Good Morning; Excellent update Rebekah (someone is up early). Module voltage stays pretty linear as irradiance varies and temp stays constant. Currently the industry calls this linear, but as the whitepaper Rebekah posted shows, it is not truly linear. [cid:[email protected]]
George McClellan | Senior Technical Sales Manager | REC Americas LLC 330 James Way Ste 150 | Pismo Beach, CA 93449 | USA Cell phone +1 805 704 3226 | Fax +1 805 357 6104 www.recgroup.com<http://www.recgroup.com/> | [email protected]<mailto:[email protected]> From: RE-wrenches <[email protected]> On Behalf Of Rebekah Hren via RE-wrenches Sent: Tuesday, January 30, 2024 6:26 AM To: RE-wrenches <[email protected]> Cc: Rebekah Hren <[email protected]> Subject: Re: [RE-wrenches] Temperature coefficient versus Power Hi Jason, That's an interesting question, as typically it is stated that temperature coefficients are linear, however the "linearity" is with respect to the temperature variable, not power (irradiance) I have always assumed that tkPmp is fairly linear with respect to power, but now that you mention it I don't have much basis for that assumption! However, this article <https://www.sciencedirect.com/science/article/pii/S0038092X21004837> seems helpful: https://www.sciencedirect.com/science/article/pii/S0038092X21004837 Scroll all the way down to section 4.3, and it appears that there are only very minor variations in tkPMP with low to high irradiance (power). As that chart shows, tkVoc varies more significantly with irradiance, but I do think the industry realizes that and factors it in with the allowance in NEC 690.7 to calculate maximum voltage based on SAND 2004-3535, Photovoltaic Array Performance Model, which takes into account the effect that low irradiance has on voltage - you can see the lower tkVOC at lower irradiances. Cheers, Rebekah Licensed Electrical Contractor NABCEP Certified Solar PV Installation Professional™ 091209-85 Tel: 336.266.8800 On Tue, Jan 30, 2024 at 9:04 AM Jason Szumlanski via RE-wrenches <[email protected]<mailto:[email protected]>> wrote: I'm having a hard time finding concrete information on the relationship of temperature coefficient and power output. Solar panel temperature coefficients are determined at Pmax. My question is, at lower irradiance levels, say where power output would be 50% of Pmax at 25C, would the temperature coefficient be greater, less, or the same? Jason Szumlanski Florida Solar Design Group _______________________________________________ List sponsored by Redwood Alliance Pay optional member dues here: http://re-wrenches.org List Address: [email protected]<mailto:[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 ________________________________ This message is private and confidential and may be privileged. Any unauthorized use, dissemination of the information or copying of this message is prohibited. If you have received this message in error, please notify us immediately and remove it from your system. Thank you. ________________________________ This message is private and confidential and may be privileged. Any unauthorized use, dissemination of the information or copying of this message is prohibited. If you have received this message in error, please notify us immediately and remove it from your system. Thank you.
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