William - Over powering is not an issue. You might clip a little power occasionally, but the loss will be minute and you won't damage or void the warranty of the inverter. And since your talking separate strings, the current mismatch is a non-issue. The only loss you will incur will be due to your voltage mismatch, and I suspect it will be somewhere is the neighborhood of 2.5%
1 - (382 / 403) = .05 .05 / 2 = .025 Make sense? (I'm a little hung over so forgive me if it doesn't) Andrew Truitt Truitt Renewable Energy Consulting 202 486-7507 http://www.linkedin.com/pub/andrew-truitt/8/622/713 Please excuse brevity and typos - this message was typed on tiny keys. On Jan 15, 2011 11:44 AM, "William Miller" <[email protected]> wrote: Friends: I have a client with a Xantrex GT2.8 inverter. Feeding it are 8 Solar World SW175 modules. This is half the modules that this inverter can handle. The client wants to realize the full potential of this inverter. Adding 8 additional SW175 modules would be ideal, but they are no longer manufactured. I need to find a group of modules to match the 175s. I am contemplating 9 SW240s. The specifications for this match up are below. I imagine the IV curves are similar for these two modules as they are the same chemistry and the same manufacturer. 8-SW175 9-SW240 Voc 403 382 Vmp 283 275 Imp 4.95 7.87 Pcsi 1252 1715 Ptotal 2.967 Might this match be close enough? I know this over-powers the inverter slightly. I imagine that the Xantrex will self regulate this very rare over wattage condition. Comments? William Miller *Please note new e-mail address and domain: *William Miller Miller Solar Voice :805-438-5600 email: [email protected] http://millersolar.com License No. C-10-773985 _______________________________________________ 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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