Fuel cell system

A fuel cell system (10) is provided with a power control unit (53) that, during an external power supply process in which power is supplied to an external load (LD), controls power generation by an FC stack such that power is generated at a predetermined power generation efficiency, and charges a battery (41) by supplying the remaining power, which is not consumed, from among the power generated by the FC stack to the battery (41). The power control unit (53) stops the power generation of the FC stack and controls the output of the battery (41) such that the power of the battery (41) is supplied to the external load LD when the charging rate of the battery (41) reaches a first prescribed value or more during the external power supply process, and restarts the power generation of the FC stack when the charging rate drops to a second prescribed value or less that is smaller than the first prescribed value. 本发明提供一种燃料电池系统10，具备电力控制部(53)，该电力控制部(53)在处于向外部负载LD供给电力的外部供电过程中时，控制FC堆的发电使得以规定的发电效率发电，将FC堆的发电电力中未消耗的剩余电力向电池(4