The state assembly and senate passed final versions of the Clean Energy and Pollution Reduction Act on 11 September. Governor Jerry Brown, a Democrat who backs the law, is expected to sign it into law.
The state currently gets about 30% of its electricity from renewable energy.
Under the measure, electricity providers must source 40% of their retail sales from renewables — such as wind and solar — by 2024, 45% by 2027 and 50% by 2030.
At least 90% of the sales must come from projects within California or from those that are directly connected to the state grid.
But the remainder can be met with unbundled renewable energy credits linked to generation from anywhere in western states.
The new renewable portfolio standard is the most aggressive among those in large US states and is expected to inspire others to follow suit.
California recorded the slowest wind speeds in 47 years in the first quarter of 2015, according to Finnish weather monitoring firm Vaisala.