On Wednesday, the Golden State became the first in the U.S. to require solar panels on almost all new homes. Most new units built after Jan. 1, 2020, will be required to include solar systems as part of the standards adopted by the California Energy Commission. While that’s a boost for the solar industry, critics warned that it will also drive up the cost of buying a house by almost $10,000. Solar shares surged on the decision. Homebuilders fell.

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.”