On our small scale effort, the generated electric would be stored in batteries ready for use when the power fails (often)We wouldn't need to use too many batteries as we are only talking about a need for up to a few hours at a time. One side of our roof faces due south, so would accommodate some small panels quite well.
As an aside, at work we got permission to erect a rather large wind turbine, however, after looking more into the figures, it wouldn't have been cost effective to go ahead with it. We are looking at pv panels though, which produce electric even when it is cloudy (not as much, but enough to be worth while from a PR, feed in tariff point of view) It would certainly help to drop our violently expensive electric bills.
I must find out today if we are going ahead with the plan, it seems to have gone a bit quiet on the news front.......