Solar chargers have come a long way thanks to new high-efficiency panels and rugged designs. We favor units with an onboard battery, which let us bank energy to use in driving rain, at night, and in emergencies; the ones we used for this test all charged their own lightweight lithium-ion in four to six hours of direct sunlight. These devices should always have a mini-USB connection to keep your phone, camera, or e-book topped off.
When shopping for a solar changer, keep in mind the two basic kinds of panels: rigid monocrystalline and the flexible thin-film. Your decision should be based on which kind will work best given the weather conditions in the areas where you like to explore. Rigid panels generate more electricity in bright sunlight, but most don’t generate much energy at all under clouds. Flexible thin-film panels are less efficient, but make more juice on cloudy days. They also roll up into a small package, which is great when you're traveling with a full pack.
Keep your eyes out for new developments. The field is evolving fast, and the prices and efficiency of thin-film roll-up panels are getting better all the time. After the jump, we run down the best new portable chargers available now and the most promising ones coming up.