Since its launch in August, Google's informative solar panel initiative Project Sunroof has only been available in the San Fransisco Bay, Fresno, and Boston. Today its footprint has been dramatically expanded, bringing the service to metro areas in the nine most active solar states: California, Massachusetts, Arizona, Connecticut, Colorado, New York, New Jersey, Nevada, and North Carolina.

Project Sunroof utilizes Google Maps data, shade from buildings and trees, and local weather patterns to give homeowners a detailed breakdown of the potential savings of installing solar panels on their homes. Going solar isn't a decision many homeowners take lightly, given the price tag routinely can exceed $20,000 to purchase and install the panels. But that cost can be recouped if your home is properly positioned to take full advantage of the Sun's energy.

• [Editor:tianyawei]