A fuel cell system (1) has a plurality of fuel cell modules (11-1n) which are connected so as to form a fuel cell group (10) that has a first and second electric supply connection (101, 102) configured to be connected to an electric load (2); a measuring device (21-2n) which is connected to the fuel cell modules (11-1n) and is designed to measure a load current of each fuel cell module (11-1n); and a controller (20) for detecting a respective operating state of the fuel cell modules (11-1n) using the load current of each fuel cell module measured by the measuring device (21-2n), wherein the controller is connected to the fuel cell modules (11-1n) in order to control the operation of the fuel cell modules (11-1n). The controller (20) is designed to detect whether the operating state of thefuel cell modules (11-1n) is in a respective partial load range (42) of the respective fuel cell module, said partial load range being defined by a lower threshold (421) above a load current of null and an upper threshold (422) below a full load current. The controller (20) is additionally designed to provide a load current (lL) required by the load (2) in a first partial load operation of the load by operating all of the fuel cell modules (11-1n) of the fuel cell group (10) such that all of the fuel cell modules (11-1n) of the fuel cell group (10) are in the respective partial load range (42)of the respective fuel cell module (11-1n).