Well, I can’t help you with this specific question…
But…
It brings up an interesting point. Powering portable audio devices entirely by solar power is possible, and a fun $30 - $50 DIY project for those who feel up to it.
Basically, for two AA or AAA devices you’ve got to get 6 individual 0.45volt semi crystalline or crystalline solar cells, each with at least 500ma current producing ability. Solder them in series to get the voltage up to 2.7. Encapsulate them by embedding them in some epoxy set upon scraps of clear polycarbonate “lexan” which can then be made into a sealed housing.
I made a few of these things once, but I made the mistake of not embedding the brittle cells in anything. One drop and they shattered. I used cheap acrylic plastic as the housing too, which was frail and prone to heavy scratching. Hmm… I might have to make a new super solar cell soon –“done right” this time!
By the way, the reason it’s best as a DIY is that the commercially available mini solar panels for charging cell phone batteries etc., have the wrong voltage current ratings to power any realistic device. You want 3 or 6 volts more likely, at 500ma to 1 amp. Not high voltages at low currents, like the typical 12 volts at 100ma that these things usually come in. bah. Plus, you can build your own better super strong housings from scraps…
