To provide a safe electricity storage system having good heat dissipation efficiency.

The electricity storage system 10 is configured so that a plurality of capacitor cells 151 are connected in series, and charging current to be applied to each of the capacitor cells is controlled by a corresponding opening/closing device 184. In this system, the plurality of capacitor cells are housed in a container 100, the opening/closing device 184 are each arranged on the capacitor cells, a lid 120 made of an electrically insulating material is attached on a container opening 101, a heat dissipating member 136 is arranged on an opening window 134 formed on the lid, the dissipating member thermally transmissively is brought into contact with the opening/closing element so that the heat generated in the opening/closing element can transmit to the heat dissipating member, and the heat dissipating member exposed from the opening window of the lid is covered with an insulating material. According to the power accumulating system, the heat generated in the opening/closing element is efficiently dissipated to the outside through the heat dissipating member. In addition, in the heat dissipating member, the upper part is covered with the insulating member and the side surface is covered with the lid. With this configuration, if a system operator touches the lid, the dissipating member is free from direct touch and a sufficient distance can be ensured, and safety can be maintained.

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