We recently had photoelectric panels installed. We have 8 kw. In Germany this is subsidised and we reckon to break even in about 9 years, just by selling it and by own use during the daytime.
Anyway, the point is not to make a profit, but to make our own electricity, to at least feel a bit self-sufficient. So we need a method of storing our nice power until we need it, e.g. to charge an electric car or to heat water.
There are many ways to do this; batteries seemed to me to be the obvious solution but they are extremely expensive, and some of them are fire-risks. Then the solar man suggested compressed air, although this is apparently noisy. Then there's turning water into hydrogen and back again - which sounds like a fire risk to me.
In this erudite circle there is certainly someone who can point me in the right direction; I'm fine with new technology but it has to be
edit: Hmm, environmental impact. I gather our solar panels will now generate more power in their official 20-year lifespan than were used in their manufacture. But this is a different question. But really it's about self-sufficiency - a suspicion that if Germany gets any greener they will start rationing electricity (this has been mentioned, in passing, by the Greens). Also, turning off the nuclear power stations and iffy gas deliverers may well mean the power just goes off on dark nights with no wind.