> My state proposed a grid battery solution that would have provided power for the entire state for up to 1-2 days IIRC. They didn’t approve it, but the budget wasn’t astronomical. I honestly wonder if the worry about off hours use is a little overblown.

Which state?

Currently, the production scale battery tech that's available (LiIon, LFP), isn't really cost effective for multi-day backup. It's used for very short term (second to hour) and expensive demand response services (substituting for traditional natural gas peaker plants).

The cost/kWh needs to be about an order of magnitude lower to make economic sense for multi-day backup. It's coming, however. There are several contender technologies: metal air, flow, and sodium ion. All of those have much better cost and safety characteristics than Li-ion, while trading off the energy density (which doesn't matter in grid scale stationary storage).