Wattway Will Install 1000 km of Solar Roads in France

French infrastructure firm Colas is working with INES (France's National Institute for Solar Energy) on what it calls the Wattway project. In a nutshell, Colas says it has a quarter-inch material that can be glued on top of highway pavement and is strong enough to handle trucks in heavy traffic. The stuff is made out of crystalline silicon, and Colas has been working on developing the product since 2009.

The upshot is that the collaboration is slated to cover about 1,000 kilometers worth of roads with Wattway, and Colas says each kilometer of solar surface will supply enough juice to power 5,000 homes. That means those 620 miles could theoretically be good for about 3.1 million households. In other words, almost 10 percent of all the homes in France right there.

Those numbers should be enough to show that Wattway is a far cry from a competing solar-road construction project, the Netherlands' SolaRoad. That company built a 230-foot ribbon of bike path that was covered in tempered glass and solar panels. That project cost $3.7 million to install, and in the first year generated enough solar power to offset $2,000 in electricity costs. We're banking on a better return on investment in France.

Colas has already gotten local props for the Wattway, winning a "Climate Solutions Award" at the COP21 United Nations Conference on Climate Change in Paris late last year. Granted, a lot of details, such as cost and location of the road top, need to be vetted out, but Colas is saying that tests will start this spring.