Patent ID: 8180499

Claim:
A power supply system, comprising: a cogeneration unit equipped with; an internal combustion engine, a generator driven by the engine to generate power to be supplied to a power destination, a hot water tank for supplying hot water to a hot water destination by selectively using heat exhausted from the engine and an electric heater to heat the hot water, and a cogeneration unit (CU) controller for controlling the operation of the cogeneration unit; a natural energy generation unit that generates power with natural energy; a power supply unit, including a power supply unit (PSU) controller, that receives the power generated by the generator and the natural energy generation unit to supply the received power to the power destination; a connecting bus that electrically connects the cogeneration unit, the natural energy generation unit and the power supply unit; a voltage detector that detects voltage of the power flowing through the connecting bus; wherein the power supply unit controller controls operation of the electric heater based on the detected connecting bus power voltage.