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France Wants To Install 1,000 Km Of Solar Roadways Over The Next Five Years

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In 2014, the Netherlands built the world’s first solar bike path, a 70-metre stretch named SolaRoad. The proof of concept performed even better than expected, generating, after six months, enough electricity to power a small household for a year.

Successful and fascinating as it is, the project is very limited in scope compared to the one that is currently in the works in France. The French government has announced that it wants to pave 1,000 Km (621 miles) of road with solar panels over the next five years. The announcement was made by the minister of ecology and energy, Ségolène Royal, during a press conference.

The first tests will begin in spring: according to French infrastructure company Colas, which has developed the photovoltaic road surface (called "Wattway") to be used in the trials, 1-km-long section of road will be able to power public street ligthing for a town of 5,000 inhabitants.

This means that, once the project is completed, the new roadways will be able to supply electricity to 5 million people, or about 8% of the French population.

Colas' technology is innovative, compared to other photovoltaic solutions, in that it does not require to rip out the existing road infrastructure, or make any kind of civil engineering work: Wattway panels are composed of cells inserted, in superposed layers, inside a thin film of polycrystalline silicon which can be applied directly on the pavement.

The cells are encapsulated in a resin substrate, to keep them rainproof, and the composite material is just a 7 mm thick, making it possible to adapt to thermal dilation in the pavement.

There's no indication, right now, of which roadways will actually be covered with Wattway, or of how much exactly the project will cost.

"Wattway’s price per m2 is to be seen in light of the production cost of electricity," the Wattway website explains, "Photovoltaic energy is measured in watt-peak, which takes into account sunlight conditions. Today, depending on the technology used and the support on which the panels are installed, prices fluctuate between 2 to 8 euros/watt-peak. The cost with Wattway is estimated at 6 euros/watt-peak."

Another factor to consider, is the efficiency of Wattway solar panels which seems to be slightly inferior to that of conventional photovoltaic solutions (a 15% energy yield for the former, compared to 18-19% for the latters).

For the time being production times are quite long, as panels are installed by hand, which makes the whole process quite complicated, but in 2016 things should improve a bit: industrial-scale manufacturing is scheduled for launch and Colas' engineers are designing a mechanical process that should optimize application times.

Financial support could come from the government: Ms Royal has proposed to raise taxes on petrol to support to fund improvements to France's transport infrastructure and solar roadways could receive their fair share of the pot.