Amazing what California can achieve when they don't have to deal with constant cease-and-desist lawsuits, eminent domain battles, environmental review challenges, etc (crying in high speed rail)
Everything has a big upfront Capex. However you finance it and because renewables are cheap fuel they come out cheap in the long run.
A large part of the Capex of renewables is land costs - which are high, but once you have the land you keep it. This cost is generally all financed as part of the initial build, so in 30 years everything is paid for - but you have to finance to replace only the renewables while keeping the land and so the second round is a lot cheaper.
Including the cost of the batteries to make it stable over the day? Would need a source for that. My understanding is it comparable at best, but certainly not "much cheaper".
As someone who isn't in California, it's understandable that you might think this. It is, fortunately, wrong.
The biggest driver of costs of electricity in CA are (1) paying for damages caused by grid-initiated wildfires, and (2) paying to upgrade the grid to prevent future cases of (1).
This information comes directly from the government who approves rate increases for regulated utilities, and who has to publish their spending. PG&E, the primary power company, is also a public company and their financials are therefore public.
Rooftop solar specifically (and not general grid-scale renewables) do shift the cost balance of fixed-cost infra and consumption based usage, but the wildfire issues dwarf this.
62% is pretty respectable for the size of California (same electricity consumption as Spain). I did not know this.