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Call it Utopian but the idea of having solar-powered roads in India is a truly appealing one. The reason is simple. The country, which has the second-largest road network in the world, is blessed with about 300 days of sunny weather and a government that is convinced about the potential of solar power and electric cars. In 2014, India’s Prime Minister Narendra Modi announced a goal to increase solar power capacity to 100 gigawatts (GW) by 2022. Moreover, it is encouraging the sale of electric cars in the country.

On the flip side, India does not have enough electricity to even power all its cities, towns and villages. So even powering electric cars at charging stations is bound to pose a very big challenge. In this context, a solar-powered road that charges electric vehicles on the go does sound like a good idea.

The proposition is definitely not outlandish. In fact, the world’s first solar highway was inaugrated in France, in the not-very-sunny village of Tourouvre au Perche in Normandy. The road was built by Colas, an Anglo-French construction company. According to a press statement, Colas teamed up with the French National Solar Energy Institute to develop the solar highway called Wattway, which is a kilometre long. The project is expected to be used by about 2,000 motorists a day.

Wattway photovoltaic panels are directly applied to existing roads, highways, bike paths, parking areas, etc., without any civil engineering work and can safely bear vehicle traffic of all types, while producing electricity, claims Colas. Each panel contains 15-cm wide cells making up a very thin film of polycrystalline silicon that transforms solar energy into electricity. These extremely fragile photovoltaic (PV) cells are coated in a multilayer substrate composed of resins and polymers, translucent enough to allow sunlight to pass through, and resistant enough to withstand truck traffic.

Colas claims that an average single home (not including heating) can do with a mere 20 m² of Wattway, while 100 m² of Wattway panels can provide enough power for an electric car to travel 100,000 km.

Ségolène Royal, France’s minister of ecology and energy, announced last January that the government intends to pave 1,000 km of road with photovoltaic panels in the next five years, supplying power to millions of people.

However, it was the Netherlands that built the first solar road--a bike path--in 2014. Other companies in the fray for solar roadways include German startup, Solmove, that aims to bring solar panels to German roads, and Idaho-based Solar Roadways Inc., which has received three rounds of U.S. government funding (plus $2 million in venture capital) to test its technology, according to a 22 December report by National Geographic .

Exciting as solar roadways may sound, there are many challenges on that path. For one, a little above 60% of Indian roads are paved. Second, the cost of building a solar roadway is exorbitant—just a kilometre of the Normandy road, for instance, cost around 5 million Euros. Third, while the Sun is undoubtedly the greatest sustainable energy source on earth, the problem is the low efficiency—80% of installed PV panels worldwide have a performance of 15% or lower. Fourth, solar panels can be stolen in India. Last, but not the least, Indian municipalities suffer from a lack of coordination when it comes to incessantly digging up roads.

To be fair, India has explored the utility of solar roofs. After setting up canal solar power projects, scientists at the Gujarat Energy Research and Management Institute (GERMI), in April 2013, proposed a pilot solar power project at a Gujarat state highway. But nothing much was heard about the project after that.

That said, as prices continue to fall, solar energy is increasingly becoming an economical energy choice for homeowners and businesses. A 28 January, 2016, note by Peter Harrop, chairman of research firm IDTechEx Ltd., points out that while “installing photovoltaics in roads seems a daft idea at first...a closer look reveals that most of the problems are easily overcome..."

Harrop concludes: “At IDTechEx we do not see solar roads replacing power stations: do that with a field full of solar panels not transmission and maintenance over long distances. However, they could be excellent for dynamic (in-motion) charging of electric vehicles possibly coupled with roadside wind turbines or tethered multicopters providing Airborne Wind Energy, AWE in the new jargon."

Cutting Edge is a monthly column that explores the melding of science and technology.

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