Battery Energy Storage System (BESS)

A battery energy storage system (BESS) is a battery, its power conversion system, and its controls, installed to store electricity and deliver it back to a site or the grid on command.

A BESS has four layers. The cells and their battery management system store the energy and protect themselves. The power conversion system moves power between the DC battery and the AC grid. The energy management system decides when and how much to charge or discharge. A power plant controller, where one is required, holds the plant inside its grid code at the point of interconnection. The same system can earn from several of these at once: demand charge reduction, arbitrage, frequency regulation, and backup.

Also called: Battery storage, Energy storage system, ESS