Electric power supply system

An electronic power supply system, comprising:

• an inverter coupled to and supplying power to a load;
• a first power source portion supplying power to said inverter;
• a second power source portion used in combination with said first power source portion for supplying the inverter with any deficiency of power supplied to the inverter from said first power source portion,
• said second power source portion including an alternating current power source and a voltage multiplying rectifier circuit, and
• wherein said first power source portion includes a solar power source, a system power control circuit connected to said solar power source, a voltage detector for detecting and generating a first signal VLD corresponding to the value of an input voltage to said inverter and an insolation sensor for detecting and generating a second signal Ee corresponding to the value of the output voltage of the solar power source,
• said system power control circuit further comprising, a switching element and controller circuit means including a signal processor responsive to said first and second signals for controlling the on/off duty cycle ratio D of said switching element, said switching element controlling the voltage amplitude of said first signal so as to set a predetermined maximum value Vset thereof, and wherein an initial value of said duty cycle ratio D is stored in a memory of said signal processor and is variable in increments of .DELTA.D, said increments further being initially set and stored in said memory, said signal processor duty cycle ratio D controlling the voltage amplitude of said first signal VLD such that VLD is decreased by said increments of .DELTA.D when Vset>VLD and increased when Vset<VLD, whereby the solar source operates at a maximum power point.