A resistor in series is the simplest way.

You can slow charge while powering a light load, then short the resistor
into the load for a burst of current for a high load, but if that's not
enough, will you still have enough to charge the capacitor AND power a
medium load.

It won't get you up a hill, but it might be enough to get you rolling.
Gearing change might be more versatile for the same weight


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here's nikesh jain from india want to know best mechanism for making
an solarroller which takes less time to cross the 1mts arena in
smallest possible time