I have to respectfully disagree, in WA and BC the mid winter sunlight hours are even fewer. But 12 x 345W panels tilted at 80 degrees facing directly south will produce far more than enough kWh/mo for a particular type of site's calculated needs, in December and January. Battery voltage monitoring systems are set up and a portable generator can be brought to the site if needed during those two months.
Predicted production is about 247kWh a month in December. Load, which is all DC, is below 90 kWh/mo. On Tue, Jun 20, 2017 at 8:29 PM, Sean Heskett <af...@zirkel.us> wrote: > Totally agree with Chuck on this line of thought. Where we are (NW > ColoRADo) there is no amount of panels + batts you can install for Dec & > Jan. Propane generator is the only way to keep an off grid site running. > YMMV > > -Sean > > > > On Tue, Jun 20, 2017 at 5:17 PM Chuck McCown <ch...@wbmfg.com> wrote: > >> Remote start propane generator is a much better value for sites like >> this. In the middle of winter have a low voltage relay trigger the >> generator. Run it just long enough to top the batts. Usually an hour a >> day is more than enough. Store enough propane to get through the worst of >> it. >> >> *From:* Eric Kuhnke >> *Sent:* Tuesday, June 20, 2017 6:00 PM >> *To:* af@afmug.com >> *Subject:* Re: [AFMUG] Vendor for super high efficiency (Sunpower,etc) >> PV panels >> >> I care about efficiency because in some cases space is at a premium. If >> these were going on the roof of a warehouse/office type building I would >> agree. But in a place where it is 4x4 access only, and only in summer, >> there is a scenario where a big ground mount tilted at 80 degrees for off >> grid will only hold 12 x 72-cell panels (2.0 x 1.0m each). >> >> Going any bigger than that for square footage of panels and size of mount >> will drive up the cost considerably. The site I am building right now has >> 12 x 345W 72-cell panels, and I am looking at a configuration with 12 x >> 360W panels for the next one. The goal is the greatest possible kWh >> production in December and January and additional safety margin for >> extended periods of cloudy days in mid winter. >> >> >> >> On Tue, Jun 20, 2017 at 6:58 AM, Chuck McCown <ch...@wbmfg.com> wrote: >> >>> I use 11 watts per square foot as a rule of thumb. Never wanted >>> efficiency, always wanted low $/watt. >>> >>> *From:* Eric Kuhnke >>> *Sent:* Monday, June 19, 2017 6:47 PM >>> *To:* af@afmug.com >>> *Subject:* [AFMUG] Vendor for super high efficiency (Sunpower, etc) PV >>> panels >>> >>> Anyone have a favorite vendor source for >21% efficient PV panels they'd >>> like to share? >>> >>> I'm looking at various commodity 60 and 72-cell modules made with 4.95 >>> to 5.0W high efficiency 156mm monocrystalline cells, but the Sunpower mono >>> stuff is still better in STC watts per square foot. >>> >>> 60-cell x 5W = 300W >>> 72-cell x 5W = 360W >>> >>> >>> Of course, willing to pay somewhat of a price premium.... >>> >> >> >
