Energy Management System (EMS)

An energy management system (EMS) is the software that decides when a battery charges, when it discharges, and how much power it moves.

A storage EMS makes that decision every few seconds from prices, tariffs, forecasts, grid signals, site meters, and the limits the battery reports, then sends a power setpoint to the inverters. It sits above the battery management system, which protects the cells, and the power conversion system, which executes the command. It is not a BMS, not SCADA, and not a power plant controller, although one vendor may deliver all four. A storage EMS runs on hardware at the site so it keeps operating when the wide area link drops.

Also called: Storage EMS, Battery EMS, Energy storage management system, BESS EMS