|
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 |
_______________________________________________ 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
