The Poweradd Apollo 2 was the most pleasant surprise in our review. It is the size of a smartphone, and it will recharge your smartphone three to four times before needing to be recharged in the sun. Its solar panel is small but high quality--however, it still takes about 50 hours to recharge in sunlight. While this sounds like a long time, we found it to be attainable, given that you have a large reserve of three to four smartphone charges and up to two tablet charges before draining the battery. As such, it gets our Top Pick award for a small, battery-included solar panel.
The best strategy with this charger, we found, was to charge our devices with it at night, and set it out all day in the sun, when possible. In this way, for a camp of about two people, we found we could get a week or more of charges for our smartphones and tablets--the battery would hold enough reserve charges that it replenished plenty fast, and we never ran out.
An even bigger surprise was watching how quickly the Apollo 2 charged our smartphones, only to be more stunned by the speed at which it charged our iPads. With two USB ports, one at 2.1 and the other 1.7 amps, this solar charger is fast, powerful, and efficient--and it all fits easily in your pocket.