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.... >> > >
