Google's Project Sunroof helps determine the best solar plan for homeowners based off high-res aerial imagery that determines the amount of sunlight hitting a roof each year (and what kind of installation will optimize that), as well as current pricing data, federal and state tax credits, utility rebates, renewable energy credits, and net metering to calculate a financial estimate.

When Project Sunroof launched in August 2015, the tool's capabilities were limited to San Francisco, Fresno, and Boston. In January, Google expanded the program to 20 metros in states where the solar industry is most active, like Colorado, Connecticut, Arizona, and Massachusetts.

With the latest expansion in April, Project Sunroof can now analyze and calculate solar plans for "roughly 43 million rooftops" in 42 states. Currently, the tool cannot provide information to potential consumers in Alaska, the District of Columbia, Hawaii, Mississippi, Rhode Island, South Dakota, Tennessee, and Texas, but Google hopes to expand coverage to all 50 states before the end of the year.

Project Sunroof is valuable for solar companies as well, as it serves as a lead generator and refers potential customers to solar providers in their area. The companies referred by Project Solar have paid to join the platform however, and they must bid to receive customer referrals.

"Project Sunroof currently hosts a mix of solar companies, including major players like SunPower, local installers like Verengo Solar and new players like Pick My Solar. Interested customers can choose to share their contact information with selected providers on the Sunroof platform or contact them directly."

Outside of lead generation, Google hopes to expand Project Sunroof's services in the future by making it possible for their solar partners to track other valuable information, like utility rate changes.

The major challenge for Google will be to make the public more aware of Project Sunroof, and expand the pool of potential customers.

In an interview with Greentech Media's Julia Pyper, Nicole Lombardo, head of business development and partnerships at Project Sunroof, highlights two ways the project hopes to serve solar companies.

“First and foremost, this is about how Google can catalyze the rooftop solar market,” said Lombardo, speaking at GTM's Solar Summit. “That was some of the first feedback we got from developers: volume, volume, volume -- we need more qualified homeowners.”

“The second piece of feedback was [the question of whether Google can] help us expedite the process of qualifying [potential solar customers],” she added. “That’s where some of the new imagery that we have and being able to calculate whether or not they have enough roof space helps simplify a couple of steps.”

Read more about Project Sunroof's longterm goals and challenges from Greentech Media >>