Just so you're aware...
If you have solar but no Powerwalls and the grid goes down, your solar will be useless. Typical inverters shut down as a safety measure if there's a grid outage, that way there's no chance of them trying to backfeed power to the grid while utility personnel are trying to make repairs. On the other hand, if you have both solar and Powerwalls, your solar inverter will keep running during a grid outage (for the most part...there are a few edge cases that aren't really important at this level of discussion), and you can keep your house powered for quite awhile during an extended outage.
Bruce.