The device detects that and prevents back feeding. So in case of a power outage it completely shuts itself down.
So when the power goes out it no longer powers your fridge or whatever else you need powered. But it's easy enough to unplug the fridge from the wall and directly into the battery.
alt Hacker News
So when the power goes out it no longer powers your fridge or whatever else you need powered. But it's easy enough to unplug the fridge from the wall and directly into the battery.