One thought that comes to mind is that household power outages are usually a result of a downed power-line, blown transformer, or similar. Your connection to th

One thought that comes to mind is that household power outages are usually a result of a downed power-line, blown transformer, or similar. Your connection to the grid is lost, but the grid still has plenty of power. In that case, you wouldn't put power back into the grid b/c your connection has been broken. You use the battery for your own power instead.