Patent ID: 8358099

Claim:
An electric power system comprising: a main module; and a sub-module, the main module comprising: a load; a main renewable energy power generating apparatus that generates electric power from renewable energy; a main battery pack connected to the main renewable energy power generating apparatus with a plurality of rechargeable batteries connected in series and/or parallel that are charged by power generated by the main renewable energy power generating apparatus; a switching device connected between the main battery pack and the load to supply power from the main battery pack to the load; a main control circuit that controls load illumination by controlling the switching device ON and OFF; and a main reverse current protection diode connected in series with the switching device at the output-side of the main battery pack to allow main battery pack discharge to the load while preventing current flow from the load-side back to the main battery pack, the sub-module comprising: a sub-battery pack connected in parallel with main battery pack of the main module with a plurality of rechargeable batteries connected in series and/or parallel; a sub-renewable energy power generating apparatus that charges the sub-battery pack; and a sub-reverse current protection diode connected in series with the switching device at the output-side of the sub-battery pack to allow sub-battery pack discharge to the load while preventing current flow from the load-side back to the sub-battery pack, wherein the output-side of the sub-reverse current protection diode is connected to a connection point between the main module main reverse current protection diode and the switching device to allow power to be supplied to the load from the sub-battery pack through the sub-reverse current protection diode and the switching device, and the main module main control circuit controls the switching device ON and OFF to supply power from both the main module main battery pack and the sub-module sub-battery pack.