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Solar Roads: Misfits of the Solar World

Updated: Jun 19, 2023

Solar-based technologies are finding applications in virtually all aspects of life, providing alternative energy solutions and widening the range of options available to us. We've covered solar air-conditioners, solar car chargers, solar generators, solar water pumps, solar laptop chargers, solar water heaters, solar freezers, solar streetlights, solar roofs, etc. This article will cover a solar energy solution that is considered a failure of epic proportions. For now.

A solar roadway is a road surface that would convey both motorized traffic while producing electricity in the typical way, that is, from sunlight. Technically, a solar road is a road that is made of solar panels.

A Brief History of Solar Roads that Lead Nowhere

1. The Wattway

The first attempt at a 'solar road' was announced in 2014 and opened in 2016 in the small village of Tourouvre au Perche in Normandy, France. Fashionably named 'Wattway', it was received with viral fanfare and was hailed as the “world’s first solar road”. It cost $5.2 million on 0.6 miles of road, and 30,000 square feet of solar panels.

At the opening of the trial road built by French civil engineering firm, Colas Group, the French minister for energy said she looked forward to having solar panels on one mile of road every 621 miles in the country within the next five years. The project was meant to produce about 150,000 kWh a year, that is enough power to provide light for up to 5,000 people, every day. Colas said that the panels were covered with resin containing sheets of silicon to make them capable of withstanding all traffic.

But by May 2018, more than 300 feet of the road had to be demolished due to irreparable damage with much of the rest degraded, peeled away and splintered. Less than a quarter of the energy targets were met and the French government had to abandon plans to pave 1,000km of roads with solar panels.

Segolene Royal, French Minister for Environment at the inauguration of the Wattway in 2016. Source: Benoit Tessier/Reuters
2. Solar Roadways.

The idea of a 'solar road' dates further back to 2006 with the founding of the company Solar Roadways by American couple Scott and Julie Brusaw. Solar Roadways proposed a system that would require the development of strong, transparent, and self-cleaning glass with the necessary traction and impact-resistance properties at competitive cost. They even envision that their roads can 'protect animals' from road accidents, is 'impervious to potholes' and can provide 'emergency warning systems'.

By April 2014, the company had raised $2.2M from the crowd-funding platform Indigogo, that was aided mostly by the hype with which their plan was received. In 2016, the company first installed their hexagonal in a town square in Idaho despite severe criticism of the idea by scientists and public analysts. Just two years later, their town square installation had to be abandoned.

Solar Roadways, in an all-American spirit, promised an even more grandiose solution to the global energy crisis. They promised panels that would light up the roads with different LED patterns, replacing painted lines. Their roadways would also carry heating coils that could melt snow and ice during the Winter and all the while producing electricity and requiring little to no maintenance!

Up till today, Solar Roadways remain an idea.

3. The SolaRoadKill

With more modesty, in October 2014, a bike road called the SolaRoad was opened in Krommenie, in the Netherlands. It was 90 m long and 3.5 m wide. It was celebrated in the same fashion as its French counterpart as well as harshly criticized. Considered 'successful' at the time, other new pilots were planned by 2019.

The Solaroad: How it Started

By the next year, multiple problems had started to develop with the project. In fact, by January 2020, a sign warning 'Bad Road Surface' was installed to warn pedestrian. And in 2020, it was eventually closed and abandoned as a failure. The solar panels in the cycle path were removed and the underlying elements were overlaid with asphalt. It was a hell of an irony since the money spent on building the road could have purchased 520,000kW per year of electricity in comparison to the 3,000kW per year that was generated by the bike path!

SolaRoadKill: How It's Going
4. Thieves Stole China's Solar Highway

In December 28 2017, China opened its 1km solar highway in the Shandong province’s capital Jinan, south of Beijing. At 0.6 miles long and touted to produce up to 1GWh every year – enough to power 800 homes, it managed a meagre 6MW of energy in the first four months of operation. The Chinese government had plans to use the electricity created by its solar highway to power street lights, billboards and CCTV cameras, as well as to heat the roads surface to melt any snow that gathers on it.

By January the following year, 2018, just five days after the road was opened, per an LA Times report inspectors found that one six-foot panel had been stolen by. The thieves also damaged seven surrounding panels.

The Chinese daily, the South China Morning Post reported that a local investigation had concluded that the solar highway was 'a victim of poor design.' But it did not matter as the road fell to the same fate as other solar roads: in an eventual closure.

Source: XinhuaNet
A Rare Success That May Mostly Likely Become Another Laughingstock

In December 2020, the City of Peachtree Corners in Gwinnett County, Georgia launched a new solar roadway system that produces energy for an electric vehicle charging station at city hall.

Ironically, the makers of Wattway, Colas Group were involved in this project and a second trial project in France. And typically, like the other projectionists, the city is projecting that its solar road could power streetlights and other city infrastructure, as well as back-up for grid outages, etc.

What the Future Holds

The concept of solar roads is not going anywhere. For both good and bad reasons. One of the good reasons is that there have been worthy lessons from these failures and solar roads promises to solve some if not all of the world's problems. But these failures have laid bare major technological and even logical constraints that cannot be possibly ignored:

One, the cost of construction is still insanely high. Per square metre, bitumen/asphalt roads are cheaper than centimetre thick slabs of toughened glass. There is no ecological emergency that says that this will change anytime soon or ever. Asphalt is a mixture of waste products from the refining of oil, and fine gravel or its aggregate. Glass, on the other hand, is formed by melting silica, and requires large amounts of energy to produce. Moreover, the glass used in the manufacture of solar roads that are expected to bear heavyweight for considerably long periods of time is far higher than is used in standard rooftop solar panels. No matter the technological innovation, it will be considerably more expensive than rooftop solar panels. The question is whether the electricity generated from a solar road can make up for this cost. In comparison to rooftop solar, the answer is No!

A Patio Solar Driveway: Solar Roads Could Find an Immediate Application as Driveways that can provide Charging for Electric Vehicles

Two, roads are not oriented to face the sun. Roof-mounted solar panels are actually tilted either against the roof or on the rails in which they are placed. Solar panels are most efficient when they are perpendicular to the sun’s rays since the sun shines at an angle to the earth's surface and unlike the rains which fall vertically, they tend to tilt the panels to degrees ranging from 28–30 degrees to optimize efficiency. Learn more here.

Three, solar panels work best when they are cool. It is likely that solar roads would be forced to operate at higher temperatures due to heat from the ground. This would further reduce their performance.

Four, driving on a glass surface is like driving on ice. Motor vehicles and their tyres are not built to drive on glass surfaces. To successfully retrofit all major roads with solar panels will require a corresponding adjustment to existing tyre-making technologies.

One of the major pitches of solar roads start-ups is that roads present unused surfaces that can be converted into electricity generators while solving all of mankind's problems. But again, it beats the imagination to understand the necessity since in most urban areas, there are more rooftops and architectural surfaces on which solar panels can be installed per square metre than there are roads! In the United Kingdom, the ratio is 17.6 to 2. Excluding the other fanciful features, if the goal is to generate more electricity, covering just a fraction of the UK’s rooftops with solar panels would yield more power than putting them on roads.

Also, roads are at the bottom of cities so it is illogical to place sun-powered devices there.

With the materials and technologies and the basic theoretical and ecological assumptions available to scientists and technologists at this point in human history, solar roads are an absurdity. For now. But they may have a place in the future. Who knows?

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