In accordance with an embodiment, an energy storage system includes energy storage container that a temperature control system, a battery cluster, and a controller. The controller determines a specified temperature of the temperature control system corresponding to a maximum difference between an available capacity of the battery cluster and a power consumption of the temperature control system as a target temperature. The determination of the specified temperature is based on: a correspondence between the available capacity of the battery cluster and a plurality of different specified temperatures in a specified temperature set of the temperature control system, and a correspondence between the power consumption of the temperature control system and the plurality of different specified temperatures in the specified temperature set of the temperature control system. The temperature control system is configured to adjust a temperature inside the energy storage container to the target temperature.