Windmills a great source of energy

While Solar Energy is great in the day time it can't produce power in the dark. However there are other green energy options such as rooftop mounted wind turbines that might be worth a look especially if you live in an area that is breezy or windy.

Helix Wind


WindTerra


UrbanGreenEnergy


Windspire

Yes they also have an Apple iPhone app called Windspire Me that you can download for free!

Rooftop Wind Power, LLC


Building Turbines