This business would only be possible in legislations that already have a free energy market and would, in the long run, benefit the environment, by encouraging investments in renewable energy.
Let's name an hypothetical company operating this business 'Bitenergy'.
There are countries that have a Feed-In tariff See http://en.wikipedia.org/wiki/Feed-in_Tariff
allowing users with power productions abilities to sell the energy they produce in excess and do not use.
Typically users that benefit from this kind of program are those who have a solar panels array at home or wind generator.
The business model is basically the following :
Users with excess power sell said power (measured in kW/h or whatever) to Bitenergy for bitcoins at a given kW/h/btc conversion rate.
Bitenergy measures power it buys with a (supplied by Bitenergy ) tamper-proof wall power meter, at the users site.
Bitenergy re-sell power to any entity for a profit.