A few days before New Years Eve, the capital of the northeastern Shandong province, Jinan, opened the continent’s first solar highway for vehicles. The highway is composed of photovoltaic panels that encompass one kilometer (0.62 mile). The solar highway is expected to handle 10 times more pressure than normal asphalt highways do. It is also expected to generate one million kWH of electricity per year – enough to power 800 homes. The power generated will be used to power street lights and a snow-melting system on the road.

Jinan’s solar highway covers 5,875 square meters (63,200 square feet) and is composed of three layers: transparent concrete on the top, photovoltaic panels in the middle, and insulation on the bottom.

China, the world’s biggest carbon emitter, also ranks first for its usage of solar energy. Since 2013, China was crowned as the world’s biggest solar market, beating Germany as the country with the most photovoltaic installations three years ago. China planned to install a record number of solar power stations in 2017. About 54 gigawatts will be put in place this year, raising a forecast of more than 30 gigawatts made in July 2017. That amount of additional capacity will likely surpass all the solar energy generated in Japan in 2017.

“The amount of rooftop solar plants and projects aimed at easing poverty were more than expected and developers rushed to build some ground-mounted solar projects before they [were] allocated subsidies,” said Yvonne Liu, a Bloomberg New Energy Finance analyst in Beijing.

At around the same time in 2016, Tourouvre-au-Perche, a village in France rolled out what it claimed was the world’s first solar-panel road, running a one kilometer (0.6-mile) route, covered with 2,800 square meters of electricity-generating panels. In 2014, the Netherlands built a bike path embedded with solar panels.

However, some argue that solar highways and roads in general don’t really produce what they’re worth. The Conversation argues that the price of maintaining a solar highway will always keep the technology in the niche market. It also argues that the market will not change since asphalt is a mixture of waste products from the refining of oil and fine gravel or aggregate. However, glass is more energy-intensive since it is formed by melting silica. Bitumen or asphalt roads are cheaper at $5 per square meter in comparison to their solar counterparts at around $15-20 per square meter. (France’s solar highway project, for example, cost a staggering €5 million (a little over $6 million) to build).

Even with the triple price difference, the solar roads are not likely to be as efficient as rooftop solar panel installations. The Conversation argues that roads are not oriented to face the sun. Most roads are at ground level and are easily shaded, so they aren’t engineered to take advantage of most of the direct sunlight. Moreover, as roads are prone to collecting dirt, this will further shade the modules. Photovoltaic panels work best when they are cool; this is why their backing is typically exposed for ventilation. Finally, solar highways and roads are likely to experience higher temperatures due to friction with running wheels, further reducing their performance.

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