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Luke, I deleted your first message, but I thought you wrote that the system was pre-MPPT, with strings wired as 4 12 Vnom in series. IT seems to me that given insufficient Vmp, a modern controller is a no-brainer anyway, and it's only a matter to which one to use. A Classic 250 is the easy route that lets you solve a major problem with a simple and sensible component upgrade. It'll cost the customer nearly as much for a winter return trip to estimate Voc. But I agree with Jay and Randy: first check the existing array for failures. Allan Allan Sindelar On 5/31/2015 11:22 PM, Luke Christy
wrote:
Allen, With 8 modules in series I think I'll be looking at a Classic 250 for sure to be comfortable with winter morning VOC. I don't really know what kind of combiner situation I'll find up in the attic. It may be easy enough to re-wire into strings of 6 instead of strings of 8, though that is still probably going to push me just over the 150 VOC hard limit of the MX-60. I may not be able to get around replacing the controller.-Luke On May 31, 2015, at 10:59 PM, Allan Sindelar <al...@sindelarsolar.com> wrote:Jay, Whoa, I'd be careful there. Unless there's been a change while I was away on my bicycle, Outbacks are still 140V rated maximum voltage and 150V hard maximum. 142Voc in May suggests that doubling strings in series will easily exceed max Voc in winter. That's why I previously suggested Classic 200 or 250. Am I missing something? 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 5/31/2015 2:23 PM, jay peltz wrote:HI Luke, To add here. I'm unclear if you have measured each string or the whole array at 71v. I would check each string for voc/isc. And then if they are consistent, I agree that putting 2 strings in series with a new controller might help out. You can try it with the MX-60 as you are at only 142v. If it works better then a new higher voltage CC would be required for winter higher voc. Let us know what you find out. jayLuke Christy NABCEP Certified PV Installation Professional™: Certification #031409-25 NABCEP Certified Solar Heating Installer™: Certification #ST032611-03 CoSEIA Certified PV Installer Solar Gain Services, LLC PO Box 531 Monte Vista, CO. 81144 sgsrenewab...@gmail.com 719.588.3044 www.sgsrenewables.com _______________________________________________ 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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