California has become the first state in the nation to mandate solar panels for all new homes, in a move to cut greenhouse gas emissions that critics say will end up raising home prices in the already expensive market.

In a unanimous 5-0 vote Wednesday, the California Energy Commission approved the policy.

The regulation will require all homes and apartments built after 2020 to have solar panels, adding an average of roughly $10,000 to construction costs for a single-family home. On the flip side, the commission says, the panels could yield much more in energy savings.

Spokeswoman for the Energy Commission Amber Beck told Fox News that under the new standards, new homes would be expected to reduce energy use by more than 50 percent. She argued that the change will lead to savings in the long run.

“For residential homeowners, based on a 30-year mortgage, the Energy Commission estimates that the standards will add about $40 to an average monthly payment, but save consumers $80 on monthly heating, cooling, and lighting bills,” Beck said in a statement. “On average the 2019 standards will increase the cost of constructing a new home by about $9,500 but will save $19,000 in energy and maintenance costs over 30 years.”

Few industry groups outwardly oppose the plan after working for years with the commission to shape the regulations. But Republican legislative leaders said Californians can't afford to pay any more for housing in the state's already expensive market.

"That's just going to drive the cost up and make California, once again, not affordable to live," said Assemblyman Brian Dahle, the chamber's Republican leader.

The solar panel decision is just the latest example of what critics see as the state’s ever-evolving nanny-state policies. California often is at the leading edge of government mandates and bans, having recently prohibited everything from plastic bags to foie gras – and even flirting with phasing out internal combustion engines.

Bill Watt, a homebuilder and design consultant, told The Orange County Register the added solar panel costs, in addition to other building mandates, will make homeownership out of reach for many buyers.

“We’re not building enough housing already,” Watt, former president of the Orange County Building Industry Association, told The OCR. “Why not just pause for a little while, focus on the affordability and housing issues, then circle back?”

Despite the increase in construction costs, the California Building Industry Association generally supports the plan, but expressed a preference to delay the launch.

“[W]e would prefer that this had been put off for a few more years, but the fact is that the California Energy Commission has been working on this, with us, for the past 10 years,” the association’s technical director, Robert Raymer, said in a statement, noting that the group worked with the state’s energy commission to alter the policy. “We know this is coming, we did everything we could to push down compliance costs and increase design flexibility.”

The mandate is the latest win for the solar industry, despite past controversies tied to companies' use of taxpayer funds.

The most notorious example was California company Solyndra, which filed for bankruptcy in 2011. An Energy Department inspector general report in 2015 said the company misrepresented facts in order to secure a $535 million loan guarantee from the federal government. Taxpayer lost most of that money in the deal.

The new California measure would reduce greenhouse gas emissions by 700,000 metric tons over three years, according to the commission. The Energy Commission said this would be equivalent to taking 115,000 cars off the road.

The Associated Press contributed to this report.