The California Building Standards Commission unanimously confirmed the standards during a vote on Wednesday, The Mercury News reported.
Commissioner Kent Sasaki described the new policy as “historic” and a model for the rest of the nation to follow.
“These provisions really are historic and will be a beacon of light for the rest of the country,” he said, according to The Mercury News. “[It’s] the beginning of substantial improvement in how we produce energy and reduce the consumption of fossil fuels.”
The mandate—which was originally approved by the state’s energy commission in May—applies to all houses, condos and apartment buildings up to three stories tall that obtain building permits after Jan. 1, 2020. An exception will apply for homes that are shaded by trees or buildings that have a roof too small to accommodate solar panels.
The new policy could add an estimated $10,000 to the building a single-family home. However, that cost is expected to be offset through reduced monthly energy costs over a solar system’s lifespan, commissioners noted.
Drew Bohan, executive director of the energy commission, said during Wednesday’s session that a homeowner will save $19,000 over the course of a 30-year mortgage by having solar panels, NPR reported.
“With extreme weather events becoming more frequent, there is even greater need for homes that are efficient, reliable and resilient,” Bohan added.
California has 24.3 gigawatts of solar PV capacity and is the country’s undisputed solar champion, with roughly five-times the capacity of second-ranked North Carolina. Approximately 6 million homes in the Golden State are supplied by solar energy.
The world’s fifth largest economy has one of toughest clean energy mandates. In September, Gov. Jerry Brown signed a law that requires 100 percent of the state’s electricity to come from renewable sources by 2045, making it the second state after Hawaii to set such a mandate.