One week into our new lives as keepers of a photovoltaic electric generating station, we have some numbers to chew on. The first couple of days were crystal clear, cloudless wonders that we get here in the early spring. The array posted a daily output of about 27 kilowatt hours in full sun. Halfway through the week, as the days got cloudier but sill sunny, I washed down the array with a water hose, a push broom on a long handle and a bucket of mild detergent suds to knock of the coating of dust and pollen that was very noticeable when viewed from the side, not to mention the occasional splats of bird doody that are the inevitable result of placing the panels under the utility line. After a good wash they were sparkly new. By the end of the first week, the meter read 181 kWh. That day, yesterday, was very overcast, with thick dark clouds. Under these conditions the meter’s digital dial, sprightly like a march of ants on a sunny day, slows to a caterpillar crawl, and the system had added only 7 kWh to the power grid by the end of the day.
Two different entities pay us for our electricity: NC Greenpower, at 10 cents a kilowatt hour up to 7227kWh a year, and our electric utility co-op, which pays us a flat rate of 4.8 cents a kWh. The 7227 hour Greenpower limit represents about 140 kWh a month, or 19.8 kWh a day – about $2. Add in the approx $1 a day from the utility, that’s $3 a day, or $90 a month, or $1,095 a year. If we can sell our RECs (Renewable Energy Credits) for more, say 20 cents a kilowatt hour, it would bump up the numbers considerably – $4 a day plus $1 = $5 a day, or $150 a month, or $1,825 a year.