Solar Panels? You're Driving on Them

Jim Motavalli

Jim Motavalli | Dec 21, 2016

If you’re traveling the 18-mile I-85 stretch between West Point and LaGrange, Georgia, you’re forgiven for not realizing your car is on the Ray C. Anderson Memorial Highway (The Ray for short)—though there are signs to that effect.

This solar bike path in Holland is already up and generating power. (SolaRoad photo)

Anderson was the innovative founder of Interface Carpets, which pioneered rug recycling, and after his death (in 2011) the foundation that bears his name is continuing to innovate--with the highway of the future. This very week, the highway is debuting a 50-meter (1,640 feet) section of Wattway drive-over solar panels from France.

“We’re a test site for innovative highway projects,” Taryn Tuss of the Ray C. Anderson Foundation told me. “The Wattway solar panels are a good fit, and the company’s first pilot program outside of France.” Electricity from the highway is directed to a state-run visitor’s center.

An artist's conception of how Solar Roadways would work--complete with programmable LED lights. (Solar Roadways graphic)

“There was competition involved, and we won out over some Silicon Valley locations,” said Allie Kelly, The Ray’s executive director. In addition to its solar panels, the highway also features a drive-through center for tire safety—it measures both tread depth and inflation pressure, and gives motorists a printout—and (soon) a one-megawatt, 3,000-panel solar installation in the median strip. “It’s the first of its kind,” Kelly said.

The French Wattway research is based at the Colas Campus for Science and Techniques, and headed by Jean-Luc Gautier, manager of its Center of Expertise.

Installing Wattway panels: 600 miles of this are coming! (Wattway photo)

Wattway could be the company that breaks this technology big-time since, with the help of the French government, it’s set to install more than 600 miles of solar roadways in France. That’s enough to provide electricity for five million people, eight percent of the French population. Expect it to be in place by 2021.

The concept is pretty simple—electricity-generating, grid-connected photovoltaics built right into the road. There’s an international race, including the American company Solar Roadways Inc., to make this undoubtedly green idea practical. Can you imagine electric cars that don’t even need batteries because they get all their power from the highway surface?

Scott and Julie Brusaw with their magical panels. (Solar Roadways photo)

The advantages are clear, including the ability to heat the road surface and embed changeable messages or lane markings in the road, massively increasing our solar generating capacity. But the big obstacles have been there from the beginning: prohibitive cost, and the need to develop a glass surface that will stay clear, will stay intact through all weather, and won’t crack from the weight of all that traffic. And then there’s the challenge of getting the solar cells to work when covered with snow, ice or sand. Add to that questions about how much traction the surface provides. It’s not impossible, just hard. The Department of Transportation says flat out that we're not likely to see these things coast to coast.

A Wattway installation in France. It's small, but it's a start. (Wattway photo)

In 2011, I wrote a story for the New York Times opining that solar roadways offered a possible—if distant—solution to the problem of electric car range anxiety. Five years later, the situation I described has moved forward somewhat, but we’re still a long way from doing what Solar Roadways envisions—paving every highway and parking lot in the world with this stuff.

Wattway close up: lotsa solar. (Wattway photo)

Solar Roadways, run by Scott Brusaw and his wife, Julie, was awarded a two-year $750,000 Department of Transportation grant at the end of 2015 and is working on freeze-thaw cycling, moisture conditioning, shear testing, and advanced loading—what happens when heavy trucks roll over the panels for years on end. It also raised $2.2 million through a crowdfunding campaign.

Solar lights are one idea for the Ray C. Anderson Memorial Highway--to go with the electric roadway, drive-through tire station and median-strip photovoltaic. (The Ray graphic)

Critics charge (see the video at the end of this story) that Solar Roadways hasn’t said much about the actual generating capacity of its panels.

We have a bit of an answer about how it’s supposed to work from the SolaRoad bike path in Holland. Installed in 2015, the 70-meter (229 feet) path is supposedly generating “enough electricity to power a small household for a year.” Spokesman Sten de Wit said the capacity works out to 70-kilowatt-hours per square meter per year.

A British rendition of how roadway EV charging could work.

Of course, you’re saying—it’s a bike path, how much weight do the panels have to support? But SolaRoad claims its cells (in a sandwich with glass, silicon rubber and concrete) could support 12-ton fire trucks.

Wattway also claims to have the weight-supporting problem licked. “At first, we barely dared to even walk on it,” exclaims Franck Barruel about the development process for its millimeters-thick panels. Wattway has been at it since 2005, but suffered a big setback when its panel supplier (devastated by the glut of cheap Chinese product on the market) went out of business. Now its polycrystalline silicon panels are manufactured locally in France.

Six hundred miles of solar roadways! My guess is that the French will be the ones to provide us with the answer about the practicality of embedding photovoltaics in the world’s roads. The Chinese love stuff like this, so maybe they’ll get involved, too.  

Here's a whizbang video about Solar Roadways:

And here's a skeptical one:

What do you think?


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