Solar panels are a huge investment, so something like Project Sunroof that can tell you if they're a good fit for your location is extremely useful. The good news is, the initiative is expanding to more locations across the US. Now, if you have a house in select metro areas in Arizona, California, Colorado, Connecticut, Massachusetts, New York, New Jersey, Nevada and North Carolina, you can try plugging in your address on the tool and check if it covers your location. If it does, you'll get an assessment of how many hours of usable sunlight you can get per year, how much of your roofspace can can be covered by solar panels and how much money you can save by getting a solar installation.
Project Sunroof uses the same visuals as Google Earth, and according to the Google Green blog, it looks at the orientation of your roof, the surrounding trees and buildings, as well as local weather patterns to make its assessment. You can try out Project Sunroof on its website -- if you live outside its covered areas just click "Try a Demo" to see how it works.