That is much higher than I would have expected. Good news. What are they using to charge the batteries though? I wonder if it's offpeak renewables or mostly natural gas?
Daytime solar, in the summer especially. Power demand yesterday was negative from 11:30 to 3:30, for instance, meaning batteries can charge for free to absorb excess solar generation during those hours.
If you scroll to the "Supply trend" graph you can see when the batteries were charging and how electricity was being generated at that time.
It's the renewables during the day while the sun is shining.