I'm talking wind and solar here. Solar stops every day when the sun goes down. Wind stops when the wind stops blowing, something that happens a lot around here. Both solar and wind only work when the utilities are forced by law to pay the producers top rates for any juice they may generate, when the sun is up or the wind is blowing. When the sun goes down, or the wind stops blowing, the utility has to have enough real power plants to carry the entire electrical load on their system.
The major cost to the utility is paying off the bonds used to build the power plant in the first place. Consider a new nuclear plant. Those cost about $6 billion to construct. The utility has to float $6 billion in 20 year bonds. Suppose the interest rate is 6%. That means the utility has to make $480 million a year debt service payments on their shiny new plant. That's a lot of money. And they have to make debt payments whether to plant is running or not.
A plant like that will produce a gigawatt of electricity, which can be sold for 8 cents a kilowatt hour. Which works out to $ 700,800,000 a year income. So, assuming the plant runs 24/7, and debt service is paid, the plant owners have only $220,800,000 per year to pay all other costs, labor, maintenance, fuel rod changes, compliance with government paperwork, everything. In short, the debt service is the major cost of producing electricity. And debt service has to be paid whether the plant is running or not. Harry Homeowner's generation may save a little fuel, but that's chicken feed compared to the debt service.
So when Harry Homeowner puts his solar cells on the grid, and gets paid top dollar by the utility, he doesn't save the utility any money. He doesn't reduce the major cost, debt service by so much as a nickel. In fact, he costs the utility. Which raises my electric bill. Which is too damn high already. Which is why New Hampshire has a cap on the number of home alternate energy "net metering" permits allowed.
NHPR was on this the other morning. Most of the net metering permits have been issued. Which means new alternate energy installations won't get paid by the utility. Which means they are pure money losers to Harry Homeowner. So the alternate energy companies are lobbying the legislature to raise the net metering cap. Do that enough and you can drive more industry out of the state.