<p>William - </p>
<p>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% </p>
<p>1 - (382 / 403) = .05<br>
.05 / 2 = .025</p>
<p>Make sense? (I'm a little hung over so forgive me if it doesn't)<br></p>
<p>Andrew Truitt<br>
Truitt Renewable Energy Consulting<br>
202 486-7507<br>
<a href="http://www.linkedin.com/pub/andrew-truitt/8/622/713">http://www.linkedin.com/pub/andrew-truitt/8/622/713</a><br><br><br></p>
<p>Please excuse brevity and typos - this message was typed on tiny keys.</p>
<p><blockquote type="cite">On Jan 15, 2011 11:44 AM, "William Miller" <<a href="mailto:william@millersolar.com" target="_blank">william@millersolar.com</a>> wrote:<br><br>
<div>
Friends:<br><br>
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.<br><br>
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.<br><br>
<font size="3"> 8-SW175 9-SW240<br>
Voc 403 382<br>
Vmp 283 275<br>
Imp 4.95 7.87<br>
Pcsi 1252 1715<br>
Ptotal 2.967<br><br>
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.<br><br>
Comments?<br><br>
William Miller<br><br>
<br><br>
<p>
<u>Please note new e-mail address and domain:<br><br>
</u>William Miller <br>
Miller Solar<br>
Voice :805-438-5600<br>
email: <a href="mailto:william@millersolar.com" target="_blank">william@millersolar.com</a><br>
<a href="http://millersolar.com/" target="_blank">http://millersolar.com<br>
</a>License No. C-10-773985<br>
</p></font></div>
<br>_______________________________________________<br>
List sponsored by Home Power magazine<br>
<br>
List Address: <a href="mailto:RE-wrenches@lists.re-wrenches.org" target="_blank">RE-wrenches@lists.re-wrenches.org</a><br>
<br>
Options & settings:<br>
<a href="http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org" target="_blank">http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org</a><br>
<br>
List-Archive: <a href="http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org" target="_blank">http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org</a><br>
<br>
List rules & etiquette:<br>
<a href="http://www.re-wrenches.org/etiquette.htm" target="_blank">www.re-wrenches.org/etiquette.htm</a><br>
<br>
Check out participant bios:<br>
<a href="http://www.members.re-wrenches.org" target="_blank">www.members.re-wrenches.org</a><br>
<br>
<br></blockquote></p>