TOUROUVRE (France) • France has inaugurated the world's first "solar highway", a road paved with solar panels providing enough energy to power the street lights of the small Normandy town of Tourouvre.
The 1km "Wattway" - covered with 2,800 sq m of resin-coated solar panels - was hooked up to the local power grid as Environment Minister Segolene Royal looked on.
"This new use of solar energy takes advantage of large swathes of road infrastructure already in use... to produce electricity without taking up new real estate," Ms Royal said in a statement.
The minister announced a four- year "plan for the national deployment of solar highways", with initial projects in western Brittany and southern Marseille.
An average of 2,000 cars use the road in Tourouvre each day, testing the resistance of the panels for the project carried out by French civil engineering firm Colas, a subsidiary of construction giant Bouygues.
The idea, which is also being explored in Germany, the Netherlands and the United States, is that roadways are occupied by cars around only 20 per cent of the time, providing vast expanses of surfaces to soak up the sun's rays.
HOW THEY WORK
Interlocking Wattway solar panels are glued on the existing road surface. Each panel is a few millimetres thick and comprises 15cm-wide polycrystalline silicon solar cells that are coated in several layers of protective resin and polymers that are clear enough for sunlight to pass through but strong enough for a truck to drive on.
The surface has a special coating that provides the same grip for tyres as normal asphalt. The system is designed like a watertight layer cake that keeps on generating electricity even if some cells are damaged.
The aim is to create more Wattway-covered roads, carparks and driveways. The firm that makes the system, Colas, says Wattway can be used to power street lights, households and charging for stationary electric vehicles.
Colas says that in theory, France could become energy independent by paving only a quarter of its million kilometres of roads with solar panels. Sceptics are waiting to see whether the panels can withstand the ravages of time and weather, as well as the beating from big trucks.
Solar panels installed on a 70m stretch of a cycling lane north of Amsterdam experienced some damage last winter but the problem has been resolved, the project's company TNO said.
The Wattway project, which has received a state subsidy of €5 million (S$7.6 million), began with four pilot sites around France, in parking lots or in front of public buildings, on much smaller surfaces of between 50 sq m and 100 sq m each.
One drawback of the system is that solar panels are more effective when angled towards the sun, typically on slanted rooftops, than when they are laid flat.
And the cost question is far from being resolved. Each kilowatt-peak - the unit of measure for solar energy - generated by Wattway currently costs €17, compared with €1.30 for a major rooftop installation.
But Colas hopes to make the cost competitive by 2020, noting that the cost of producing solar energy decreased by 60 per cent between 2009 and last year, according to French renewable energy association SER.