Since last December, the small town of almost 3400 inhabitants located in Normandy (Tourouvre-au-Perche), has enjoyed a one-kilometer-long solar road, the largest of its characteristics in the world. The facility, which has been inaugurated by the Minister of the Environment, Ségolène Royal, aims to be a benchmark in the energy transition.
The idea of deploying solar panels on roads in order to generate electricity is not new. The first initiative of this type emerged more than ten years ago in the United States and, since then, similar projects have been developed in cities such as Amsterdam or Berlin. But to date they were solar paths of a few meters. According to several French media, the Wattway project has brought a new dimension.
Led by the public construction company COLAS (Bouygues group) and the National Solar Energy Institute (INES), with the participation of the Atomic Energy and Alternative Energies Commission (CEA) and the Univserdiad de Savoie, Wattway has materialized after five years of research and tests carried out in the Vendée, in Bouches-du-Rhône and Yvelines, although the real test bed will be the path itself.
The solar road has about 2800 m2 of photovoltaic solar panels in the form of tiles glued to the asphalt and strongly protected by a protective resin that, according to the Wattway partners, “makes them capable of withstanding the flow of all types of vehicles, including vehicles. heavy vehicles ”, while ensuring good grip between the tires and the road. These modules have been manufactured by the SNA cooperative, located in Tourouvre-au-Perche; that is, in the same town that houses the new path.
The electricity generated will be injected into the local distribution network through a direct connection. According to COLAS, a surface area of 20 m2 of the track is sufficient to supply electricity to a home (excluding heating). It is estimated that it will generate clean energy to provide electricity to the public lighting of the aforementioned Norman commune (3.298 inhabitants).
Criticisms of the French solar highway
This unusual project, financed by the French administration, cost 5 millones de euros. But before mentioning the criticism received, let us point out some points to keep in mind about these energy generating routes:
- The biggest advantage of a solar driveway is that it avoids the use of arable land to produce electricity. With it, it would be contributing another utility to the highways.
- The world demand for energy is going to multiply x2 by the year 2050.
- Roads are only occupied by vehicles 10% of the time.
- You also have to consider the constant evolution of photovoltaic technologies, making solar cells more efficient and cheaper to manufacture.
There were few criticisms received, mainly related to the high costs of this solar project. Admittedly, this budget was foreseeable, since getting a photovoltaic flooring resistant to truck traffic makes the work quite expensive.
Its Energy Efficiency , since with that money a solar plant with inclined panels could have been installed. Its location is also questioned, as there are places in France with the highest number of hours of sunshine per year. Here it should be noted that the cooperative in charge of producing these modules is precisely in Tourouvre-au-Perche.
The truth is that although last October the Ministry of the Environment announced that the production of the infrastructure was going to be 17 kilowatt hours (kWh) per day, shortly afterwards it had to rectify and indicate that the expected production is 963 kWh per day. That is, twenty times less.
Experts do not question this technological innovation per se. But they wonder about its performance, and believe that this budget could have been invested in other renewable infrastructures with proven profitability.
A solar driveway made up of Wattway panels
This Normandy road is capable of capturing solar energy and producing electricity for local use. For its construction a special solar pavement called wattway, which withstands heavy vehicle traffic. It is a patented photovoltaic floor that required five years of research and development. Behind him are the Colas company and the National Institute of Solar Energy.
According to its manufacturer, 20m2 of Wattway slabs are enough to supply a home.
These photovoltaic panels acquire great resistance because they are made of a resin with several layers of silicon. In other words, photovoltaic cells are inserted between thousands of layers of resistant material. Its thickness is a few millimeters, it guarantees the adherence of the tires, and it admits the deformations that changes in temperature can cause on the road.
Another interesting point of this material is found in its installation: it consists of plates that are installed directly on the existing pavement.