An energy storage system, to improve operating efficiency and system reliability that exist when a component in the energy storage system is faulty, and avoid a waste of resources. The energy storage system includes a plurality of energy storage branches, at least one switch unit, and a control circuit. Each of the energy storage branches includes a first bus, a string-level converter, and a battery string that are sequentially connected in series, a plurality of balancing converters, and a shared bus. The battery string includes a plurality of battery units connected in series, and each of the battery units includes one battery pack. The battery pack is connected to an input side of one corresponding balancing converter, and output sides of the plurality of balancing converters are separately connected to the shared bus.