A system for monitoring a plurality of capacitor cells connected in series in a capacitor module which are used as electrical energy stores in an energy storage device and which can be charged in same by a charge current flowing through all the capacitor cells or discharged by a discharge current. The system includes a measuring unit which can determine the voltages applied to the individual capacitor cells by measuring voltages, an evaluation unit which sets a nominal voltage for the capacitor cells, and at least one discharge branch connectable to each capacitor cell and controllable by a discharge control unit which discharges a respective capacitor cell onto said discharge branch depending upon the set nominal voltage and the applied voltage.