A vast majority of Californians who decide to go solar decide not to own their own systems, according to a report from SunRun.

SunRun, which owns, maintains and operates third-party residential solar installations, found that 75 percent of Californians who decide to install residential solar today opt for third-party-operated systems.

Since 2007, Californians have invested $1 billion in third-party-owned solar installations.

“What that means is that more people are able to afford to go solar,” said Susan Wise, spokeswoman for SunRun.

Third-party-owned systems allow customers to install solar one their homes with no upfront costs. They sign a power-purchase contract and agree to buy the power their rooftop installations generate at a fixed price.

“More people are becoming aware that this option exists,” Wise said. “A lot of people who have wanted to go solar can actually do it now because they don’t have to spend thousands of dollars upfront.”

Wise said the fastest growing areas for solar installations, which were dominated by third-party programs, were median income zip codes, which Wise said speaks to the model’s success in making solar more accessible.

The number of projects in middle income markets (with average household incomes between $50,000 and $100,000) increased 445 percent between 2007 and 2012, according to the release. It’s the fastest-growing sector.

SunRun launched its model in 2007 and installs more than $1.5 million in solar equipment daily, according to a release from the company.

The number of California homeowners opting for third-party-owned solar installations in 2012 was 30 times what it was when SunRun started in 2007.

And the growth hasn’t stopped yet. The solar market in California, which is the strongest in the country, has strengthened year after year, with a record number of megawatts installed every year for the last six years. 

“We expect the growth to continue,” Wise said.