Sineng Electric's 50 MW/100 MWh sodium-ion battery energy storage system (BESS) project in China's Hubei province is the first phase of a larger plan that will eventually reach 100 MW/200 MWh. The initial capacity has already been connected to the grid and can power around 12,000 households for an entire day.
I talked to an energy engineer about it, and I’m pretty sure it’s what he said. Would also make sense when China use it like this.