FUEL CELL SYSTEM AND CONTROL METHOD THEREOF

PROBLEM TO BE SOLVED: To provide a water stand-alone operation type fuel cell system that efficiently collects vapor in exhaust gas of a fuel cell.SOLUTION: A fuel cell system 1 includes a fuel cell 10, a water tank 14 which contains a condensate collected from the vapor in the exhaust gas, a temperature sensor 20 which detects temperature during power generation by the fuel cell 10, a water level sensor 22 which detects the water level of the water tank, a concentration sensor 21 which detects a concentration of oxygen etc., included in the exhaust gas, and a controller 18 as control means. The controller 18 performs increase/decrease control over the amount of air supply and the amount of fuel supply to the fuel cell 10 according to the detected temperature of the temperature sensor 20 and the detected concentration of the concentration sensor 21 when the detected water level of the water level sensor 22 is lower than a predetermined water level. In this case, the amount of air supply is controlled in a decrease direction when the detected temperature is higher than the predetermined temperature, and the amount of fuel supply is controlled in an increase direction when the detected temperature is lower than the predetermined temperature.