Energy storage module and system

The present invention relates to an energy storage module (200), an energy storage system (300) comprising such modules and to a method for manufacturing an energy storage system. The energy storage module comprises an energy storage cell unit (204) and a cooling plate unit (202) which are kept in thermal contact with each other by a first retaining element (210) having a through-hole (212) and two deformed end portions (214, 216). One of the end portions are deformed after the first retaining element has been arranged through the energy storage cell unit and the cooling plate unit. Two or more modules may be stacked together to form an energy storage system. The modules are then held together by a second retaining element (302) arranged through the through-hole of the first retaining element.