"A few will plug them into their power walls, which are charged from solar. Lots of roofs in CA have solar."
- Empirical
Mostly not true - Almost all homeowners with Solar panels are tied to the grid. They can't use their panels, even if they have a battery, during a grid shutdown. It's a mandatory safety law as long as you are tied to the grid.
On the other hand, I know Tesla owners who have back up Diesel and or propane powered generators so when the grid is shut down, it switches over to the diesel or propane fueled generator to charge their EVs
Steve
If Tesla's Solar powered super chargers are attached to the grid then they are shut down during a grid shutdown. If not, then they can only be used at night as long as their battery lasts.
I would be surprised if they are not tied to the grid and a battery, so as to generate power back to offset the cost of being able to charge EVs at lower night rates.
I don't know either way - would be interested to find out.