This data comes via Mark Z. Jacobson, a Stanford University professor of civil and environmental engineering.
While California has hit 100% renewable energy before, for brief moments on exceptionally sunny days, this is the first time the state has sustained that success over an extended period. As Jacobson noted, there was even a portion of a recent day when wind, water, solar, and geothermal power combined to reach 109% of the state’s electricity demand, with anything unused going to battery storage.
Though California does still rely on dirty energy as well as clean energy to power its grid, Jacobson predicted that the state will reach its goal of being permanently 100% WindWaterSolar by 2035.
I feel like projects like Nova Power Bank are really important for the further development of grid sustainability. California already had large scale solar projects decades ago and AFAIK catches on with wind as well, but to combine both properly, large scale battery plants come in handy and further demand might decrease their costs.