A novel technique for efficiently extracting the maximum output power from a solar panel under varying meteorological conditions is presented. The methodology is based on connecting a pulsewidth-modulated (PWM) DC/DC SEPIC or Cuk converter between a solar panel and a load or battery bus. The converter operates in discontinuous capacitor voltage mode whilst its input current is continuous. By modulating a small-signal sinusoidal perturbation into the duty cycle of the main switch and comparing the maximum variation in the input voltage and the voltage stress of the main switch, the maximum power point of the panel can be located. This approach ensures maximum power transfer under all conditions without using microprocessors for calculation. The tracking capability of the proposed technique has been verified experimentally with a 10 W solar panel at different insolation levels and under simulated large-signal insolation level changes.
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