Under net billing — yes, for almost everyone. Export credits were cut ~75%, so selling your excess solar to the grid is a losing trade most of the year. A battery stores your own daytime power for your own nighttime use, which is now the whole game. Without one, you'd need to size solar to only ~60-70% of usage and accept a permanent utility bill.
Batteries also unlock the stackable money: SDCP's $3,000-$6,000 rebate, VPP yearly payments, and those $1-$3.50/kWh August-September export credits. In 2026 California, the battery isn't the add-on. It's the strategy.