An energy storage system (1) is provided. The energy storage system (1) includes a plurality of battery clusters (11), a plurality of power regulators (12), a transformer (13), and a central controller (14). The plurality of power regulators (12) is configured to control charging and discharging of the plurality of battery clusters (11). Each power regulator (12) is electrically coupled to corresponding two, at most, of the plurality of battery clusters (11). A first terminal of the transformer (13) is electrically coupled to the plurality of power regulators (12), and a second terminal of the transformer (13) is electrically coupled to the power grid (2). The central controller (14) is coupled to the plurality of power regulators (12) and the plurality of battery clusters (11) for controlling the plurality of power regulators (12) and the plurality of battery clusters (11). The central controller (14) is in communication with the plurality of power regulators (12) through optical fibers, and a data transmission rate of the optical fibers is greater than IMbit/s.