Mark, Think about this: the Isc current is only slightly higher than Imp. Picture a series DC circuit. Both short circuit and operating current are loads on the PV module(s). An indefinite short will not be a problem any more than operating the module at higher than 1000W/M/2. Neither will there be any more potential for hot spot damage than in normal operation.
When you cut the jumper, watch out for the arc! Larry Crutcher Starlight Solar Power Systems On Sep 17, 2012, at 9:50 PM, Mark Frye wrote: Wrenches, True or False: In a nominal sort of grid tied situation with string Voc at about 300 VDC and Isc at about 6 or 7 amps......It is OK to install modules on a roof in the sun and short the pos and neg together indefinitely. In other words modules can handle operating at Isc continuously without damage. It is only if you get localized shading AND a failed bypass diode that damaging hot spot heating can lead to failure? I am reviewing an installation manual that recommends completing the home run by connecting the pos and neg of the string with a single jumper cable, folding the cable on itself in order to push it through to a j-box and at some point later on, cutting the jumper in the j-box to terminate the pos and negs to the home run. I am concerned both about maintaining the string in a short circuit condition and cutting the jumper while energized. Any thoughts? Mark Frye Berkeley Solar Electric Systems _______________________________________________ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org 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 _______________________________________________ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org 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
