Our recently installed 12.635kW photovoltaic array produced over 20kWh (kilowatt-hours) of electricity during the last partly-sunny twenty-four hours. Needless to say, nine days before the winter solstice at this high latitude is the nadir of productivity for the system; it should do great things when the sun starts back in this direction.
As blogged previously, this system isn’t justified economically even with a Vermont rebate, a federal tax credit, the right to sell excess electricity back to the grid at retail prices (up to the amount of our annual bill), and locally high electric rates. The forgone interest on the capital that goes into the system is still greater than the annual savings in electricity. You can make the math work out if you predict escalating electricity prices (not a bad bet); but you could also wait for the prices to rise and then install the system. It’s even likely that the prices of photovoltaic cells will fall and their efficiency rise if you wait.
On the other hand, you can’t cost-justify a fancy car or fine landscaping or art either. You have to weight the money you spend against the enjoyment you get. I will greatly enjoy seeing my electric meter run backwards. And I’m now looking forward to finding ways to use all the electricity we can generate to displace imported fossil fuels.
BTW, here in Vermont we’re fortunate to get the majority of our power from Vermont Yankee (a nuke) and Quebec Hydro. My somewhat rosy assumption is that the electricity we DON’T use from these sources goes to someone else and displaces fossil fuel, some of which will certainly be domestic coal even though I’d prefer to displace Middle Eastern oil.
However, there is a way to be sure of displacing oil which is probably coming from Venezuela. That’s step two when we switch from oil heat to geothermal. The compressor in a geothermal system is electrical but uses only a quarter of the electricity that radiant electric heat requires. Still that would be enough electric use where we live to tip us into punitive excess-consumption rates – but the rate doesn’t matter if you generate as much power as you use over the course of a year.
Soon hope to be able to buy a car that plugs in – that’ll make it a solar car indirectly.
We’re trying to be early adopters of the much more electric economy which is coming. And don’t like sending money where it goes when you import oil (and think it may also be useful to use less fossil fuel).
Our photovoltaic system was installed by Dave Palumbo at Independent Power LLC.