California Takes Big Step to Require Solar on New Homes

California took a major step Wednesday toward becoming the first state to require solar panels on nearly all new homes, the latest sign of how renewable energy is gaining ground in the U.S.

The California Energy Commission voted 5-0 to approve a mandate that residential buildings up to three stories high, including single-family homes and condos, be built with solar installations starting in 2020.

The commission estimates that the move, along with other energy-efficiency requirements, would add $9,500 to the average cost of building a home in California. The state is already one of the most expensive housing markets in the country, with a median price of nearly $565,000 for a single-family home, according to the California Association of Realtors.

Still, the change appears to have broad support from home builders as well as California leaders and solar advocates.

Nationally, solar power makes up less than 2% of U.S. electricity output, according to the U.S. Energy Information Administration. But it is rising because of large solar farms as well as rooftop solar arrays on homes and businesses.

Renewable-energy technologies, in general, are gaining market share in the power sector as their costs go down, along with natural gas, which has become plentiful and cheap due to fracking.

California has often been a bellwether on U.S. environmental and energy efficiency issues, with states such as Massachusetts, Minnesota and New York sometimes following its lead. But some experts were skeptical that California’s solar-panel mandate would widely influence policies elsewhere.

Steve Kalland, executive director of the North Carolina Clean Energy Technology Center at North Carolina State University, doesn’t see his state—the No. 2 solar market in the U.S. behind California—adopting a similar mandate soon.

“It is a pretty big stretch to imagine certainly any Southeastern state following suit in the near term, but the technology is getting cheaper and cheaper and the public is starting to clamor for it,” he said. “In North Carolina, the market is much more oriented toward larger scale solar farms.”