Google has launched a program called Project Sunroof (Website) where homeowners can see what sort of potential their house has to generate solar power. Google does this by taking information from their Google Maps database and translating it into maps that analyze hot spots and the movement of the sun.
Project Sunroof users simply type in their address to receive illustrations of how many solar panels can be installed on their home and how much they would save if they maximized their solar installation. Sunroof will also point you in the direction of your nearest solar panel installation experts.
The program is currently only available in Boston, San Francisco Bay, and Fresno. There is currently no public information regarding when the program will expand.