Backup power mode, called Backup-Only in the Tesla app, reserves 100% of your Powerwall energy to provide seamless power to your home in the event of an outage. Powerwall will charge from the grid (if you don’t have solar) or from your solar system and only discharge during a grid outage.
Backup-Only mode behaves similarly to setting your Powerwall in Self-Powered mode with a 100% backup reserve.
During a power outage, you might consider adjusting some behaviors to extend your use of Powerwall. Read more about life with Powerwall during an extended outage.
How to set up Backup-Only
From the home screen, tap 'Customize.'
Select Backup-Only mode.