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“This is massive,” said Morten Lund, chair of an energy storage initiative at law firm Stoel Rives LLP. “Essentially, this could turn residential solar into an appliance, like a water heater. There has always been a certain inevitability about that outcome, but this is moving faster than most of us thought likely.”

Sunrun Inc., the largest U.S. residential-solar installer, gained as much as 6.4 percent before closing at $9.83 in New York on Wednesday. Tesla Inc. rose as much as 1.7 percent and SunPower Corp. climbed almost 7 percent. KB Home, which has significant exposure to the California market, fell as much as 5.3 percent.

The U.S. had 10.4 gigawatts of residential solar power at the end of last year, up more than sixfold from five years earlier. The industry started slowing in 2017 amid policy changes and efforts by some companies to shift their strategies.

“Adoption of these standards represents a quantum leap in statewide building standards,” Bob Raymer, senior engineer of the California Building Industry Association, said during the meeting before the vote. “You can bet the other 49 states will be watching closely what happens.”

Tesla’s Francesca Wahl, senior associate of business development and policy, was among the company representatives to back the mandate at the meeting Wednesday, and expressed support for provisions that will also promote wider use of energy storage systems.

California’s solar policy will exacerbate another critical issue in the most populous state, where high housing costs are seen as a drag on the economy that also contributes to rising social tensions.