An average road is used only about ten per cent of the time, which means that ninety per cent of the time, it is just a slap of asphalt (or other material) doing nothing. To make roads functional all the time, the small Norman town of Tourouvre-au-Perche (3,400 inhabitants) now has a departmental road covered with photovoltaic tiles for a length of 1 km (0.6 mile). This project, which is called Wattway and is carried out by the construction company Colas, is unprecedented in the world in size.

On 2800 m2 (3349 square yard), photovoltaic panels were glued to the asphalt, which were then covered in a coating. The silicon sheets are embedded in a protective resin which makes them able to withstand the flow of all types of vehicles, including heavy vehicles, while ensuring good grip between the tires and the roadway. The road will generate about 790 kWh per day, with peaks of up to 1,500 kWh per day during the summer.

The generated electricity joins the local distribution network via a direct connection. According to Colas, an area of 20 m2 (215 ft2) is enough to supply a household with electricity (excluding heating), and 1 km of road equipped provides the equivalent of the consumption of public lighting of a town of 5000 inhabitants.

The idea of deploying solar panels on the road network to produce electricity without taking up space on agricultural land or nature is not new. Over a decade ago, a couple of Americans from Idaho, Scott and Julie Brusaw, opened the way by creating Solar Roadways, which you can read about here and here. Since then, similar initiatives have been launched in several countries, notably in Berlin or the suburbs of Amsterdam. But so far, experiments have been carried out only on very small sections of road.

The concept was executed by Colas and the National Institute of Solar Energy (INES), which combines the Commissariat for Atomic Energy and energy Alternatives (CEA) and the University of Savoy. After five years of research and tests conducted in Vendée, in the Bouches-du-Rhône, and in Yvelines, the Norman solar road will be the real testing ground. The financing of € 5 million was in fact provided by a subsidy from the state.

Photos: Benoit Tessier (via Designboom) / Wattwaybycolas.com