Re: [RE-wrenches] Module recommendation for a specific off grid situation

[Allan Sindelar]

Todd, thanks, but I rejected them. They'd be a traditional match as 36-cell modules, but they're way expensive (nearly $2/W Dlr.) and it would take 6 or 8 of them (140W these days) to get the ~kilowatt I'd like. It would work but I'm trying to keep the cost down. Allan Allan Sindelar al...@sindelarsolar.com NABCEP Certified PV Installation Professional NABCEP Certified Technical Sales Professional New Mexico EE98J Journeyman Electrician Founder (Retired), Positive Energy, Inc. 505 780-2738 cell   On 12/14/2015 2:29 PM, toddc...@finestplanet.com wrote: how about two of these in series? todd     On Monday, December 14, 2015 12:37pm, "Allan Sindelar" <al...@sindelarsolar.com> said: Wrenches, I enjoy the good feeling when I successfully integrate new with old - sort of a steampunk approach. Here's an example for which I could use the Collective Wisdom: A customer wants to upgrade a chronically small array on a maybe 10yo small off grid system done reasonably well by others. The array is four 165W Siemens (Solarworld) 72-cell modules on a top-of-pole rack, feeding an Outback MX60 controller on a 24V battery bank. To save cost in our rocky soil I'd like to add four large modern modules on a fixed ground mount rack, set fixed at latitude +5° for winter-focused gain. But most of the modern 72-cell modules use 156mm cells and are around 300W or higher. 1200W plus the existing 660W is 1860W, and that exceeds what the original MX60 is rated to handle. I know I could replace the controller with a Classic, but I wonder if there's a smaller compatible 72-cell module at a reasonable price. Any suggestions? I also think it would be best to use a module with a lower Vmp than I'd expect from the older Siemens modules, given that they're likely degraded a little in voltage over ten years (originally 35.3 Vmp rated). Does that make sense? So what if I used four 60-cell modules, expecting their higher current to pull the voltage of the original modules back a bit toward Isc. How much would that lose? I'll bet it wouldn't be much, and the cost would be low for the common modules, especially those with lower 240W rating or below. Again, any thoughts, please? And any suggestions of particular modules? Thanks, Allan -- Allan Sindelar al...@sindelarsolar.com NABCEP Certified PV Installation Professional NABCEP Certified Technical Sales Professional New Mexico EE98J Journeyman Electrician Founder (Retired), Positive Energy, Inc. 505 780-2738 cell   Sent from Finest Planet WebMail. _______________________________________________ List sponsored by Redwood Alliance List Address: RE-wrenches@lists.re-wrenches.org Change listserver email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out or update participant bios: www.members.re-wrenches.org

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