I would recommend testing the temp gun against other sensors like a thermocouple and the DAS if it’s available.
Brian > On Nov 3, 2020, at 1:18 PM, Jason Kechijian <[email protected]> wrote: > > Hey Brian, > > Following up on both sets of questions: > > Can you attach the spec sheet? Does it show curves at different irradiances? > — ATTACHED > > What was the time of day (or was it just cloudy?). — ~11:00am > > How are you measuring the cell temp? — Fluke Temp gun (new battery) > > The string voltages were +/- 1.5% of adjacent > > Meter — Hioki CM4374 (calibrated recently) > > Testing a single module, while ideal, is not practical unless we run into > issues. I should have the ~480 strings worth of measured data back later > today. > > >> On Nov 3, 2020, at 2:52 PM, Brian Mehalic <[email protected]> wrote: >> >> Hey Jason, IEC 62446-1 allows for: >> >> Testing Voc of a single module and using that to calc the target string >> voltage >> and >> "For systems with multiple identical strings and where there is stable >> irradiance conditions, voltages between strings can be compared" >> >> Regardless, it would be interesting to have a test on a single mod (well >> some number of single mods). >> >> What meter are you using, and has it been calibrated recently? >> >> >> Brian Mehalic >> NABCEP Certified Solar PV Installation Professional™ R031508-59 >> National Electrical Code® CMP-4 Member >> (520) 204-6639 >> >> Solar Energy International >> http://www.solarenergy.org >> >> SEI Professional Services >> http://www.seisolarpros.com >> >> >> >> On Tue, Nov 3, 2020 at 10:32 AM Brian Mehalic <[email protected]> wrote: >>> A few more questions: >>> >>> Can you attach the spec sheet? Does it show curves at different irradiances? >>> >>> What was the time of day (or was it just cloudy?). >>> >>> How are you measuring the cell temp? >>> >>> Brian >>> >>> > On Nov 3, 2020, at 8:50 AM, Jason Kechijian <[email protected]> wrote: >>> > Hey Jay and Brian, >>> > >>> > System: 2p SAT >>> > Mods/String: 27 >>> > >>> > Measurements taken on average of CB >>> > Ambient: ~23ºC >>> > Module: 21.4ºC >>> > Wind: moderate >>> > Irradiance: 500W/m2 >>> > >>> > Expected Voc: 1,320.37 >>> > >>> > Testing based on IEC 62446 >>> > Measured Voc on a range of 9 string combiner: 1251 - 1271. 1251 being the >>> > only string in the CB at less than 5% of expected, which I am sure the >>> > wind had some effects. All voltages in the CB were +/- 1.5% of the >>> > adjacent. >>> > >>> > I’ll share more results as the come in from the field. >>> > >>> > The questions: >>> > Which of the two Vocs should we use? The average of the two? >>> > Since we are not taking the BOM temp measurements from a back sheet, but >>> > rather a cell. What does the thermal effect of glass play on the >>> > temperature reading vs. the back sheet. (May be wording this wrong, but I >>> > think y’all get the point) >>> > >>> > I have searched the inter webs and not found much guidance/support in >>> > particular to this query. >>> > >>> > >>> > Jason Kechijian >>> > >>> > >>> >> >>> >> >>> >> Hey wrenches, >>> >> >>> >> Does anyone have any guidance to which values to use when testing open >>> >> circuit voltage on bi-facial modules, considering you take the >>> >> temperature reading from the cell vs. the back sheet? Also, what would >>> >> be the correct module Voc to use since there are values for both the >>> >> front and back? >>> >> >>> >> 405W Module: Front/Back >>> >> Pmpp: 405 / 285 >>> >> Vmpp: 40.89 / 41.10 >>> >> Impp: 9.91 / 6.94 >>> >> Voc: 48.42 / 46.99 >>> >> Isc: 10.38 / 7.28 >>> >> Module efficiency: 19.7% / 13.9% >>> >> Temp coefficient Pmpp: -0.3528%/?C >>> >> Temp coefficient Isc: +0.0400%/?C >>> >> Temp coefficient Voc: -0.2769%/?C >>> >> Nominal: 44+/-2?C >>> >> >>> >> I was using the front Voc and Voc temp coefficient, but I am getting >>> >> some results which are not in line with the 5% of expected. >>> >> >>> >> Jason D. Kechijian, LEED AP >>> >> NABCEP Certified PV Installation Professional? >>> >> >>> >> >>> >> >>> >> >>> >> >>> >> ------------------------------ >>> >> >>> >> Message: 2 >>> >> Date: Mon, 2 Nov 2020 08:25:20 -0700 >>> >> From: Jay <[email protected]> >>> >> To: RE-wrenches <[email protected]> >>> >> Subject: Re: [RE-wrenches] Bi-facial Open Circuit voltage testing >>> >> Message-ID: <[email protected]> >>> >> Content-Type: text/plain; charset=utf-8 >>> >> >>> >> Hi Jason, >>> >> >>> >> What are you seeing in terms of measurements? >>> >> >>> >> Temp air/module >>> >> Voc >>> >> Irradiance >>> >> Etc >>> >> >>> >> Jay >>> >> Peltz power >>> >> >>> >> >>> >> Message: 3 >>> >> Date: Mon, 02 Nov 2020 08:41:21 -0800 >>> >> From: Dave Angelini Offgrid Solar <[email protected]> >>> >> To: "RE-wrenches" <[email protected]> >>> >> Subject: Re: [RE-wrenches] Bi-facial Open Circuit voltage testing >>> >> Message-ID: <[email protected]> >>> >> Content-Type: text/plain; charset=UTF-8 >>> >> >>> >> I am curious why you care? Is it close to maxing out cold weather Voc >>> >> for >>> >> one more panel in the string? If so I would be conservative and use one >>> >> less panel. >>> >> >>> >> I have an old Sanyo Bi Array and it pretty much has never gone outside >>> >> the >>> >> cold weather Voc that is logged by the controller. The 600v mppt just >>> >> cranks out the power when the snow is off the array. It does pretty well >>> >> also when the snow is on it. >>> >> >>> >> Just curious what you are doing? Testing used panels to make sure they >>> >> are >>> >> good? If so I would line them all up exactly the same and have a second >>> >> set >>> >> of eyes to record it all. >>> >> >>> >> >>> >> Dave Angelini Offgrid Solar >>> >> "we go where powerlines don't" >>> >> http://members.sti.net/offgridsolar/ >>> >> e-mail [email protected] >>> >> text 209 813 0060 >>> >> >>> >> >>> >> ------------------------------ >>> >> >>> >> Message: 4 >>> >> Date: Mon, 2 Nov 2020 09:53:43 -0700 >>> >> From: Brian Mehalic <[email protected]> >>> >> To: RE-wrenches <[email protected]> >>> >> Subject: Re: [RE-wrenches] Bi-facial Open Circuit voltage testing >>> >> Message-ID: >>> >> <capkgs9tz6yehzweoardp0mvamhuxmfhcluoprowetxynew0...@mail.gmail.com> >>> >> Content-Type: text/plain; charset="utf-8" >>> >> >>> >> I second Jay's request for some numbers, I'm curious about this not >>> >> having >>> >> participated directly in any bifacial projects yet. The difference in >>> >> Voc >>> >> and Vmp ratios is interesting. >>> >> >>> >> Brian Mehalic >>> >> NABCEP Certified Solar PV Installation Professional? R031508-59 >>> >> National Electrical Code? CMP-4 Member >>> >> (520) 204-6639 >>> >> >>> >> Solar Energy International >>> >> http://www.solarenergy.org >>> >> >>> >> SEI Professional Services >>> >> http://www.seisolarpros.com >>> >> >>> >> >>> >> >>> >>> On Mon, Nov 2, 2020 at 8:55 AM Jay <[email protected]> wrote: >>> >>> Hi Jason, >>> >>> What are you seeing in terms of measurements? >>> >>> Temp air/module >>> >>> Voc >>> >>> Irradiance >>> >>> Etc >>> >>> Jay >>> >>> Peltz power >>> >>>> On Nov 2, 2020, at 8:18 AM, Jason Kechijian <[email protected]> wrote: >>> >>>> ?Hey wrenches, >>> >>>> Does anyone have any guidance to which values to use when testing open >>> >>> circuit voltage on bi-facial modules, considering you take the >>> >>> temperature >>> >>> reading from the cell vs. the back sheet? Also, what would be the >>> >>> correct >>> >>> module Voc to use since there are values for both the front and back? >>> >>>> 405W Module: Front/Back >>> >>>> Pmpp: 405 / 285 >>> >>>> Vmpp: 40.89 / 41.10 >>> >>>> Impp: 9.91 / 6.94 >>> >>>> Voc: 48.42 / 46.99 >>> >>>> Isc: 10.38 / 7.28 >>> >>>> Module efficiency: 19.7% / 13.9% >>> >>>> Temp coefficient Pmpp: -0.3528%/?C >>> >>>> Temp coefficient Isc: +0.0400%/?C >>> >>>> Temp coefficient Voc: -0.2769%/?C >>> >>>> Nominal: 44+/-2?C >>> >>>> I was using the front Voc and Voc temp coefficient, but I am getting >>> >>> some results which are not in line with the 5% of expected. >>> >>>> Jason D. Kechijian, LEED AP >>> >>>> NABCEP Certified PV Installation Professional? >>> >>>> _______________________________________________ >>> >>>> List sponsored by Redwood Alliance >>> >>>> List Address: [email protected] >>> >>>> Change listserver email address & settings: >>> >>>> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >>> >>>> There are two list archives for searching. When one doesn't work, try >>> >>> the other: >>> >>>> https://www.mail-archive.com/[email protected]/ >>> >>>> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org >>> >>>> List rules & etiquette: >>> >>>> http://www.re-wrenches.org/etiquette.htm >>> >>>> Check out or update participant bios: >>> >>>> http://www.members.re-wrenches.org >>> >>> _______________________________________________ >>> >>> List sponsored by Redwood Alliance >>> >>> List Address: [email protected] >>> >>> Change listserver email address & settings: >>> >>> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >>> >>> There are two list archives for searching. When one doesn't work, try >>> >>> the >>> >>> other: >>> >>> https://www.mail-archive.com/[email protected]/ >>> >>> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org >>> >>> List rules & etiquette: >>> >>> http://www.re-wrenches.org/etiquette.htm >>> >>> Check out or update participant bios: >>> >>> http://www.members.re-wrenches.org >>> >> -------------- next part -------------- >>> >> An HTML attachment was scrubbed... >>> >> URL: >>> >> <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20201102/013a4e3f/attachment-0001.html> >>> >> >>> >> ------------------------------ >>> >> >>> >> Subject: Digest Footer >>> >> >>> >> _______________________________________________ >>> >> List sponsored by Redwood Alliance >>> >> >>> >> List Address: [email protected] >>> >> >>> >> Change listserver email address & settings: >>> >> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >>> >> >>> >> There are two list archives for searching. When one doesn't work, try >>> >> the other: >>> >> https://www.mail-archive.com/[email protected]/ >>> >> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org >>> >> >>> >> List rules & etiquette: >>> >> http://www.re-wrenches.org/etiquette.htm >>> >> >>> >> Check out or update participant bios: >>> >> http://www.members.re-wrenches.org >>> >> >>> >> >>> >> >>> >> ------------------------------ >>> >> >>> >> End of RE-wrenches Digest, Vol 13, Issue 367 >>> >> ******************************************** >>> > >>> > _______________________________________________ >>> > List sponsored by Redwood Alliance >>> > >>> > List Address: [email protected] >>> > >>> > Change listserver email address & settings: >>> > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >>> > >>> > There are two list archives for searching. When one doesn't work, try the >>> > other: >>> > https://www.mail-archive.com/[email protected]/ >>> > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org >>> > >>> > List rules & etiquette: >>> > http://www.re-wrenches.org/etiquette.htm >>> > >>> > Check out or update participant bios: >>> > http://www.members.re-wrenches.org >> _______________________________________________ >> List sponsored by Redwood Alliance >> >> List Address: [email protected] >> >> Change listserver email address & settings: >> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >> >> There are two list archives for searching. When one doesn't work, try the >> other: >> https://www.mail-archive.com/[email protected]/ >> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org >> >> List rules & etiquette: >> http://www.re-wrenches.org/etiquette.htm >> >> Check out or update participant bios: >> http://www.members.re-wrenches.org >> > > _______________________________________________ > List sponsored by Redwood Alliance > > List Address: [email protected] > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > There are two list archives for searching. When one doesn't work, try the > other: > https://www.mail-archive.com/[email protected]/ > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > http://www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > http://www.members.re-wrenches.org >
_______________________________________________ List sponsored by Redwood Alliance List Address: [email protected] Change listserver email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org There are two list archives for searching. When one doesn't work, try the other: https://www.mail-archive.com/[email protected]/ http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: http://www.re-wrenches.org/etiquette.htm Check out or update participant bios: http://www.members.re-wrenches.org
