CONTROL METHOD FOR FUEL CELL POWER

A power controlling method for a power supplying system coupled to a load is disclosed. City energy is detected. It is determined whether the city energy corresponds to a first pre-determined condition. When the city energy corresponds to the first pre-determined condition, the city energy is transformed to generate a main power to the load. When the city energy does not correspond to the first pre-determined condition, a fuel cell unit is activated to provide a backup power to the load.