I wouldnt just wander out and let it play for hours to test the theory of how long it lasts. I havent personally used a solar charger, but i dont think it would totally keep it charged, but it wont hurt it either. Like i said, get a battery pack and go enjoy your tunes. Try an hour or 2 then maybe do it a bit longer next time. With just 2 speakers though, you should be fine a while.