We started scaling batteries after solar (because the technology reached the point where they were profitable after solar)... but they're being installed at scale now, and at a rapdily increasing rate.

Batteries provided 42.8% of California's power at 7pm a few days ago (which came across my social media feed as a new record) [1]. And it wasn't a particularly short peak, they stayed above 20% of the power for 3 hours and 40 minutes. It's a non-trivial amount of dispatchable power.

[1] https://www.gridstatus.io/charts/fuel-mix?iso=caiso&date=202...

Batteries are a form of dispatchable power not "base load". There is no "base load" requirement. Base load is simply a marketing term for power production that cannot (economically) follow the demand curve and therefore must be supplemented by a form of dispatchable power, like gas peaker plants, or batteries. "Base load" power is quite similar to solar in that regard. The term makes sense if you have a cheap high-capitol low running-cost source of power (like nuclear was supposed to be, though it failed on the cheap front) where you install as much of it as you can use constantly and then you follow the demand curve with a different source of more expensive dispatchable power. That's not the reality we find ourselves in unless you happen to live near hydro.