Thursday, April 21, 2016

SunPower Solar Panels

(the install team lead taking a selfie at the end of the job)

We ordered a new plugin hybrid car through our local Audi dealer, and they had a deal setup with SunPower to install solar panels on your house - so, we did some research, compared prices, and we went ahead and signed with them.

We worked with SunPower and designed a 4kW system for our flat, but small roof. Our house is also in a bit of a narrow canyon, facing southwest, limiting our sun exposure. I understand most residential installations are about twice this size, but (aside from the expected uptick with the new car) we don't use much electricity. Over the last year or so we've been averaging about 6.6kWh per day; a typical American household uses about 30 kWh.

Interestingly, SunPower also got us onto a new billing rate with PG&E (E6), which allots us 8.5kWh per day. Our most recent electric bill was for about 180 kWh of electricity, about $30; but there was a Climate Credit that offset that $30 charge, so we paid nothing for that electricity - we did not have the panels yet. I'm not sure if that's math or alchemy.

So today was install day. It rained a bit but the team from Sun First! Solar (San Rafael) worked right thru and made a quick, professional job of it. There are 12 SunPower E20 panels rated at 327W each on two "strings" for a total of 3.9kW. A "Sunny Boy" DC-AC inverter is installed in the basement, with a shut-off near the main power meter.

SunPower estimates the system will generate about 4,800 kWh annually - a bit more than double our current use. So we can charge the car, and maybe even get air conditioning with a little less guilt. And just in time for Earth Day.