boB, There is a chart in that white paper that graphs the losses on each module in the string. No significant losses seem to occur until you get to 5 in series
I can send the whole paper to you, or anyone, off list if you are interested Brian Teitelbaum AEE Solar bteitelb...@aeesolar.com From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of boB Gudgel Sent: Saturday, November 20, 2010 5:14 PM To: RE-wrenches Subject: Re: [RE-wrenches] Positive-ground question re Sunpower On 11/20/2010 4:36 PM, Mark Frye wrote: >From the 2006 white paper: "Polarization Incorrect grounding of SunPower modules can induce a surface charge which would lower the energy production. Previously SunPower has announced the discovery of the "surface polarization" effect which creates a non-destructive and reversible accumulation of static charge on the surface of high-efficiency solar cells such as SunPower's A-300 cells [9]. When the cells have a high positive voltage with respect to ground, How high though ?? I would think that there might be some curve that might show how high of V produces how much degradation ? I assume that the lower voltage modules in the string work better ?? Maybe it's the other way around and the high voltage modules work better when in a positive grounded system ? a negative static charge is built up on the surface of the cell due to current leakage through the glass and the highly insulating front surface anti-reflection coating of the cell. I bet (or hope) that they fix this some day by changing the composition of the glass, slightly, maybe. Nobody seems to talk about this except for this one paper that we see. boB This negative static charge causes increased surface recombination and the performance of the module is reduced. If the polarity is reversed and the cells are highly negative with respect to ground, the negative static charge is replaced by a positive static charge which restores the module performance." Mark Frye Berkeley Solar Electric Systems 303 Redbud Way Nevada City, CA 95959 (530) 401-8024 www.berkeleysolar.com<http://www.berkeleysolar.com/> ________________________________ From: re-wrenches-boun...@lists.re-wrenches.org<mailto:re-wrenches-boun...@lists.re-wrenches.org> [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of jay peltz Sent: Saturday, November 20, 2010 4:30 PM To: al...@positiveenergysolar.com<mailto:al...@positiveenergysolar.com>; RE-wrenches Subject: Re: [RE-wrenches] Positive-ground question re Sunpower Hi Allan, I have seen the white paper from Sunpower, ( but don't have a copy) that shows the losses as the voltage rises if using neg ground. But from memory, if using at low voltages such as two in series there should be minimal if any "loss" of watts. If you could use them as singles, for say a 12v system then there is no loss. Jay Peltz power _______________________________________________ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org<mailto: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<http://www.re-wrenches.org/etiquette.htm> Check out participant bios: www.members.re-wrenches.org<http://www.members.re-wrenches.org>
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