A system, method and device for power switching and power control, particularly for switching the source of power between two or more power sources are provided. Power control elements testing the availability and stability of alternate power sources and switch loads between these power sources in short periods of time and with advantageous switching characteristics. In a fuel-cell system, the embodiments of the invention may be advantageously deployed to power up balance of plant loads using opto-electronic couplers and electronic relays.