The US uses over 3 terra watts of power.
...
At night?
The grid has to be sized for the peak load. That is one thing a lot of people don’t understand.
The batteries are for storing the power for when the solar panels are not generating power. There is no way one square mile of batteries could power the US at night. That is absolute crap.
All green energy needs 100% base load backup. That backup is what the batteries are intended replace.
Here’s the fuel mix on the MISO footprint in real time. It will give you some perspective;
https://www.misoenergy.org/MarketsOperations/RealTimeMarketData/Pages/FuelMix.aspx