A power supply system includes an energy generator and an energy storage system, each electrically connected to a power bus. The power bus provides electrical power to a load. The energy generator includes a wind turbine and a solar panel. The energy storage system includes a storage device and a regulator. The regulator is configured to transfer energy from the power bus to the storage device when the power bus exceeds a maximum voltage and to transfer energy from the storage device to the power bus when the power bus drops below a minimum voltage.