Depends. Are we talking battery needs for the Southwest? Yes. Other places that don't have a relatively constant solar output and more variable seasons? No. But this is one of the many reasons the situation is substantially more complicated than the general conversation.
> Other places that don't have a relatively constant solar output and more variable seasons? No.
How big of a problem is this really, though? We could run more HVDC lines (as we already have in some places), such that sunny states provide power to northern states in the winter.
I don't actually know the answer. I do know that there isn't a singular grid in the US though so there are some complications. From my limited understanding the Texas power problem wouldn't have been solved if ERCOT was connected to the western or eastern grids. We're also talking about big losses if we're transmitting electricity across the country. There's also political issues as well as security issues (don't put all your eggs in one basket and don't putt all your baskets in the same place).