The Energy Commission estimates, however, that homeowners will only see an additional $40 to monthly mortgage payments. It came despite estimates it would raise the up-front cost of a new home by almost $10,000 in one of the most expensive parts of the country.
California has become the first U.S. state to mandate solar panels on new homes and apartment buildings built after 1 January, 2020.
"We can not let Californians be in homes that are essentially the residential equivalent of gas guzzlers", Commissioner David Hochschild said ahead of the vote.
The updated building code also includes stricter efficiency standards on lighting, ventilation, windows, walls and attics for non-residential as well as residential structures.
While the new requirements aim to reduce greenhouse-gas emissions - one of the state's greatest challenges - they may worsen another problem in the short-term: the high cost of housing.More news: Khloe Kardashian, Tristan Thompson 'still together' after cheating scandal
State law already requires that 50% of all electricity comes from non carbon-emitting sources by 2030. Several California cities have already been mandating some solar power in new buildings.
Utilities that objected to the new rate-design "could contend that the introduction of mandated distributed solar sufficiently alters the policy landscape to warrant further review of the compensation levels paid to excess generation", ClearView said in their report, published ahead of the energy commission's decision.
"SEIA appreciates the Commission's efforts to help California take steps toward meeting its Zero Net Energy goals by integrating renewable energy with energy efficiency". But over the past decade, California has averaged less than half of that. At the end of 2017, it had reached about 30 percent, according to the CEC. Governor Jerry Brown is planning a global climate summit this September.
Adding solar panels would boost construction costs by $9,500 for a single-family home but save owners about $19,000 in energy and other expenses over 30 years, the Energy Commission estimated.
Buildings that are shaded or have a roof that is too small to accommodate panels will be among those exempt, California Energy Commission spokeswoman Amber Pasricha Beck said.