This reply from Scott actually answered the original question. To that end, I would like to include my vote for the accuracy of his information.
Measurements conducted here at Exeltech affirm the ~30C temperature delta directly behind any cell near the center of the PV for an array with sufficient area to allow convective cooling. We have also found a few other variables impact cell temperature *slightly*, but not enough to worry about. The figures given by Scott below are as accurate a value as can be utilized. Dan Sr. Engineer Exeltech --- On Tue, 11/29/11, Scott McCalmont <[email protected]> wrote: From: Scott McCalmont <[email protected]> Subject: Re: [RE-wrenches] calculating low string voltage To: "RE-wrenches" <[email protected]> Date: Tuesday, November 29, 2011, 1:58 PM 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. Scott On Nov 29, 2011, at 11:48 AM, Kirk Herander wrote: 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). Kirk HeranderVT Solar, LLCdba Vermont Solar EngineeringNABCEPTM Certified installer Charter MemberNYSERDA-eligible InstallerVT RE Incentive Program Partner _______________________________________________ List sponsored by Home Power magazine List Address: [email protected] Options & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org -----Inline Attachment Follows----- _______________________________________________ List sponsored by Home Power magazine List Address: [email protected] Options & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
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