There is always a huge debate about solar chargers among photographers who operate in the field. In particular, on expeditions to areas which are almost always heavily forested, like the Amazon. Photo.net probably has hundreds of threads now about such products.
I am very hesitant to suggest them, because batteries are so much cheaper, and because while heavy, they actually work in the dark.
Unless you have VERY esoteric needs, a device that cannot otherwise be charged (and extra batteries are impractical), or will be out for more than two weeks, I doubt it is worth the money over batteries.
