I've done several solar powered trips and some have worked out better than others. Charging while on the move is a bust unless you're in a treeless area and heading more or less north since as Trailrunner said you block the panel with your head and hat. I did try putting a small panel on my hat but that was just too annoying and it was too small to be much use. A larger panel did work well on trips where I had lots of time in a camp with sun exposure near by. That was using a 5w panel with a bit of electronic circuitry to bring the voltage down and the current up to match the battery. That was fine for a Palm TX, a camera and some AA cells. The weight is too high for short trips but past 4 or 5 days, depending on you power requirements, it starts making sense.