The Dark Energy Spectre 18W Folding Solar Panel is built for the kind of trip where the power source needs to survive the same conditions as the rest of the kit. Photo-Skyn flexible cells keep current flowing in overcast light, and the Armor-Flex shell is tough enough to ride at the bottom of a loaded pack all day so it's ready to deploy at camp without inspection. What Our Gearhead(R) Experts Are Saying:"The built-in sun meter takes the guesswork out of placement. Four LEDs tell me exactly when I've found the angle that's actually charging versus just sitting in partial shade."