DC POWER SUPPLY SYSTEM AND LIGHTING APPARATUS

PROBLEM TO BE SOLVED: To provide a low-cost DC power supply system, which supplies DC power using a commercial AC power source and natural energy, capable of efficiently utilizing natural energy even when the power generated thereby is small.SOLUTION: An DC power supply system 10 of the embodiment includes; a full wave rectifier circuit 40 for outputting a predetermined voltage using a commercial ac power source; solar cells 3 for generating power using solar energy; a voltage booster circuit 39 for boosting the output voltage of the solar cells 3; a solar cell power supply circuit 33 having control means 47 for controlling switching of the voltage booster circuit 39; backflow prevention components, which supplies power to a load, including a first diode 34 having the anode thereof connected to the full wave rectifier circuit 40 and a second diode 35 having the anode thereof connected to the solar cell power supply circuit 33 and the cathode thereof connected to an output terminal together with the cathode of the first diode 34. The control means 47 changes the duty ratio of a switching control signal to the voltage booster circuit 39 such that the output voltage of the solar cells 3 is maintained at a predetermined voltage.