Word of caution... don't wire the bigger SunPower modules with the negative conductor grounded. With the metal frame grounded, as it should be, this combination causes a strange surface polarization effect that will discolor the cells and cause the power output to drop by about half. Fortunately the polarization and discoloring are totally reversible if the system is re-wired with the positive conductor grounded (as we found out, even after 6 months of being wired incorrectly), but it takes a few days to correct. For this same reason, SunPower modules can't be used with bipolar inverters.
Jeff Irish Hudson Valley Clean Energy ________________________________ From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of jay peltz Sent: Friday, March 20, 2009 9:39 AM To: RE-wrenches Subject: Re: [RE-wrenches] Sunpower modules Hi Larry, I was under the impression that Sunpower were only for on grid? And for off grid with the low voltages that we use, they are still requiring you to use positive ground? I've seen the white paper they did and it showed at lower voltages there is no need to positive ground, thats why for example those 90 watt panels using Sunpower cells are used with Negative ground. curious, jay peltz power On Mar 19, 2009, at 9:14 PM, Larry Crutcher, Starlight Solar wrote: William, I know you asked Jeff but thought I would respond as all we do are off grid, battery based systems. I typically see that the Vmp voltage of Sunpower modules is closer to spec with than with Kyocera, Sharp or Mitsubishi. In my opinion Sunpower modules are only surpassed by Sanyo. I realize this is anecdotal but after hundreds of installs you begin to notice these things. Larry Crutcher On Mar 19, 2009, at 5:46 PM, William Miller wrote: Jeff: Have these modules worked for you in battery based systems? William Mill At 01:27 PM 3/19/2009, you wrote: Hiya Jeff, You are correct that the sunpower modules are positively grounded. You are also correct that sunpower only deals with dedicated "dealers". That means that if you are not one of their dealers you cannot get their panels. It is my understanding that sunpower is always looking for new dealers, so you may want to check in with them. As far as architectural review committees and such, we have never had a problem using SPR modules in the areas where review is an issue. The positive ground really does not affect aanything. Instead of your negative wire being the grounded (white) conductor it is your positive conductor that is grounded. This means you are switching the negative instead of the positive in the DC disco. Sunpower sells packaged systems, so they provide positive ground inverters from different manufacturers. Evergreen now has a black framed module, and I believe Sharp does too. I hope this helps, any other questions feel free to contact me. Jeff Blick Lead PV Installer _______________________________________________ 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
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