Invisible Solar Panels Hide In Plain Sight, In Railroad Tracks

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Local opposition to new solar projects has been giving headaches to solar developers. However, human nature being what it is, solar innovators are determined to give critics the slip. The latest demonstration of photovoltaic ingenuity comes from the Swiss firm Sun-Ways, which is piloting a system to hide solar panels in plain sight, in between railway tracks.

Solar Panels In Railway Tracks: A Sensible Solution

Laying solar panels in between railroad tracks makes pretty good sense. The main criticisms of rural solar development involve appropriate land use and aesthetic issues, but those matters have long been settled for the many railroad rights-of-way criss-crossing the globe. Railroads are established, permitted, and permanent elements of modern infrastructure. Aside from freight yards and other busy parts of a rail system, railroads are also empty of traffic for long periods of time, allowing for ample sun exposure.

In addition, railroads can offer the solar industry the important element of flat and relatively level sites for development, without having to construct new access roads and other infrastructure. Although the flat configuration and the absence of tracking is not optimal for solar energy harvesting, that can be offset by the savings of reducing racking systems to the bare minimum. The railroad solution also enables developers to avoid disrupting natural habitats or taking space away from other potential land uses.

A parallel strategy of deploying existing infrastructure for solar development is already under exploration for highways. One option consists of raising solar canopies over the sections of roadway, similar to the solar canopies already in use over parking lots and canals. However, that approach could run into objections on aesthetic grounds.

Embedding solar material into the roadway would be a more aesthetic solution. However, the durable, cost-efficient technology to make it happen has yet to emerge. The closest thing to a road-embedded solar energy harvesting system to cross the CleanTechnica radar is a solar panel designed for installation on footpaths.

Solar Panels & The Electric Train Connection

Overcoming aesthetic, environmental, and land use objections is one set of pluses on the side of railroad-embedded solar panels. Another benefit is to support the decarbonization of railway systems. However, Sun-Ways cautions that directly powering switches, signals and other equipment would involve the additional expense and complication of installing inverters.

Instead, Sun-Ways advises that the most cost-effective way to deploy electricity from the panels is to shunt it to a grid. Railways could retrieve the equivalent kilowatts via local substations. Reserving local grids for the solar panels is another option, available in Switzerland through the GRD system.

Another thing to think about is the potential for integrating emerging technologies. I’m thinking of wireless charging which would enable battery-powered trains to recharge along their route. One potential early adopter is the mining industry, where some stakeholders are already electrifying their transportation systems. Last year the Pennsylvania-based locomotive firm Wabtec, for example, fielded an order of three electric locomotives for a iron mine in Brazil (see more electric train news here).

Sun-Ways also seems to have its eye on the future. The translated version of the company website refers to the potential for taking advantage of “the current development of power electronics in the field of linear photovoltaics,” with the aim of shunting electricity directly into the “train traction network” to create “Smart Hubs.” If you know French and can clarify that for our readers, drop a note in the comment thread (here’s the Sun-Ways link in original language).

Solving The Maintenance Problem

Harvesting clean kilowatts without disturbing the aesthetic peace of the countryside is an alluring goal, but the devil is in the details. One of those details is the need for railway maintenance and repair. Aside from replacing railroad ties or whole sections of railroad, Sun-Ways also notes that the ballast (crushed rock) also needs periodic attention. The solution is a removable system that can be taken up as easily as it is put down.

“Usually, the term removable does not apply to solar panels, readily which are imagined fixed definitively. But in the case of Sun-Ways, removable becomes an essential feature,” Sun-Ways explains on its website.

For installation, Sun-Ways loads the solar panels onto a work train in a continuous roll, which is unrolled like a carpet as the train moves down the tracks. Removal is a matter of sending a work train back along the tracks to roll up the panels.

Another challenge is keeping the solar panels clean enough to operate efficiently. Since they are placed in a flat position, it will be easy for dust and grime to accumulate in dry climates. Sun-Ways indicates that installing cylindrical brushes under trains is a cost-effective solution.

Snow accumulation is yet another issue. The brushing solution could help, though Sun-Ways also points out that solar panels do not produce as much electricity during the snow season in cold climates due to the lower position of the sun, rendering the snow issue somewhat moot. That’s also another argument for deploying the grid-to-substation model instead of investing in on-site inverters.

Linear Photovoltaics Are Happening

Sun-Ways is working on a first pilot test of its system next year. The company recently received permission from the federal officials to install 48 solar panels extending 100 linear meters on a working railway line starting at Buttes in the canton of Neuchâtel, Switzerland. The installation is expected to produce 16,000 kilowatt-hours per year, which will be shunted to a local GRD.

Hold onto your hats. Sun-Ways also notes that a selection of additional pilot projects is also under consideration for locations, potentially including France, Spain, Romania, South Korea, China, Thailand, Australia, and the United States.

As a side note, if you caught that thing about linear photovoltaics, that term is new to the pages of CleanTechnica. I’m reaching out to Sun-Ways for more details. In the meantime, if the idea is to establish some sort of clean energy hub it could be a reference to the fuel-agnostic, compression-based Mainspring Linear Generator recently introduced into the market by the California startup Mainspring Energy.

Last year, IEEE Spectrum published an article by Mainspring co-founder Matt Svrek indicating that the generator can supplement solar panels and wind turbines with other types of non-fossil fuels when the weather is not cooperating. Ideally the alternative fuels would include green ammonia and green hydrogen sourced with renewable energy as well as biogas, though the generator can also run on conventional fuels.

“One real-world example of the system working this way pairs our generators with a 3.3-megawatt rooftop solar array. When the sun is shining, our generators turn off, and when the sun goes down or goes behind a cloud, our generators automatically turn on within seconds, immediately providing precisely as much power as the building requires,” Svrek explained.

Another example of the system at work is the new electric truck charging microgrid established by Maersk and Prologis at the Port of Los Angeles, where space constraints do not allow for on-site solar panels with energy storage. The facility is designed for 96 charging ports with a capacity of 300 trucks daily.

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Image: The Swiss startup Sun-Ways is piloting an ingenious new system for hiding large arrays of solar panels in plain sight, in between the ties of railroad tracks (courtesy of Sun-Ways).