I have a 20W 5V solar panel (real output more like 10W in bright sun). Would like to harvest as much solar power as possible to a power bank to power a bluetooth speaker (< 5W consumption). Bright clear skies are a luxury where I am. The panel voltage fluctuates depending on the clouds etc, - damaged the circuit of a powerbank. Need something to act as a buffer.
I am considering a circuit using super capacitors (2 in series 2.7V 500F) as energy collectors / buffer -- let the voltage build up to ~ 4.5V. Switch on the circuit at 4.5V and a boost/buck circuit mops up the power to charge a power bank. The switch is on till the voltage drops to ~2V. When the voltage drops to ~2V the switch turns off and stays off till the voltage rises up to ~4.5V again.
Are such configurable switching circuits available where one can set the upper and lower voltages? Or Is it easy to make one?
Or should I try a different approach altogether?
Looking forward to your suggestions.
simulate this circuit – Schematic created using CircuitLab
PS - Apologies, I am a newbie in the world of circuits.