I helped a group of college students on their solar powered car project.
The body of the car was covered with solar panels. Each had its own MPPT
converter. The MPPT converter was a simple boost converter run by a PIC.
The PIC would dither the PWM based on measured current leaving the
converter and heading towards the battery. If the last duty cycle step
gave us increased current into the battery from this converter, we'd
adjust the duty cycle in that direction again, then measure the current
again. If the measured current was lower than the last one, we'd adjust
the duty cycle the other way. "Every now and then" the PIC would sweep the
entire acceptable duty cycle range to find the maximum. This insured we
did not get stuck on a relative maximum somewhere (though relative maxima
should not exist, just an absolute maximum).

The converter per panel worked out nicely since each panel was illuminated
differently. This project was 5 to 10 years ago.

Harold


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