Are solar roads worth the investment?

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From wearable technology to portable chargers, solar energy is changing the way people power their everyday lives. One of the newest innovations in solar power, however, could literally pave the way to 100 percent energy-efficient cities: Solar roads.

Solar roadways are being tested in various parts of the world, but skeptics question whether the technology is worth its cost.

Solar roads are not new

While the idea of solar powered streets might seem like something out of a futuristic film, the technology is in practice in areas of Europe and Asia.

In 2014, a popular concrete bike path in Amsterdam was embedded with crystalline silicon solar cells to generate electricity. The path’s panels, covered by rubber and tempered glass, underwent five years of testing and can withstand 12 tons. While the original embedded path stretched just 230 feet, it generated enough electricity to power a small household for a year. After three years of continued testing, the SolaRoad creators will consider expanding the technology to other areas of the Netherlands.

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China, the current global leader in solar energy, is also experimenting with solar roadways. Considered the “world’s first photovoltaic highway,” a 1 kilometer stretch of expressway in Jinan positions a layer of solar panels between a bottom layer of insulation and a top layer of transparent concrete. The roadway, which includes two lanes and an emergency lane totaling an area of 63,200 square feet, is said to be able to generate one million kilowatt hours (kWh) of electricity in a year for nearby street lights, snow-melting systems and EV charging stations.

While the Jinan highway has been successful in its goal of power generation, the project has faced a couple of roadblocks. First, the solar road’s steep price tag of $458 per square mile means expansion will be slow. However, its price does not compare to the highway’s unforeseen problem: thieves. Less than a week after the road opened for testing, inspectors found that one of the embedded photovoltaic panels had been stolen, and seven more had been damaged by a professional team of robbers.

Challenges facing solar road technology

Highway robbery isn’t the only threat to solar roadways; some experts argue the cost of installation and maintenance of roads embedded with PVs outweigh their perceived benefits. In fact, many energy experts claim the technology is unnecessary, instead purporting that solar farms will always be more cost-effective and more energy-efficient.

The most common critique of solar roads is the position of the embedded panels. Traditional, above-ground solar arrays are built to follow the sun’s course throughout the day, harnessing a steady stream of energy from sunrise to sunset. PVs embedded in roads cannot tilt to capture the suns light once the sun moves out of the optimal position for capture, which makes them highly inefficient compared with other solar technologies.

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The Amsterdam bike path exemplifies solar roads’ relative inefficiency when considered with cost and energy generation. According to The Guardian, the installation of the solar bike path could have paid for 520,000 kWh of electricity through traditional solar arrays – instead, the path’s embedded PVs generate just 3,000 kWh.

Even with the hefty price tag, solar road technologies continue to appeal to eco-conscious cities. Tokyo, for example, plans on testing solar road installations in preparation for the 2020 Olympics and Paralympics. Still, most green energy experts recommend that cities and governments put their green energy efforts into more cost-effective solar power technologies.

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