Nah, you can buy retail packs for less than $300/kwh now, I installed some recently. Commercial installs in China are reportedly hitting like $60 installed.

Also, 4 hours is the target Jigar Shah talks about for getting solar to a load factor roughly equal to most thermal plants.

Also, I believe that’s 4 hours on the nameplate of the variable generation, not 4 hours on the entire grid load. People generally aren’t advocating for going fully variable generation.