<html><body><div style="color:#000; background-color:#fff; font-family:arial, helvetica, sans-serif;font-size:12pt"><div><span>I am on road so I have no texts with me, but the same formula applies about 0.4% per degree (less voltage) or use the module label voltage coefficent. However you must use the MPPT voltage and the temperature = (temperature ambient (2% high) plus roof temperature warming) The roof temperature is hard to find good values because it depends upon spacing between roof and module. I add 15 deg C for most situations. </span></div><div><span></span> </div><div><span>Best I can do from memory.</span></div><div><span>DT</span></div><div><br></div> <div style="font-family: arial, helvetica, sans-serif; font-size: 12pt;"> <div style="font-family: times new roman, new york, times, serif; font-size: 12pt;"> <font size="2" face="Arial"> <div style="margin: 5px 0px; padding: 0px; border: 1px solid
rgb(204, 204, 204); height: 0px; line-height: 0; font-size: 0px;" class="hr" contentEditable="false" readonly="true"></div> <b><span style="font-weight: bold;">From:</span></b> Kirk Herander <kirk@vtsolar.com><br> <b><span style="font-weight: bold;">To:</span></b> RE-wrenches <re-wrenches@lists.re-wrenches.org> <br> <b><span style="font-weight: bold;">Sent:</span></b> Tuesday, November 29, 2011 1:48 PM<br> <b><span style="font-weight: bold;">Subject:</span></b> [RE-wrenches] calculating low string voltage<br> </font> <br>
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--></style><div><div class="yiv1276106914WordSection1"><div class="yiv1276106914MsoNormal">I am in debate with a PE over calculation of low voltage of a series string on a hot day. He insists that an arbitrary high cell temp is factored in, not just ambient temperature. Could someone please give an accepted formula for this calculation? Thanks. I cannot find a clear reference to low voltage calculation on a hot day (but every reference material is clear on how to calculate high voltage on a cold day).</div><div class="yiv1276106914MsoNormal"> </div><div class="yiv1276106914MsoNormal">Kirk Herander</div><div class="yiv1276106914MsoNormal">VT Solar, LLC</div><div class="yiv1276106914MsoNormal">dba Vermont Solar Engineering</div><div class="yiv1276106914MsoNormal">NABCEP<sup>TM </sup>Certified installer Charter Member</div><div class="yiv1276106914MsoNormal">NYSERDA-eligible Installer</div><div class="yiv1276106914MsoNormal">VT RE Incentive Program
Partner</div><div class="yiv1276106914MsoNormal"> </div></div></div></div><br>_______________________________________________<br>List sponsored by Home Power magazine<br><br>List Address: <a href="mailto:RE-wrenches@lists.re-wrenches.org" ymailto="mailto:RE-wrenches@lists.re-wrenches.org">RE-wrenches@lists.re-wrenches.org</a><br><br>Options & settings:<br><a href="http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org" target="_blank">http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org</a><br><br>List-Archive: <a href="http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org" target="_blank">http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org</a><br><br>List rules & etiquette:<br>www.re-wrenches.org/etiquette.htm<br><br>Check out participant bios:<br>www.members.re-wrenches.org<br><br><br><br> </div> </div> </div></body></html>