Affordable high efficiency 72-cell panels are, in STC rating: http://sinovoltaics.com/learning-center/quality/standard-test-conditions-stc-definition-and-problems/
330W 2.0 x 1.0 meter size = 172W/square meter STC Or very nearly the same for 60-cell (1.65 x 1.0 meter) panels, at 175 to 181 W/sq meter. Really high efficiency but more expensive panels, made of the top tier mono cells, are now at 210-215 STC W per square meter. Have not purchased any yet. But those were the main focus of my original post, to figure out how significant the cost difference is vs. $0.52/watt 345W panels. And figure out possible vendor sources. On Wed, Jun 21, 2017 at 7:27 AM, <ch...@wbmfg.com> wrote: > 90 kWh/mo load is a 123 watt load. (123*24*30.4) > 123 * 20 = 2460 watts My rule of thumb for Utah. Assuming you have 2 > weeks of batts that is all you will need. > > You have 4140 watts of panel. That is 33X. No doubt it will work. > Probably produces usable current in moonlight. Certainly overcast power. > During a light overcast you get 5% power. If you are 20x load, you are > fully powering the load during overcast. > > Now, in my case, that extra 1680 watts of panel that I would not have > installed would have paid for the generator and propane tank. > > So, 33X in WA and BC, 20X in Utah no generator. 10X in Utah with > generator. (and that is cutting it thin). > > > *From:* Eric Kuhnke > *Sent:* Tuesday, June 20, 2017 9:34 PM > *To:* af@afmug.com > *Subject:* Re: [AFMUG] Vendor for super high efficiency (Sunpower,etc) PV > panels > > 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.... >>>> >>> >>> >> >
