Friends, Help disabuse this old timer of his outdate notions:
crystalline modules MPPT tracking inverter a sting of modules operate at max power in full sun shading causes enough cells in the first substring in the first module to go into resistance to the point that the substring "turns off" and the current of the full string is shunted through the substring bypass diode the following power losses occur: 1 - the power of the substring is lost completely 2 - power is lost in the bypass diode AND 3 - power is lost becasue the remaining cells in the system can no longer operate at their max power point progressively shading more and more substrings eventually causes the output power to collapes when the operating voltage of the string drops below the MPPT tracking window. I have always thought that #3 above was very significant such that power loss with progressivley increasing shading was on the order of the square of the percentage of shading ( you loss "x" percent of your productive cells and the remaining cells operate "x" percent below their max power) a collegue pulled out a PVSyst simulation that stacked the I/V curves for this scenario and it basic showed a linear reduction in power relattive to the amount of shading Have I been wrong in my thinking all along? Thanks, Mark Frye Berkeley Solar Electric Systems _______________________________________________ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Change email address & 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
