Trains in Switzerland Are Now Running Over Solar Panels in a First-of-Its-Kind Test

The pilot turns unused railway space into a small but closely watched solar test.

A train line in western Switzerland now carries two kinds of traffic: passengers above, and sunlight below.

On a 100-meter stretch of active railway near the village of Buttes, 48 solar panels sit between the rails, low enough for trains to pass over them and removable enough for crews to take them away when the track needs work. The installation, developed by the Swiss startup Sun-Ways, is small. Its 18 kilowatts of capacity could generate about 16,000 kilowatt-hours of electricity a year, roughly the annual use of a few European households.

But this is just a pilot program. If the system works safely on a busy rail line, it could point to a new way of expanding solar power without covering farmland, forests or mountain slopes with panels. That’s perhaps important in Switzerland, more so than in other places, where renewable energy is urgently needed, but new solar projects can face resistance when they move into cherished landscapes. NIMBY is sadly a global phenomenon.

The Buttes project, which became operational on April 24, 2025, is being watched well beyond Switzerland. Sun-Ways has signed a collaboration agreement with SNCF, the French rail operator, giving it access to production data, technical results and operational feedback from the pilot. If all goes well, France may soon follow suit.

A Solar Farm Hidden in Plain Sight

Railways contain an obvious but difficult-to-use resource: long, exposed corridors of open space.

The idea behind Sun-Ways is simple. Instead of building solar farms on new land, place photovoltaic panels in the unused strip between the rails. The company says its panels can be installed by a special railway machine developed with the Swiss track maintenance company Scheuchzer. The machine lays the one-meter-wide panels “like carpet,” using a piston system to unfurl preassembled modules along the track.

Scheuchzer says the system could eventually install up to 1,000 square meters of panels per day, according to reporting cited in the sources.

The key feature is removability. Railways are not exactly empty real estate. They are critical infrastructure that must be inspected, repaired and cleared quickly. A permanent installation between the tracks would likely be a nonstarter. Sun-Ways designed the panels so crews can detach them for maintenance, then reinstall them afterward.

×

Get smarter every day...

Stay ahead with ZME Science and subscribe.

Daily Newsletter
The science you need to know, every weekday.

Weekly Newsletter
A week in science, all in one place. Sends every Sunday.
No spam, ever. Unsubscribe anytime. Review our Privacy Policy.

Thank you! One more thing...

Please check your inbox and confirm your subscription.

“This will be the first time that solar panels will be installed on a railway track with trains that pass over them,” Sun-Ways CEO Joseph Scuderi said.

The Buttes pilot sits on Line 221, operated by regional rail company TransN in the canton of Neuchâtel. During the three-year test, scheduled to run through April 2028, Sun-Ways will study installation and removal, glare, track inspections, compatibility with railway equipment, maintenance impacts, dirt accumulation and energy performance.

SNCF’s innovation department and SNCF Réseau, France’s railway infrastructure manager, are monitoring how the panels affect maintenance and infrastructure availability.

Why This is Harder Than It Looks

Solar panels between rails sound almost obvious. In practice, the railway environment is harsh.

Panels may face vibration, dust, metal particles, snow, ballast movement and repeated pressure waves from passing trains. The panels must not distract drivers. They must not interfere with signaling systems, inspection equipment or emergency work. They also must keep working when laid flat, a less efficient angle than many rooftop arrays.

Regulators noticed those risks and initially said “nope.” Switzerland’s Federal Office of Transport first rejected the project in 2023 as a precautionary measure, citing concerns about railway safety and maintenance. Sun-Ways then spent months building and testing prototypes. The company also brought in scientists for an independent study and Geste Engineering for a safety analysis.

The International Union of Railways has also raised concerns that panels could suffer micro-cracks, increase fire risk or create distracting reflections for drivers.

Sun-Ways says it has addressed those problems with tougher panels, anti-glare coatings and built-in sensors. The company has also proposed cleaning brushes attached to trains to remove dust and debris from the panels as trains pass over them.

The tests now underway are meant to determine whether those answers hold up outside a prototype setting.

Where the Electricity Goes

For now, the electricity from the pilot is expected to feed into the local power grid.

But Sun-Ways has broader ambitions. The company says the power produced between the rails could eventually serve several uses.

“There are three ways to use the photovoltaic current produced: it can be reinjected into the railway company’s LV (low voltage) network to power the railway infrastructure (switches, signals, stations), it is also possible to reinject the current into the electricity network of the nearest local GRD (Distribution Network Operator) or by reinjecting the current into the traction energy network that powers the locomotives,” the company explained.

Scuderi has framed that last option as the ultimate goal.

“In the long term, our ambition is to produce energy between the rails and re-inject it into the traction current of the trains so that it is practically 100% self-propelled,” Scuderi said.

However, that remains a distant target. Trains use large amounts of power, and the Buttes pilot is tiny. But rail networks are vast. That is what makes the idea appealing.

The Land Problem in Solar Power

Solar energy has become one of the cheapest and fastest-growing sources of electricity in the world. But as countries build more of it, the question of where to put panels has become more contentious.

Rooftops are useful, but not every roof is suitable. Large solar farms can be built quickly, but they can compete with agriculture, wildlife or scenic landscapes. In Switzerland, that tension has become especially visible in debates over solar installations in the Alps. In 2023, voters rejected a proposal to place solar panels on mountainsides.

Railway solar fits into a broader trend meant to bypass these issues by putting panels on already-built or already-disturbed spaces. Developers have experimented with solar along highways, over canals, on reservoirs, above parking lots and on farms. These approaches will not replace conventional solar farms, but they can reduce pressure on undeveloped land.

“As controversies grow around the installation of solar power plants in the Alps, Sunways technology could provide a relevant response and the necessary increase in solar-powered electricity production,” Sun-Ways said. “Indeed, it exploits an unused space without disrupting train traffic or maintenance and inspection work on the tracks.”

Sun-Ways has estimated that panels across Switzerland’s roughly 5,000 kilometers of railway could produce about one terawatt-hour of electricity per year, or roughly 2 percent of the country’s electricity consumption. The company says the covered area would be about the size of 760 football fields.

RelatedPosts

New solar power material converts 90 percent of captured light into heat
Solar cells woven into fabric could turn any tent, curtain or clothes into a solar panel
World’s Largest Solar Thermal Energy Plant Opens in California
Blend solar panels with agriculture, new study recommends

The startup has an even larger vision. “There are over a million kilometres of railway lines in the world,” Sun-Ways co-founder Baptiste Danichert said last year, according to Sustainability Magazine. “We believe that 50 per cent of the world’s railways could be equipped with our system.”

That estimate should be treated as an ambition, not a forecast. Many tracks run through tunnels, shaded corridors, snow-heavy regions, complex junctions or areas where maintenance demands would make solar installation impractical. But even a fraction of global rail mileage would represent a large surface for clean power.

Answering a Key Question

Lubomila Jordanova, CEO and founder of Plan A and co-founder of Greentech Alliance, argued that the approach has one major advantage over many new energy projects: it uses land society has already built on.

“This system uses the vast network of underutilised railway tracks for solar energy generation, creating a highly scalable, efficient, and environmentally friendly way to produce clean power,” Jordanova wrote on LinkedIn, according to Sustainability Magazine.

“A key advantage of this innovation is that it capitalises on existing infrastructure, eliminating the need for acquiring additional land for solar farms,” she added.

For now, the Swiss pilot will answer a more practical question: not whether the world has enough railway space for solar panels, but whether solar panels can survive the railway.

If they can, one of the next clean-energy frontiers may not be a desert or a mountaintop. It may be the narrow strip of gravel and steel already running through towns, farms and forests.