California on Wednesday became the first state to require solar panels on all new, single-family homes.

The California Energy Commission voted 5-0 to approve changes to the state’s building code to require single-family homes be equipped with solar panels starting in 2020.

The regulations also apply to new multi-family buildings of three stories or fewer. The new rules don't need the approval of the legislature or the governor.

The Energy Commission estimates that the mandate, with other new energy-efficiency measures, would add $9,500 to the average cost of building a home in California, not a small amount for a state that already has one of the most expensive housing markets in the country.

Buyers of new homes would have monthly mortgage payments rise by an average $40, while their monthly utility bills would drop by $80, the commission projects.

Despite the cost concerns, the change had broad support from home builders, state political leaders, and solar advocates.

Supporters say the proposal will save costs in the long-term and is a key piece of California’s plan to goal to reduce carbon dioxide emissions by 40 percent below 1990 levels by 2030.

A new rate structure the state is implementing next year charges California customers based on when during the day they use electricity. Those with solar power likely would pay less, especially if paired with batteries, which can store excess solar for use when the sun isn’t shining.

The new rule encourages the use of the quickly rising, but expensive, technology because it allows alternative compliance through using energy storage.

About 15 percent to 20 percent of new single-family homes built in the state include solar, according to Bob Raymer, technical director for the California Building Industry Association. Solar power provides almost 16 percent of the state’s electricity.

“California has long sought carbon reductions from electricity supply, once the state’s largest source of carbon emissions,” Timothy Fox, vice president at Clearview Energy Partners, who studies renewable energy, told the Washington Examiner. “Today’s rule signals the state’s progression to tackling the electricity demand side and the state’s other large source of carbon emissions — buildings.”

Fox said he was skeptical other states would move as quickly as California to impose similar rooftop solar requirements, but the state’s action could inspire momentum.

New Jersey, Massachusetts, and the District of Columbia have considered legislation to require new buildings have the ability to be fitted with solar, according to the National Conference of State Legislatures.

“While the finalization of this mandate could spur some proposals from legislators in other green-leaning states (Massachusetts comes first to mind), we are skeptical such proposals would advance at the same fast pace as California’s,” Fox said. “In short, California’s new home solar mandate could be the first data point in a potential, but not necessarily fast-moving national energy policy trend."