An energy storage module, an energy storage system including such modules, and a method for manufacturing an energy storage system are disclosed. The energy storage module may include an energy storage cell unit and a cooling plate unit which are kept in thermal contact with each other by a first retaining element having a through-hole and two deformed end portions. One of the end portions is 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 may be held together by a second retaining element arranged through the through-hole of the first retaining element.