The present invention relates to a domestic combined heat and power system, and the domestic combined heat and power system includes a power unit, a heat-storage tank which receives waste heat of the power unit and stores heat in direct water, and a main heat exchanger which is connected to the heat-storage tank and is heated by a burner so as to use the water as hot water or heating water, in which a waste-heat heat exchanger filled with a heat-transfer medium is installed between the power unit and the heat-storage tank such that a waste-heat pipe of the power unit is arranged in the form of a coil at one side inside the waste-heat heat exchanger, and a heat-storage pipe of the heat-storage tank is arranged in the form of a coil at the other side, so that waste heat of the power unit is indirectly heat exchanged to the heat-storage tank through the heat-transfer medium; in which hot-water piping coming out from the heat-storage tank is arranged so as to be indirectly heat exchanged via a hot-water heat exchanger, and heating piping coming out from the heat-storage tank is connected to the heating water-heat exchanger, and a part of the heating piping again comes out and is arranged so as to be indirectly heat exchanged via the hot-water heat exchanger. According to the present invention, since a heat-exchange method for the power unit and the heat-storage tank is changed into an indirect heat-exchange method, costs and waste of energy consumption are reduced, and there is sharing of functions that are duplicated across the heat-storage tank and a boiler such that efficient system design is possible, variability and compatibility are enhanced, and the system volume is reduced such that installation space may be more effectively used.