<table cellspacing="0" cellpadding="0" border="0" ><tr><td valign="top" style="font: inherit;">This reply from Scott actually answered the original question.  To that end, I<br>would like to include my vote for the accuracy of his information.<br><br>Measurements conducted here at Exeltech affirm the ~30C temperature delta<br>directly behind any cell near the center of the PV for an array with sufficient<br>area to allow convective cooling.<br><br>We have also found a few other variables impact cell temperature *slightly*,<br>but not enough to worry about.<br><br>The figures given by Scott below are as accurate a value as can be utilized.<br><br><br>Dan<br>Sr. Engineer<br>Exeltech<br><br>
<br><br><br><br><br><br><br><br>--- On <b>Tue, 11/29/11, Scott McCalmont <i><re-wrenches@scottmccalmont.com></i></b> wrote:<br><blockquote style="border-left: 2px solid rgb(16, 16, 255); margin-left: 5px; padding-left: 5px;"><br>From: Scott McCalmont <re-wrenches@scottmccalmont.com><br>Subject: Re: [RE-wrenches] calculating low string voltage<br>To: "RE-wrenches" <re-wrenches@lists.re-wrenches.org><br>Date: Tuesday, November 29, 2011, 1:58 PM<br><br><div id="yiv1313511410"><base><div>Usually you increase the temperature above ambient by an amount which depends on the mounting method. Close to the roof is +35 degrees C, more than 6 inches above the roof is +30 degrees C, and pole or ground mount is +25 degrees C.<div><br></div><div>Scott<br><div><br><div><div>On Nov 29, 2011, at 11:48 AM, Kirk Herander wrote:</div><br class="yiv1313511410Apple-interchange-newline"><blockquote type="cite"><span class="yiv1313511410Apple-style-span"
 style="border-collapse:separate;font-family:Helvetica;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;orphans:2;text-indent:0px;text-transform:none;white-space:normal;widows:2;word-spacing:0px;font-size:medium;"><div lang="EN-US"><div class="yiv1313511410WordSection1" style=""><div style="margin-top:0in;margin-right:0in;margin-left:0in;margin-bottom:0.0001pt;font-size:11pt;font-family:Calibri, sans-serif;">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
 style="margin-top:0in;margin-right:0in;margin-left:0in;margin-bottom:0.0001pt;font-size:11pt;font-family:Calibri, sans-serif;">  </div><div style="margin-top:0in;margin-right:0in;margin-left:0in;margin-bottom:0.0001pt;font-size:11pt;font-family:Calibri, sans-serif;">Kirk Herander</div><div style="margin-top:0in;margin-right:0in;margin-left:0in;margin-bottom:0.0001pt;font-size:11pt;font-family:Calibri, sans-serif;">VT Solar, LLC</div><div style="margin-top:0in;margin-right:0in;margin-left:0in;margin-bottom:0.0001pt;font-size:11pt;font-family:Calibri, sans-serif;">dba Vermont Solar Engineering</div><div style="margin-top:0in;margin-right:0in;margin-left:0in;margin-bottom:0.0001pt;font-size:11pt;font-family:Calibri, sans-serif;">NABCEP^{TM<span class="yiv1313511410Apple-converted-space"> </span>}Certified installer Charter Member</div><div
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