Ok, so I've been having much success with the joule thief circuit and a LED, but i tried hooking it up to a small solar panel that can put out 2.5v on it's own, and can light up a white LED dimly by it self to the joule thief and it will not work ....my question is why? I already trouble shooted it, the circuit is not the problem, is it the amount of amps the small solar panel is capable of? not enough?
Solar panels convert light energy to electrical energy with an efficiency of around 5%. A SMALL solar panel will only produce a small amount of power (watts) your joule thief circuit wont help because as you draw more current from the solar panel the voltage will drop; and your joule thief circuit just reduces the efficiency of the whole system Try adding another solar cell in series to get more voltage and more power.