Black start
The ability of a power source to restart without relying on an external electricity supply. In BESS, this means the system can energise itself and begin supplying power to help restore the grid after a complete or partial blackout, or to establish an internal microgrid providing backup power to critical loads.
In energy storage
Black start-capable BESS requires a grid-forming inverter, as grid-following inverters cannot establish voltage and frequency on a de-energised network. Black start capability is becoming an increasingly common requirement in grid codes, particularly in regions with high renewable penetration and high concentrations of inverter-based resources (IBR). As a function, it complements grid-forming capabilities to strengthen overall grid resilience.