Wendy Koch

USA TODAY

As environmental groups gear up for their first "put solar on it" national campaign, an online platform made its debut Tuesday that allows people to nominate local buildings throughout the United States for rooftop solar panels.

The new tool by Mosaic, a company that crowdsources funding for solar projects, allows users to click their "support" for any of 300,000 non-profit buildings — mostly churches, schools, libraries, museums. For every 50 clicks in a building's favor, Mosaic will donate $100 to the solar installation.

"This is a way for everyone in the country to contribute to solar in their communities," says Billy Parish, founder of Oakland, Calif.-based Mosaic. His platform, Mosaic Places, launches in advance of the first National Solar Day of Action on Saturday, the longest day of the year, when a coalition of 32 environmental groups plan grassroots events to promote solar power.

As plunging panel prices boost growth in the U.S. solar industry, the tool allows individuals and community groups to rally support for local projects without spending any of their own money. Mosaic, a Kickstarter-like company for solar power, has set aside $2 million for its donations and if more is needed, can tap revenue it collects on homeowner installations.

In March, Mosaic expanded its initial portfolio, which offered a fixed 4.5% annual return to people in New York and California who invested at least $25 in commercial projects, to homeowners wanting to finance rooftop solar arrays. It lends homeowners money for their projects and collects small fees from both the loan and the installers.

"Not every place should have solar but many should," says Parrish, who dropped out of Yale University after his sophomore year — a decade ago — so he could launch the youth organization Energy Action Coalition to spur clean energy solutions to climate change.

Mosaic, which launched in Jan. 2013, has since crowdsourced financing for 20 projects with a combined capacity of 18 megawatts, including investments from 456 people for a 2,244-panel solar system on Pinnacle Charter School in Colorado. It received a $2 million development grant in 2012 from the U.S. Department of Energy.

The debut of Mosaic Places came on the same day that SolarCity Corporation, the dominant U.S. installer of residential solar panels led by entrepreneur Elon Musk announced it will acquire solar panel maker Silevo to expand its capacity.

SolarCity, which allows homeowners to lease their rooftop solar arrays, plans to build a factory in upstate New York so it can ensure a steady supply of efficient, cost-effective panels.

Last year, the U.S. solar market expanded 41% and provided the second-largest source of new electricity capacity — after natural gas, according to a report in March by GTM Research and the Solar Electric Utilities Industry. In the first quarter this year, they reported that the capacity of new residential installations exceeded that of the commercial market for the first time.