SolarCity Corp. employees install solar panels on the roof of a home in Kendall Park, N.J. last month. (Michael Nagle/Bloomberg)

Tech giants are really into sun power. Apple is building massive solar farms in California and China. Elon Musk co-founded SolarCity, a company focused on residential solar panel installation, that has garnered a major investment from Google.

And now the search giant is using Google Maps to help people figure out how well solar panels will work for their house.

A new project, dubbed Sunroof, uses Maps data along with information from other databases to estimate how much buying or leasing solar panels could save homeowners on their electricity bills in the coming years — taking into account things such as shade from trees, sun position throughout the year and historical cloud and temperature patterns.

Then the tool provides information about solar providers available near homeowners' addresses.

Not everyone can use it yet: Right now, it works only for people in the San Francisco Bay area, Fresno, and the greater Boston area. But a launch video promises that "pretty soon it will grow to include the whole country and maybe even the whole world."