<div dir="ltr">Hi Jason, <div>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! </div><div><br></div><div>However, <a href="https://www.sciencedirect.com/science/article/pii/S0038092X21004837">this article </a>seems  helpful: <a href="https://www.sciencedirect.com/science/article/pii/S0038092X21004837">https://www.sciencedirect.com/science/article/pii/S0038092X21004837</a></div><div>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). </div><div><br></div><div>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<span style="color:rgba(0,0,0,0.85);font-family:".SF NS";font-size:26px"> </span><span style="color:rgba(0,0,0,0.85)"><font face="arial, sans-serif" style="">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. </font></span></div><div><span style="color:rgba(0,0,0,0.85)"><font face="arial, sans-serif" style="">Cheers, </font></span></div><div><span style="color:rgba(0,0,0,0.85)"><font face="arial, sans-serif" style="">Rebekah</font></span></div><div><span style="color:rgba(0,0,0,0.85)"><font face="arial, sans-serif" style=""><br></font></span></div><div><br></div>





<div><br clear="all"><div><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div><font color="#999999">Licensed Electrical Contractor<br>NABCEP Certified Solar PV Installation Professional™ 091209-85<br></font><div dir="ltr"><font color="#999999">Tel: 336.266.8800</font><br><br></div></div></div></div></div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Tue, Jan 30, 2024 at 9:04 AM Jason Szumlanski via RE-wrenches <<a href="mailto:re-wrenches@lists.re-wrenches.org">re-wrenches@lists.re-wrenches.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="auto">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. <div dir="auto"><br></div><div dir="auto">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? </div><div dir="auto"><br></div><div dir="auto">Jason Szumlanski</div><div dir="auto">Florida Solar Design Group </div></div>
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