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<p class="MsoNormal">Good Morning;<o:p></o:p></p>
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<p class="MsoNormal">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.<o:p></o:p></p>
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<p class="MsoNormal">George McClellan | Senior Technical Sales Manager | REC Americas LLC
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330 James Way Ste 150<span lang="UK"> | </span>Pismo Beach, CA 93449<span lang="UK"> |
</span>USA<o:p></o:p></p>
<p class="MsoNormal">Cell phone +1 805 704 3226 | Fax +1 805 357 6104 <o:p></o:p></p>
<p class="MsoNormal"><span style="color:navy"><a href="http://www.recgroup.com/" title="http://www.recgroup.com/">www.recgroup.com</a>
</span><span style="color:black">| <a href="mailto:shannon.kent@recgroup.com">george.mcclellan@recgroup.com</a><o:p></o:p></span></p>
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<p class="MsoNormal"><b>From:</b> RE-wrenches <re-wrenches-bounces@lists.re-wrenches.org>
<b>On Behalf Of </b>Rebekah Hren via RE-wrenches<br>
<b>Sent:</b> Tuesday, January 30, 2024 6:26 AM<br>
<b>To:</b> RE-wrenches <re-wrenches@lists.re-wrenches.org><br>
<b>Cc:</b> Rebekah Hren <rebekah.hren@gmail.com><br>
<b>Subject:</b> Re: [RE-wrenches] Temperature coefficient versus Power<o:p></o:p></p>
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<p class="MsoNormal">Hi Jason, <o:p></o:p></p>
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<p class="MsoNormal">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! <o:p></o:p></p>
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<p class="MsoNormal">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><o:p></o:p></p>
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<p class="MsoNormal">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). <o:p></o:p></p>
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<p class="MsoNormal">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="font-size:19.5pt;font-family:".SF NS",serif"> </span><span style="font-family:"Arial",sans-serif">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. </span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-family:"Arial",sans-serif">Cheers, </span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-family:"Arial",sans-serif">Rebekah</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="color:#999999">Licensed Electrical Contractor<br>
NABCEP Certified Solar PV Installation Professional™ 091209-85</span><o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><span style="color:#999999">Tel: 336.266.8800</span><o:p></o:p></p>
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<p class="MsoNormal">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:<o:p></o:p></p>
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<p class="MsoNormal">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.
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<p class="MsoNormal">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? <o:p></o:p></p>
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<p class="MsoNormal">Jason Szumlanski<o:p></o:p></p>
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<p class="MsoNormal">Florida Solar Design Group <o:p></o:p></p>
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