I believe the ccrane.com company sells a solar battery charger. I have a bike light that is solar powered and has internal cells inaddition to the ability to accept cells.
I am guessing since solar needs surface area and direct sunlight it is not worth their weight to carry on a trip.
There's lots of solar chargers available. They do make sense for very long expeditions. For short and medium expeditions, unless there are unusual power requirements, the chargers weigh more than the batteries they replace.
amorphous means it will bend a bit, amorphous cells are less power, and because they are plastic instead of glass, i bet they dont last as many years at all, mabey 5-10