The small town of nearly 3.400 inhabitants located in Normandy (Tourouvre-au-Perche) has enjoyed, since December 2016, a one-kilometre-long solar road. This is the largest infrastructure of its kind in the world, and is part of the project wattway. Its installation was inaugurated by the then Minister of the Environment, Ségolène Royal, and has become a benchmark in the French energy transition.
The implementation of solar panels on roads is not a new idea. In fact, it emerged more than a decade ago in the United States, and since then there have been experiments in cities such as Amsterdam and Berlin. However, until the arrival of the Wattway project, these implementations were on a considerably smaller scale, limited to roads of a few meters. Wattway has brought a new dimension to this concept, by covering Sqm 2.800 with photovoltaic panels integrated into the pavement.
The Wattway Project: Development and Implementation
The Wattway project has been led by the public construction company COLAS (belonging to the Bouygues group), in collaboration with the National Institute of Solar Energy (INES), the Commission for Atomic Energy and Alternative Energies (CEA), and the University of Savoy. After five years of testing and research, it was finally decided to implement a large-scale pilot test on the Tourouvre-au-Perche road. Preliminary tests were carried out in different locations in France, such as Vendée, Bouches-du-Rhône and Yvelines.
The solar section installed in Normandy uses photovoltaic modules manufactured by the cooperative SNA, located in the same town. According to the engineers behind the project, the technology used in these panels is capable of resisting the passage of vehicles of all kinds, including those of large tonnage. One of the keys to their durability is the protective resin that covers the solar cells, which also guarantees adequate adhesion for car tires.
Operation and benefits of solar pavement
The operation of the solar road consists of capturing the sun's energy through solar panels integrated directly into the pavement. The electricity generated is fed into the local distribution network, and it is estimated that an area of ​​20 square meters is sufficient to power a home (not including heating). In the case of the Tourouvre-au-Perche road, it is expected that the energy generated will be able to cover the consumption necessary for the Street lighting of the commune.
One of the main advantages of building a solar road is that it uses an existing space to generate energy, thus avoiding the use of arable land. This feature is key if we consider that traffic on roads only occupies about 10% of the total time, leaving a large surface available to capture solar radiation.
Furthermore, COLAS It is estimated that the maintenance cost will be low compared to the long-term benefits, given that photovoltaic cell technology is constantly evolving, making them more efficient and durable.
Criticisms and challenges facing the project
Despite the promised benefits, the project has been the subject of numerous criticisms, mainly due to its high costs. The construction of the solar road section in Normandy cost 5 millones de eurosCritics point out that such a large investment could have been spent on more energy-efficient infrastructure, such as tilted rooftop solar arrays, which would also be cheaper to build.
Another important point of discussion has been the Energy Efficiency The project's production capacity was initially announced at 790 kWh per day. However, a few months after its launch, this figure was reduced to just 50%. According to experts such as Marc Jedliczka, vice-president of the Network for Energy Transition (CLER), the project's methodology was not well calculated, as the Normandy region is not particularly known for its high solar radiation.
Over the years, other technical problems have been detected. For example, the photovoltaic pavement has been reported to have suffered unexpected wear and tear, with fallen leaves and thunderstorms negatively affecting the surface of the panels. These problems have significantly reduced energy production to 37.900 kWh annually in recent reports.
A project with an uncertain future
Despite the criticism and problems, proponents of the solar roadway maintain that it is an innovation with enormous potential for the future. Although the cost per watt generated is currently around 17 euros (compared with just 1,3 euros for conventional solar installations), those responsible for the project are confident that costs will fall as the technology continues to advance. They are also planning optimizations that will allow the energy efficiency of the panels to be improved in non-ideal conditions.
The Wattway project is still in the testing phase, and the information gathered over the next few years is expected to be crucial in determining whether solar road infrastructure can aspire to become a viable and sustainable solution for large-scale renewable energy production.