Electric avenues that can transmit the sun’s energy onto power grids may be coming to a city near you.

A subsidiary of Bouygues SA has designed rugged solar panels, capable of withstand the weight of an 18-wheeler truck, that they’re now building into road surfaces. After nearly five years of research and laboratory tests, they’re constructing 100 outdoor test sites and plan to commercialize the technology in early 2018.

“We wanted to find a second life for a road,” said Philippe Harelle, the chief technology officer at Colas SA’s Wattway unit, owned by the French engineering group Bouygues. “Solar farms use land that could otherwise be for agriculture, while the roads are free.”

As solar costs plummet, panels are being increasingly integrated into everyday materials. Last month Tesla Motors Inc. surprised investors by unveiling roof shingles that double as solar panels. Other companies are integrating photovoltaics into building facades. Wattway joins groups including Sweden’s Scania and Solar Roadways in the U.S. seeking to integrate panels onto pavement.

To resist the weight of traffic, Wattway layers several types of plastics to create a clear and durable casing. The solar panel underneath is an ordinary model, similar to panels on rooftops. The electrical wiring is embedded in the road and the contraption is topped by an anti-slip surface made from crushed glass.

A kilometer-sized testing site began construction last month in the French village of Tourouvre in Normandy. The 2,800 square meters of solar panels are expected to generate 280 kilowatts at peak, with the installation generating enough to power all the public lighting in a town of 5,000 for a year, according to the company.

For now, the cost of the materials makes only demonstration projects sensible. A square meter of the solar road currently costs 2,000 ($2,126) and 2,500 euros. That includes monitoring, data collection and installation costs. Wattway says it can make the price competitive with traditional solar farms by 2020.

David Fuller's view

Theoretically, this is an interesting idea and an ambitious challenge.  I hope it can be perfected although the overall cost, safety and susceptibility to damage may be too great for existing technologies.  Nevertheless, it shows the incredible adaptability of solar technology, in terms of projects both great and small.   

The sun is the greatest source of energy with which we have any personal experience.  The number of manmade products exposed to sunlight, which can be captured and turn into energy, is practically unlimited.