There's still a very long way to go !
There's still a very long way to go !
For example, if you look at the energy production across PJM from two days ago: https://cdn.bsky.app/img/feed_fullsize/plain/did:plc:hiovtnl...
(Using that b/c I run the bot and it's data I'm very familiar with. You can see similar patterns in CAISO but they've already got so much solar it's a little more messy/duck-curved by all of the behind-the-meter solar.)
You can see hydro coming online from roughly 16:00 - 23:00. There's still a big gas peak that we'd need a lot of storage to shave, and you're right that it's a long way to go before we do that, but it's not quite as bad as "we need enough battery to satisfy 100% peak demand".
But, like with UPS, 96 seconds is ample time to let delicate systems glide to a standstill or to start the diesel generator.