Using modern technology it is a possibility. Remember one doesn't need direct sunlight, increasingly daylight is sufficient to create a charge and this should improve in the future. Obviously there is the issue of the battery losing it's memory when on a constant trickle charge though I believe this issue is also being improved.
I would say this is not a totally daft idea as at first seems the case but....time will tell as with all technological advances, I remember when Startrek communicators were just so much idiocy...