The Eco-Drive for Watches

Eco-Drive is a hidden solar power system for watches, created by Citizen. Watches with the Eco-Drive system look just like regular watches — there is no solar "panel" to be seen. Sunlight is absorbed through the crystal and the dial of the watch. A solar cell below the dial converts the lights into electrical energy. An Eco-Drive "Energy Cell" stores enough energy to power the watch for five years. Citizen doesn't say exactly what the energy cell is made out of, but they do say the cell contains less caustic materials than a regular battery. They also say it will function for the lifetime of the watch, and it doesn't need replacement. Citizen has an FAQ on the technology behind the Eco-Drive here. :: Citizen Watches [by Justin Thomas]