This solar panel is designed to charge 2 or 4 AA batteries, which is what most headtorches and GPS receivers use. The weatherproof casing can be attached to the lid of your rucksack so you can charge batteries during the day while on the move. It comes with a battery holder and a set of straps so that it can be stuck to the inside of a window. It has a lower power output and is relatively large. Also there is no protective casing, so you might need to protect it when it’s in your rucksack. It comes supplied with a housing to store your batteries while they charge. The ability to strap this to your rucksack is a real bonus though, and it’s probably the main reason for choosing it.
Power output: 1.2W
Charging time: 5 hours to charge 2xAA batteries