Solar E-Bike Carries Its Builder Over the Alps, Despite Heat and Hills

Shawn Ryan entered the 2026 Sun Trip Alps with an unusual goal: to find out how far a heavily loaded electric bicycle could travel using sunlight as its only intended fuel source. The answer was more than 1,000 kilometers across France, including climbs over the Col du Galibier and the Col de l’Iseran. Ryan’s machine was built around an Omnium cargo bike fitted with two solar panels, a 250-watt Tongsheng mid-drive motor, two 36-volt batteries and a charge controller he connected to the solar system. Ryan originally planned to use three 100-watt panels. Testing in Nottingham, UK, showed that the wider setup made the bike awkward in traffic and confined spaces, so he reduced the array to 200 watts. With camping and camera equipment aboard, the finished bike weighed about 61 kilograms. The smaller array left little room for error. Although the panels were rated at 200 watts, their actual output varied between 70 and 100 watts depending on sunlight and panel angle. On Ryan’s most demanding day, he covered 130 kilometers through mountainous terrain while the system recorded 985 watt-hours of usable solar energy. The biggest problem came during a French heatwave, when temperatures reached 41 degrees Celsius. One battery’s management system overheated and stopped accepting solar charge for periods of the day. Ryan said the system was protecting the battery, but the interruption meant some available solar energy could not be stored. He believes mounting the battery in a shaded location might have helped, while also noting that the battery’s construction may have contributed to heat from electrical resistance. He said he could not identify the cause definitively. The motor also overheated on some long climbs. Ryan dealt with that by stopping to let it cool, occasionally pouring water over its casing, and using low gears to keep the motor spinning at higher speed. He ultimately used mains electricity twice, totaling about 1 kilowatt-hour. That allowed him to continue the rally but removed him from the solar-only points competition. Ryan said the 200-watt system came close to meeting the bike’s needs on favorable days, but provided little reserve in changing weather and steep terrain. The Alpine bicycle was a prototype for a larger project. Ryan is considering a semi-recumbent, long-wheelbase design with a broader solar canopy for the proposed 2028 Sun Trip from France to China, a provisional route of roughly 15,000 kilometers. The route and rules have not yet been finalized.