Google and SolarCity have teamed up to create a $750,000,000 fund to promote affordable residential solar installations. The new fund will cover the upfront cost of solar panel installations for thousands of homeowners in 14 states and the District of Columbia, and make it possible for them to pay less for solar power than they pay for electricity generated by fossil fuels.

“We’re happy to support SolarCity’s mission to help families reduce their carbon footprint and energy costs,” said Sidd Mundra, Renewable Energy Principal at Google. “It’s good for the environment, good for families and also makes good business sense.”

Google has committed $300 million to the new fund—its largest renewable energy investment to date. The new fund is the largest of its kind ever created for residential solar power, and the second such collaboration between the two companies. The new fund is designed for home owners who need help with the down payment they need to obtain a solar system. It will apply to both leased and purchased systems.

The goal of the collaboration between Google and SolarCity is to show homeowners that solar power is not only environmentally friendly, it also costs less than electricity from traditional fossil fuel sources. The myth that solar is much more expensive has been promoted by the fossil fuel industries for decades, just the way self-interested parties promote the myth that climate change is not associated with human activity.

It’s all abut democratizing solar and making it more accessible to middle income families, Jonathan Bass, SolarCity’s vice president of communications, told The Week recently. “It’s an equation with a few variables,” Bass explained.  Those include the local cost of retail electricity, which is higher in some areas of the country than others, and differences in sun exposure in different regions. Differences in state and local financial incentives and building codes also figure into the mix.

With the help of Google, SolarCity plans to reach 25,000 new households and add 500 megawatts in new capacity. That represents a significant increase to their current customer base of 190,000 and 1,000 megawatts of capacity as of the end of 2014.

“If you can lower my overall energy bill — if I pay less for solar than I’m paying for utility power today, with no out of pocket costs up front — that’s something I’d love to do,'” Bass says. “Those are homeowners that really value $20, $40 a month in savings. That can add up to thousands of dollars over the years.”

In other words, the program is designed to say to potential new solar customers, “If you could, why wouldn’t you?” It’s a nothing to lose and everything to gain proposition. In the larger sense, this initiative will go a long way to proving to the world that solar power really is the most economical choice when it comes to providing electrical power for our homes.