[XorNot]

The comparison you're drawing though is still hyper-optimized to a specific use-case: a marginal peaking plant i.e. an infrequently used one with a very low required capacity factor (and also presumably operating right at the peak of wholesale pricing on the daily cycle).

But that's a utility being injected into a grid which already has widespread stored-fuel powerplants. I'm not contesting batteries work under some circumstances, I'm contesting whether they actually work when they are doing more then displacing load-handling at the edge. The grid runs 24/7: there's a massive difference between running batteries for 2 hours, and then recharging because you can buy power any time of the day you want, versus their being near zero dispatchable generation on the grid.

Because a gas generator is more then happy to sell you power and run a little longer to do so at any time of day. If that gas generator doesn't exist though, then once your battery is empty it's empty until the renewables pick back up. And that's the answer I'm still not seeing - the question isn't "can you optimize the grid" the question is "can you eliminate stored-fuel power plants entirely". It's fairly obvious that batteries can help in some circumstances given that gas plants have start up times in the tens of minutes, and power prices going negative is bad for them.

EDIT: Basically, are we actually displacing any fossil fuels off the grid, or just optimizing it's expansion - given that an infrequently used peaker plant can become a frequently used peaker plant quite easily, but a solar farm can't do the same.