Switzerland just celebrated a full year of running trains directly atop the world’s first solar power plant integrated into an active railway line, and the results are promising enough that Italy could become the next country to try the same idea.
The project, developed by Swiss startup Sun-Ways, involves 48 specially designed solar panels installed between beams spanning a hundred meters of track in the village of Butts, in the canton of Neuchâtel. Trains continued to run over the panels exactly as before, with no interruptions to services or any incidents to distract drivers, although the setup was originally approved as only a three-year trial.
With these early results holding steady, Sun-Ways has now signed a cooperation agreement with an Italian partner that is in contact with the country’s national railway operator, and several other countries are watching closely as well.
How solar panels ended up between railway lines
The idea behind Sun-Ways is fairly simple, as railway corridors represent a large area of sun-exposed open land that already exists and is rarely used for anything outside of the tracks themselves, making them an obvious candidate for solar energy without the need to purchase or clear any new land.
The panels are placed directly on the beams between the rails, and are designed to be removable, since maintenance crews regularly need to access the tracks underneath to perform repairs, milling and general maintenance.
A specially designed machine developed by Swiss maintenance company Scheuchzer can place or remove nearly a thousand square meters of panels in a single day, addressing one of the biggest practical objections that have previously hampered the use of similar solar energy in railway concepts elsewhere in the world.
Addressing safety concerns by rail regulators
Before the pilot could begin, Sun-Ways had to answer some safety concerns raised by rail regulators and industry bodies. The International Union of Railways has expressed concerns that the panels could develop small cracks under the constant shaking of passing trains, increase the risk of fires, or reflect sunlight in a way that could distract drivers. Sun-Ways responded by building panels that were stiffer than standard rooftop versions and equipping them with an anti-reflection filter, along with built-in sensors to monitor their condition and brushes attached to passing trains that automatically removed dirt from the panel surfaces.
According to an update reported by Swiss public broadcaster SWI swissinfo.ch, Swiss authorities rejected the project once before, in 2023, due to the same maintenance and safety concerns, before eventually agreeing to a three-year pilot once Sun-Ways commissioned an independent engineering study to prove that the panels would not interfere with active rail operations.
Why are the results after one year so encouraging?
A year into what was supposed to be a longer trial, Sun-Ways reported that the installation worked without any issues and required no special maintenance beyond what was originally planned.
Electricity generated by the panels is currently fed directly into the local power grid rather than directly into the railway’s traction system, although the company says it is already working on a version that could eventually power trains directly, moving towards what it describes as an almost self-propelled railway.
If the panels were deployed across Switzerland’s entire roughly 5,300-kilometre railway network, excluding tunnels and poorly lit stretches by sunlight, Sun-Ways estimates the system could generate about a terawatt-hour of electricity per year, enough to power nearly 300,000 households and cover roughly two percent of the country’s total electricity consumption.
The physics behind why tilt angle actually matters
One technical limitation of laying solar panels flat between railway tracks is that they cannot be oriented toward the sun as is typically the case with rooftop panels, which naturally reduces how efficiently they capture sunlight over the course of a year. According to a study published in the journal Sustainable Energy Technologies and Evaluations, researchers who analyzed photovoltaic systems across the Iberian Peninsula found that a constant tilt angle of about 34 degrees kept annual production losses less than one percent compared to a panel with an ideal angle for each specific location throughout the year, because the ideal tilt angle does not vary significantly enough across most of a single region to meaningfully affect overall output.
Sun-Ways has separately estimated that the complete absence of any slope on rail-mounted panels costs about ten percent more potential production than an optimally sloped deck system, a manageable trade-off given the amount of unused space the design opens up in return.
Why are Italy and other countries paying attention?
Following positive results in Switzerland, Sun-Ways has signed a cooperation contract with an Italian business partner already in contact with Rete Ferroviaria Italiana, the company that manages the country’s national railway infrastructure, with plans for an Italian pilot project expected to be announced in the coming months.
Italy is not alone in expressing interest, Sun-Ways has also received government approval to set up a similar facility in South Korea, while discussions are reportedly underway with companies and rail authorities in France, the Netherlands, China, India and Singapore.
French national railway company SNCF, which describes itself as the country’s largest electricity consumer and second-largest landowner, has already signed its own cooperation agreement with the Swiss company as it works towards the goal of meeting a fifth of its energy consumption through solar energy by 2030.
What still needs to be proven before it can be rolled out more widely?
Despite the encouraging early data, Sunwise and outside observers agree that there is still a lot of testing before solar railways can be considered a proven, scalable technology, rather than a promising experiment. Regulatory approval itself has proven slow, with Sunwise founder Joseph Scuderi noting that it took nearly three years to obtain authorization in Switzerland alone, and calling on regulators to create a dedicated sandbox that would allow similar innovative infrastructure projects to be tested more quickly while official rules catch up.
Countries such as Japan and Indonesia have said they are closely monitoring the Swiss trial but want more long-term data on maintenance and safety costs before committing to projects of their own, a cautious approach that suggests the real test for solar railways will be less about whether the technology works, and more about whether it can be scaled up affordably across larger, more widely used railway networks that exist elsewhere in the world.