Case study of
#00142 Embed photovoltaics directly into the running surface of roads and paths
Tourouvre-au-Perche, Normandy, France
#00141
Implementer
Colas (Bouygues subsidiary) with the French National Institute for Solar Energy (INES)
Timeline
Dec 1, 2016 – Jan 1, 2019
Location
Description
Colas opened a ~1 km "Wattway" solar road (~2,800 m² of resin-encapsulated PV cells bonded onto an existing road surface) in Tourouvre-au-Perche, Normandy, in December 2016, co-developed with the French National Institute for Solar Energy (INES) and backed by French state subsidy. Performance fell far short of projections: designed for ~767 kWh/day, it delivered roughly half that. The surface deteriorated under traffic, weather, and delamination — including loose fragments and storm damage — to the point of being dismantled by early 2019. Colas subsequently pivoted away from road-surface PV toward powering isolated roadside equipment (signage, sensors) in off-grid locations.
Metrics
3Funding
Lessons learned
- Bonding PV onto a trafficked road couples the panels to pavement wear, delamination, and storm damage that rooftop and ground-mount arrays never face — the best-resourced pilot still failed, isolating the problem to the concept rather than execution.
- Equivalent panels installed beside the road would have produced more energy at a fraction of the cost (~8.5× rooftop PV per watt, ~360× conventional asphalt per m²); the opportunity cost is a core reason to reject the road-surface format.
- The only surviving commercial niche after this pilot is tiny off-grid loads (powering roadside sensors/signage), not grid-scale generation.
Documented Jul 13, 2026
History
· 1Arnaud Gissinger · 5h ago · approved by Arnaud Gissinger 5h ago