A fuel cell system (100, 300, 400), comprising: a first power source comprising a first fuel cell assembly (102, 302, 402) operative to provide electrical power to a load (106, 306, 406); a second power source comprising a second fuel cell assembly (104, 304, 404) operative to provide electrical power to the load; and a fuel cell discharge controller (108, 308, 408) communicatively coupled to the first power source by a first switch or a first power electronics converter and to the second power source by a second switch or a second power electronics converter and operative to reduce a type of degradation of the first or second fuel cell assembly, by alternating power to the load between the first fuel cell assembly when the controller closes the first switch or energizes the first converter, and the second fuel cell assembly when the controller closes the second switch or energizes the second converter, characterized in that said type of degradation relates to a damage of the first or second fuel cell assembly including a structural deformation thereof, and in that the controller is provided with a fuel cell impedance degradation map for each of the first and second fuel assemblies and is able to: - calculate, by means of said fuel cell impedance degradation map and in response to a measured degradation variable (V1 or V2, I1 or I2) of the active first or second fuel cell assembly inputted to the controller, an impedance value of this active fuel cell assembly, said measured degradation variable being selected from the internal temperature, time of discharge, discharge current (I1 or I2) and output voltage (V1 or V2) of the active fuel cell assembly, and - determine whether to deactivate or not the active fuel cell assembly, by a comparison of said calculated impedance value with an impedance degradation criterion set to be a threshold or variance from the initial impedance value of the fuel cell assembly so that the controller provided with said fuel cell impedance degradation map reduces the degradation of the active first or second fuel cell assembly in case said calculated impedance value is outside said impedance degradation criterion, by deactivating this active assembly and activating the other one. a first power source comprising a first fuel cell assembly (102, 302, 402) operative to provide electrical power to a load (106, 306, 406); a second power source comprising a second fuel cell assembly (104, 304, 404) operative to provide electrical power to the load; and a fuel cell discharge controller (108, 308, 408) communicatively coupled to the first power source by a first switch or a first power electronics converter and to the second power source by a second switch or a second power electronics converter and operative to reduce a type of degradation of the first or second fuel cell assembly, by alternating power to the load between the first fuel cell assembly when the controller closes the first switch or energizes the first converter, and the second fuel cell assembly when the controller closes the second switch or energizes the second converter, - calculate, by means of said fuel cell impedance degradation map and in response to a measured degradation variable (V1 or V2, I1 or I2) of the active first or second fuel cell assembly inputted to the controller, an impedance value of this active fuel cell assembly, said measured degradation variable being selected from the internal temperature, time of discharge, discharge current (I1 or I2) and output voltage (V1 or V2) of the active fuel cell assembly, and - determine whether to deactivate or not the active fuel cell assembly, by a comparison of said calculated impedance value with an impedance degradation criterion set to be a threshold or variance from the initial impedance value of the fuel cell assembly