A method for operating a fuel cell system includes drawing a base level DC electric energy from a first fuel cell of a first type to a combined DC bus, measuring a DC voltage at the combined DC bus, determining whether the DC voltage at the combined DC bus...

Provides a solid oxide fuel cell with which product life can be extended while a practical output power is maintained. The present invention is a solid oxide fuel cell, having a fuel cell module (2), a fuel supply device (38), an oxidant gas supply device ...