How Solar Panel Highways Work

The U.S. has a network of roads all over the country. Why not place panels along the roadways as sound barriers? Or, here's an even more extreme idea: why not make the roads themselves out of solar panels? This has now been accomplished.

A solar roadway consists of individual solar road panels with three layers: a top layer of high-strength, textured glass that provides traction for vehicles, an array of solar cells beneath that for gathering energy, and a base plate that distributes the collected power, according to Solar Roadways.

They're more than just solar energy collectors, too. The panels contain LED lights, powered by the sun, that can act as road and warning signs built into the road itself. In addition, they can use gathered heat to melt snow and ice on the roads.

Though a few different companies, in a few different countries, have attempted solar roads, many of the initial concerns have proven to have merit. For example, flat solar road panels are less effective at capturing sunlight than tilted panels. Shade over even a small portion of the panel drastically reduces efficiency.

Dust, debris, a lack of air circulation on the surface, and the thick glass coating necessary to help the panel withstand traffic can also reduce a panel's effectiveness. Furthermore, that glass surface doesn't provide the kind of traction that drivers are accustomed to.

The Solar Panel Experiment in Normandy

Here's what went wrong in the quest for durable and efficient solar power, as illustrated largely by the solar road in Normandy, France. The plans for the solar road in Normandy were announced in 2016, but after three years of use, the experiment was declared a failure. The plans called for a stretch of about 620 miles (1,000 kilometers), with the goal of generating enough power for 5 million homes, writes Big Think.

The first stretch of road completed was just over half a mile long and was expected to power up to 5,000 homes, but it became clear rather quickly that expectations would not be met. The solar panels became damaged more quickly than expected, due to wear and tear caused by traffic and weather. Even at peak efficiency, the panels proved to be less effective at generating clean energy than regular, tilted solar panels, like rooftop solar panels or those commonly mounted alongside the road (rather than on it).

Though Normandy is probably the biggest example of a failed solar roadway experiment, there are others. Along a road in China, a solar panel was stolen, leading to the project's cancellation. In Missouri, the solar panel company and the government failed to reach an agreement on a planned project. Even so, green energy plans are constantly being formulated in these areas, trying to offset climate change and our reliance on fossil fuels.

Though the excitement seems to have slowed overall, some projects are still underway. A lab in Atlanta, Georgia, for example, maintains that the merits of a solar roadway are still worth exploring. As of February 2019, an 18-mile stretch along Interstate 85 is still in use.

Experts at the Ray C. Anderson Foundation hope that future versions of solar roads can charge electric vehicles and, thanks to its LED lights, self-illuminate the road surface to help drivers see. Furthermore, newer versions of the solar panels are more durable and provide better traction. Using far thicker glass and heating plates, these newer solar roads can generate energy and melt ice better than traditional asphalt or conventional panels.

The foundation says it's better positioned financially to work on unproven technology. This is because the state or federal departments of technology would have a harder time justifying the use of taxpayer funds to continue investing in a project that has already failed to meet expectations. So what kind of unproven technology could that include? A solar power plant?

So whether or not solar roads will be viable remains to be seen, but not everyone is ready to give up on the idea. The need for renewable energy and the promise of solar technology remain too great!