I’ve used lots of solar chargers and none has proved as reliable as the Monkey, which was my constant companion during a summer’s worth of weeklong outings in the Sierra. It solves the three main problems that plague its competitors.
First, it charges quickly (one day of full sun nets one day of use with my GPS, and in overcast conditions it takes about two and a half times longer, which is still better than most) and the LED display tells me exactly how much juice I have left.
Second, the bullet-shaped battery (it attaches to the flip-out solar panel) holds a lot of power—enough to run the SanDisk (below) for 35 hours. And third, the Monkey comes with 11 adapter tips that let me charge every device I pack (and all reviewed here). $120; 3 oz.; powertravellerusa.com.