the invention is directed to a method , system and device for converting direct current electrical voltage from a fuel cell to an alternating current voltage . the inventive method regulates power drawn from the fuel cell and from a battery to maintain a substantially constant dc voltage across a dc bus , and inverts the dc voltage from the dc bus to the ac voltage . the method may further electrically isolate the fuel cell from the load . also , the inventive method may prevent current from flowing to the fuel cell . the inventive method may also provide a charging current to the battery .