jremington:
Batteries are all roughly the same as far as their efficiency is concerned. They differ in their chemistry and capacity in Ampere hours (Ah) or milliampere hours (mAh).First you have to decide what your use will be: what voltage and what current will your application circuitry require, and for how long should it run on the battery alone?
Then choose the battery, to provide the required voltage and current, for the desired hours. Then choose the charger/solar cell options.
Ok, for now I just want to recharge a standard LiPo power bank as efficiently as possible using the above-described solar panel. Say, a 5600mAH or 11200mAH one. That IS the application.
So, with the panel in a fixed location and angle and given its specs as described above, what kinds of charge controller boards are recommended? Surely there are certain ones that the community tends to prefer, for relatively low-power applications like this, especially less expensive ($5-$10) ones.
And if a charge controller is overkill, then what kind of DC-DC voltage converter board do you recommend?
I'm not looking for an optimal solution at this point that requires the engineering approach you're all recommending here. I'm looking for a general-purpose solution that would work for this app. I went to engineering school and know how to do things "right". But I'm taking a tinkerer/hobbyist approach here.
I.e. the "fun" approach someone has in their sig line.