This is likely it, though I don't know the particulars of this grid. In most grids, there's a small amount of super profitable frequency regulation to be performed. However, there's very limited capacity needed for that. Doing energy arbitrage over time is much more difficult to make profitable, usually. A huge amount of new solar and wind in the US will be built with batteries attached in the next five years, because it's easier to make energy arbitrage work when you're an energy producer (and also make the tax credits for storage work, which typically require that the batter is only charged from zero carbon electricity).

I remember there was an analysis somewhere that suggested we need batteries at 20$/kwh to achieve 100% renewable production. But we only need 150 $/kwh to achieve 80% renewable. So there are probably low hanging fruit to get right now. Hopefully all this extra production will drive battery prices down.

Nah, the state’s broke