If you have solar, your Powerwall can recharge from your solar system to run your home from solar and Powerwall even when the grid is down. A traditional solar system without a Powerwall does not function during a grid outage.
If more solar energy is produced than can be used or stored during an outage, Powerwall will turn off the solar system and turn it back on when the energy can be used again. Read more about how Powerwall manages solar production during an outage.
If Powerwall cannot charge at its expected rate, it will signal your solar inverter to reduce or turn off to protect your home from the excessive power produced. This typically occurs when Powerwall is approaching 100% charge. Once Powerwall has the ability to accept power again, your solar inverter will be signaled to produce and will re-start after the qualification period (typically 5 minutes) required by your local requirements.