That might be useful for aircraft, but not cars or the grid. Batteries are already cost competitive with peaking power plants and prices just keep dropping.
Run some numbers and you find batteries are surprisingly cheap at grid scale. Grid solar is already tied into the grid and does DC>AC conversion anyway as part of it’s 2c/kWh pricing. So, rather than AC>DC>AC>DC you can just use solar panel’s AC power directly. Which means your just adding minimal cabling, batteries, some electronics, and a basic box for weather protection. So, ~100,000$ for 200kWh of storage x ~5,000 cycles that’s 10c/kWh for storage + (2c/kWh solar / 90% efficiency) = ~12.2c/kWh.
Granted that ignoring some real world costs like interest payments, but battery costs are also dropping so it’s a reasonable ballpark. Especially vs a theoretical system that’s never been scaled.
PS: By comparison if your at 50% efficiency to chemical storage and world record 63% thermal efficiency at combustion that’s 2 /.5 /.63 = ~6.3/kWh just for electricity plus the cost of your combined cycle gas turbine and chemical plant.
