My math on this is 400 MW of solar, but with the typical over the day spread. The batteries can either charge or discharge up to 400 MW, but can hold 1600 MWh.
In that the panels and batteries are both at the same site, losses should be reasonable (and might already be built into the number). This balance should let the "combination" run pretty much one deep cycle per day most days:
In KWh:
1,600,000 x 300 x 10 = 4,800,000,000 or 4.8 billion KWh, which works out to $0.21/KWh.
Add in some incentives, plus the possibility to expand on the same site, and it makes a lot of sense, especially in that the power it sells is "peaker" power, not baseline like nuclear.