Synchronar 2100 Solar powered wristwatch, c. 1980
Ragen Semiconductors, Inc, Whippany, New Jersey
This watch gets its power from a never-ending source: the sun. The large panels, located where the time display would normally be, are solar cells. They absorb energy from the sun and convert it to electricity, which is what makes the watch run. Fourteen hours of exposure to sunlight charges the watch completely. Once fully charged, the watch can supposedly run uninterrupted for six months, if given fifteen additional minutes of sunlight daily. The "2100" in its name comes from the manufacturing company's guarantee that the watch is accurate until the year 2100.
With the solar cells on the face of the watch, the time display moves to the edge of the case, near the watchband. According to the manufacturing company, this allows for a more natural viewing position. The time and date can be set using the magnetic switches on either side of the solar cells. The watch conserves energy by shutting off the display after a prolonged period of darkness. Despite its energy-saving potential, solar power has not yet become the dominant energy source for watches.