The battery backup load center is where the loads you want to run—with or without utility power—are connected. Commonly, only the critical loads are placed in this panel. Many people want to back up all their loads, but most don’t have the energy-efficiency practices and knowledge of their energy use to run an entire home without the grid present. If not managed properly, loads would quickly deplete the batteries, eventually causing the system to shut down. For those who want whole-house backup in the event of a utility outage, an option is to incorporate an engine generator into the system (which also must have a listed and properly installed transfer switch to avoid islanding).
