Evolution of the Sundial
1. Synchronar - Conceived in the early sixties and first produced in 1968, the first Solar watch ever was invented by the reclusive inventor Roger Riehl. Solar panels on the top with a sideview LED display. Heavily debated within a microcosm of vintage watch collectors as the first digital watch ever. That distinction is commonly given to the 1970's Pulsar LED. 
2. Nepro - 1975 LED with raised display and backside solar panels. 
3. Uranus - "This is one of the earliest LED watches in existence. It is one of the very earliest "wearable" wristwatches made by Uranus (approx. 1971) and one of only a few made (hugely expensive to build). It actually predates the Pulsar and launched Uranus into a patent fight with Hamilton (Uranus lost). The thing that makes this watch unique is that it does not use an LSI (large scale integrated chip) but instead is made up of discrete logic and driver chips using hundreds of wire bonds to connect them up. It is truly a packaging marvel. The display is only hours and minutes. The face is divided in half horizontally with the LED in the upper half, the lower half being composed of solar cells in a fan pattern to supplement the battery, all in a gold filled case." by Guy Ball
4. Sicura LCD - 1976 LCD with innovative solution of putting solar panels on the side of the watch.
Sicura Ad
5. Sicura Analog - 1978 Analog version of the same watch.
6. Junghans 'Mega Solar' - 1990's radio-controlled, PVD-coated wristwatch with solar cell, date and integrated radio receiver from one of the most accurate clocks in the world - the Caesium Time Base at Germany’s National Institute of Natural Engineering and Sciences.
7. Citizen Crystron - 1976 "This was the first solar-powered analog wristwatch. It conformed to the conventional design of most analog watches except for the four square gray panels that take up most of the face. This watch began Citizen’s long-term commitment to solar powered watches, which has culminated in the very successful Eco-Drive line of watches." by Soluhr
8. Calcron & Louis Erard Calculator Watches - Mid to late seventies solar calculator watches with side panels. The non-solar Calcron is believed to be the first ever wrist-calculator watch made as originally featured here-->Link
9. Cristalonic 'Solar Quartz' by GmbH - 1980's LCD with an asymmetric black plastic case.
Cristalonic Advertisements
10. Lorus - 1980's solar LCD. A division of Seiko.
Sadly, development of the modern light-powered watch, like the Citizen Eco-Drive, eliminated the need for innovative visual configurations as solar panels now absorb light through traditional watch dials. It was fun while it lasted...
