Tour de Sol
The Tour de Sol was Switzerland’s first rally for solar-powered vehicles, held every year from 1985 to 1993. The opening race ran June 25–30 from Romanshorn on Lake Constance to Geneva. Seventy-two vehicles started in two classes and more than half finished. The vehicles ran on power from onboard solar cells plus an initial battery charge; a second class allowed pedaling as well.
It was run like a race, with the fastest to complete each day’s course winning. The routes used public roads and drivers had to follow traffic rules. In the early years the rallies drew large crowds, and later some stages used fast, closed circuits at the stops. In 1990 the organizers added Tour de Sol Alpine, with events on frozen lakes, snowy roads, and mountain passes. A solar-powered boat race began in 1988.
Rules evolved over time. At first only direct solar power from onboard cells was allowed. Later a class allowed charging from stationary solar panels and swapping batteries, and another allowed charging from the mains (230 V) only if the electricity came from solar power elsewhere and was fed into the grid. This helped spur early grid-feed systems.
The Tour de Sol was organized as a foundation and ended in 2002. Inventor Josef Jenni is credited with creating the event, and Urs Muntwyler led it for most years. The courses started flat but later included more winding routes with mountain passes. A 24-page handbook described vehicle rules, including solar panel size and battery capacity. Racing cars could have up to 6 m2 of solar panels (480 W peak) and up to 4.8 kWh of batteries. Vehicles were police-checked and given temporary licenses for the rally. Most vehicles had three or four wheels, but a few solar-powered bicycles with trailers took part, helping spur Swiss electric bikes and motorcycles.
This page was last edited on 2 February 2026, at 05:23 (CET).