All 3rd party solar systems (like the one that came with my house) are engineered to not generate electricity if there is no line power detected. This is to protect backfeed to the grid which could harm linesman trying to repair the grid.
When you have a Tesla Powerwall and Gateway, you can operate solar off the grid... but if your powerwall fully discharges, the solar is engineered not to turn on and charge the battery.
So my feature request is for Tesla to implement a setting where you can specify “when battery gets to X%, shut off powerwall discharge. Then when the sun is up again, turn on powerwall discharge to allow solar panels to generate and charge the battery. If charging does not commence after 10 minutes (too cloudy a day to charge) then shutdown powerwall discharge again until for an hour and try again... or get really smart by tying into weather predictions to see if cloudy is expected for a week. And don’t bother.
Either way, there needs to be more control over this Backup mode.