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 < re-wrenches@lists.re-wrenches.org> 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: RE-wrenches@lists.re-wrenches.org > > 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/re-wrenches@lists.re-wrenches.org/ > 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 > >
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