That works if you’re home, but what happens if you’re traveling when the grid outage happens?In a grid out situation you will always need to pay close attention to your home's energy usage and manually shed loads as necessary. Even if the powerwalls are fully charged if you exceed the rated power draw of the powerwalls and whatever solar you are producing they will shutdown.
That being said, I’ve decided to add a third Powerwall to our system, so in theory I should never encounter this issue, as long as everything works as designed.