It’s a portable socket that gets its power from the sun rather than the grid. You plug into a window instead of into the wall. It’s easy.

That was the whole point, according to the designers, Kyohu Song and Boa Oh: “We tried to design a portable socket, so that users can use it intuitively without special training,” they write.

It is really simple. The portable socket attaches to a window like a leech to human skin. On its underside, it has solar panels:

The solar panels suck energy from the sun. The charger converts that energy into electricity. You plug in to the charger.

Even better, the charger stores that energy. After five to eight hours of charging, the socket provides 10 hours of use. You can pop it off the window, stick it in your bag, and use it to charge up your phone with solar energy, even if you’re sitting in a dark room.