Simple(?) Timer Circuit

Hoping for some direction (or full-blown assistance)...

I wish to rotate a compost barrel.  (Apparently it dramatically speeds up the composting process.)

Obviously just connecting the panel directly to the motor wouldn't work.  There wouldn't be enough current to turn it.  Obviously the more times the barrel rotates, the better.  But I'll take whatever I can get.  If it's only 20 times in a day then so be it.

I'd like a simple circuit with as few components as possible.  And would prefer not to use a battery.  That way I don't need to monitor battery charge/condition, etc.

My first thoughts were, to bolt a bicycle cog onto one end of the barrel, and drive it via a chain, using a DC motor.  The motor would perhaps be something like a car windshield wiper motor.  A very small solar panel charges a largish capacitor over several minutes.  When there's enough charge in the capacitor, the circuit triggers and turns the motor and barrel a little.

I think making the circuit sense when the capacitor is fully charged and triggering, would make the circuit more complex - thus requiring more components.  So maybe it's easier to charge 'blind' for 5-10 minutes - and just dump any excess charge instead - but I'm not sure!?

I'm not finding any circuits like what I'm describing.  Can anyone help?