Tough Solar: Casio’s proprietary solar charging system. Casio’s Tough Solar converts not only sunlight, but even light from weaker light sources, such as lamps, into power for the watch.
How it works:
A solar panel within the watch face combined with a large-capacity rechargeable battery produces enough power to drive multiple power-hungry functions effectively and reliably.
The area on the watch for the LCD, dial printing, and other elements is calculated precisely to permit installation of a highly resilient, film-like solar panel on the dial. Six solar cells are connected in a series to receive the same amount of light to power the watch and its functions efficiently.