Solar Paper works in essentially the same way as any other portable USB charger. When you need to juice up your phone just plug it into the device and it’ll charge it up for you. Unlike those other devices, Solar Paper is fueled by an unlimited and eco-friendly power source—the sun.
The ultra-thin Solar Paper is, according to creator Yolk, the most efficient solar panel on the consumer market. It apparently can fully charge an iPhone in two hours (about the same as a wall charger.) If you move into shadow, it’ll stop charging, but the auto-reset feature means that it’ll switch back on when back in the light.
Each panel generates 2.5 watts of power, so for an iPhone that takes a 5-watt charge, you need two panels. The additional panels connect magnetically so more panels mean more power. For example, most tablets need 10 watts, so to charge an iPad you’d need four panels.
You don’t need to be outside to use Solar Paper—Yolk has a video showing someone using it in an airplane window—but you do need bright sunlight. It’s definitely most useful for hikers, campers, and other outdoor adventurers. Between taking pictures and using GPS, your phone can drain pretty quickly and you don’t want to be caught with a dead battery if you get lost or need to call for help.
Each Solar Paper panel comes with holes punched in the corners so you can hang your solar charger on your backpack to keep charging on the go.