everything to the service disconnects. All the rest of this
is semantics. As long as the PV connection is upstream of the service
disconnect (i.e. in between the service disconnect and the service meter),
it is considered a line side service connection.
If there is no
Drake,
They will not let you eliminate the box with the main breaker since the
conductors are run through the building. You are back to a load side
connection. However, since there are no loads pulled off that conductor to
the residential panel before the panel, connecting to the line side of t
Jeff and Ryan,
The 6kVA value comes from the California Rule 21 that I worked on. It only
applies to split-phase 240V systems (6kVA on 120V). There is no specific
limit for imbalance on a 3-phase service.
A basic rule for single phase generation on a 3=phase service is to rotate
among the phases
Allan,
You are leaving out the most important update in the code relative to the
Enphase inverter. The issue is covered in 690.14(D), Utility-Interactive
Inverters Mounted in Not-Readily Accessible Locations.
• Utility-interactive inverters shall be permitted to be mounted on
roofs o
Jay,
I believe Evergreen has had a variety of diode problems over the past year
or so. Not unlike several other manufacturers. Beware of inexpensive
off-shore modules. It is common for new manufacturers to underestimate the
design concerns with diodes. It's been going on for about 30 years.
Bill.
Doug,
I'd like to see the bulletin about why they could not positively ground
their modules. It seems quite odd.
Positively grounding a module in general should have no effect on a typical
module. As to why it helps the SunPower module, they have an explanation,
but I'm not convinced it is true-
William and Matt,
Roof absorptivity is the key (that is radiation absorptivity). You can
select some seemingly darker colors that have a lower absorptivity. However,
some lighter color roofings can have absorptivities has high as dark roofs.
The only way to know is to get the information from the
Geoff,
SS zip ties are good, but you must be very careful not to pull them tight.
They should only be snug, not tight. These SS zip ties have been shown to
cause ground faults in many cases. Commercial rooftops are accessible, but
not readily accessible. Conductors must be supported properly and p
Peter and all,
LADWP used to do a more comprehensive test. Off the record, an inverter did
fail that test because the manufacturer violated their listing (AEI--no
longer in business). To this person's knowledge may be correct. The problem
was addressed properly, but we don't want to get on our hig
Mark,
I'm surprised that you are disappointed and put so much stock in warranties.
Working with any new product and new company requires a go-slow mentality at
the start to establish a track record and field experience. A warranty is
only as valuable as the company behind the warranty. Enphase is
Rip,
Going down the road of engineering on every roof is a very slippery slope
(particularly with ice and snow). The idea that a roof designed for 30psf
would get in trouble with an additional 3psf is ridiculous. The Inspector
Guidelines that I wrote, which are based many jurisdictions across the
Thanks Jeff,
The multiple shingle layer argument is what is used in the Inspector
Guidelines. Thanks for a good overview of the issues.
Bill.
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Jeff Oldham
Sent: Tuesday, October 28, 2008 4:47 PM
To: re-wrenches@lists.re-wrenc
Kirpal,
When you parallel, your voltages have to be the same, so you are correct in
that assumption.
Your assumption about the diodes is not correct. Diodes don't work like
that. You could have a shorted module (all three diodes shorted) which would
lower the Voc by one module. It looks lik
Geoff,
The ultimate issue is how many cells are in each series string and is the
voltage of the cells nearly the same. As long as the number and the voltage
of the cells match up for each string, it makes no difference what
arrangement the modules are in.
You could have 5 + 6 + 7 = 18 cells
Peter,
PVWatts would be your first free option. Interesting way to specify module
power using efficiency and size. I don't believe there is quite enough
information to do a direct calculation. The assumptions in PVWatts are based
on location so it applies the single axis information. If really
101 - 200 of 236 matches
Mail list logo
