In an experiment today, my PoweWall/Gateway setup would not start without Grid Power. Here is the sequence that I followed to do a cold restart of my system that consists of a 125A breaker on my main panel feeding a gateway connected to a backup panel and a generation panel with 9.9 kW of Solar and 2 PW2's: Switched the 0/1 switches on the PW2's from 1 to 0. The PW2's were at 99-100% charge and their green light bar stayed on. Opened the 125A breaker on the main panel. The lights on the Gateway and the PW2's stayed on. Waited about 10 minutes. PW/Gateway lights stayed on, but there was no switch to backup power; the power stayed off. Pushed the "reset" button on the Gateway and held it down for about 10 seconds. All the PW/Gateway lights went off. Waited about 5 minutes. Flipped PW2 switches to On/1. Nothing happened. Waited about 5 minutes. Nothing happened. Closed 125A breaker to feed Gateway/PW system with grid power. PW system restarted. Does this mean that you can't start a PW system without grid power? How do you start an off-grid system? How about an extended grid outage with bad weather and poor solar production where you shut down the PW's with some battery left, then want to restart when the sun shines again?