Smart Roads Go Solar

Innovators test energy-generating roadways.

01 January 2017

Nearly 2800 square meters of rugged photovoltaic panels are being installed on a 1-kilometer section of road surface in the town of Tourouve in northwest France in one of a series of pilot projects aimed at creating energy-generating roadways all over the world.

The Wattway solar panels, built by Colas, a subsidiary of Bouygues, can withstand the weight of an 18-wheel truck. The panels being installed in Tourouve are expected to generate 280 kilowatts of energy at peak, enough to power all the public lighting in a community of 5000 for a year, according to the company.

Other test sites for the renewable-energy roadways will produce electricity for charging electric vehicles, power a small hydrogen production plant, and/or feed electricity directly into the nearby power grid.

The company hopes Wattway will play a major role in building smart roads in the smart cities of the future. Colas has plans to test its patent-pending technology at 100 sites in the US, Canada, Africa, Japan, and elsewhere in Europe during 2017, with the hope of having them ready for commercial use by 2018.

Assuming 1000 sun hours per year, the company says a mere 20 square meters of Wattway panels can provide enough electricity to power an average French household for a year and that 100 square meters of panels can power an electric-car charging station so the vehicle could travel 100,000 km a year.

The PV panels were created in a partnership with INES, the French National Solar Energy Institute. They are extra thin (7-mm-thick) and extremely sturdy, being reinforced with several coatings of plastic composite material to protect the solar cells without blocking sunlight and to adapt to thermal dilation in the pavement as well as vehicle loads.

A layer of crushed glass on top provides vehicles with a good grip on the road surface. The panels are glued directly onto existing roads, bike paths, or parking areas without any civil engineering work.

Each test site for the Wattway panels will be tracked with in situ IT equipment to monitor photovoltaic energy production across a full range of weather conditions and research experts will analyze the data to confirm whether Wattway can withstand all types of traffic.

The tests will also determine whether Wattway can become price competitive with traditional solar farms by 2020. The panels used in electricity-generating roads are more expensive than ones deployed in solar farms, costing about 2,000 – 2,500 euros (US $2,126) per square meter, including monitoring, data collection and installation costs.

However, the Wattway panels take advantage of free space.

“We wanted to find a second life for a road,” said Philippe Harelle, CTO at Colas’ Wattway unit. “Solar farms use land that could otherwise be for agriculture, while the roads are free.”


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