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 <[email protected]> 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:* [email protected] > *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.... >
