Solid oxide fuel cell system and method for operating the same

The method involves supplying fuel to an anode side and discharging anode exhaust gas on the anode side. A partial stream of the anode exhaust gas is fed back to anode side as a recirculation gas and remaining partial stream is discharged as exhaust gas. The measuring devices are arranged to measure the volumetric flows of discharged anode exhaust gas and recirculated anode exhaust gas respectively so as to determine the ratio of recirculated exhaust gas with respect to total amount of exhaust gas. An independent claim is included for solid oxide fuel cell.