Science & Technology

The World's First Solar Road Explains Why We Don't Have Solar Roads

It seems like a no-brainer: we have solar panels. We have millions of miles of road. Why not cover those roads with solar panels and fix our energy problems for good? Well, France just tried that. Turns out that solar roads aren't the miracle you'd think they are.

Wattway By The Numbers

The new test road, called Wattway, makes up a single lane that stretches 1 kilometer (0.6 miles) through the village of Tourouvre-au-Perche in France's Normandy region. Over its two-year test period, it's expected to be used by roughly 2,000 drivers every day. The cutting-edge roadway cost €5 million, or roughly $5.4 million.

So what about its energy-generation stats? It's covered in 2,880 photovoltaic panels, which are projected to produce 280 megawatt hours (MWh) of energy each year and an electrical output of 767 kilowatt hours (kWh) per day. How much electricity is that, you ask? It's enough to power...wait for it...the streetlights.

You might be surprised to learn that Wattway's big claim to fame is how inexpensive it is compared to alternative plans. Each panel is extra thin and designed to be installed on top of roads that already exist, so it saves money in construction costs. Still, that €5 million price tag is just for the initial cost — it doesn't include future maintenance, and how well the solar panels will withstand the pounding of thousands of cars each day is an open question.

Why Solar Roadways Aren't Worth The Effort

According to Ars Technica, "their questionable efficiency is one of the main reasons that more solar roads aren't currently being built." The efficiency of Wattway's solar cells is purportedly 15 percent, which sounds low until you realize that most rooftop solar panels only hit about 20 percent.

But, Ars Technica continues, "that doesn't take into account the fact that the solar panels are flat on the ground, rather than angled towards the sun's trajectory, significantly reducing efficiency at higher latitudes. Heavy traffic could also block sunlight; as could snow, mud, and perhaps standing water after rain." Add to that the exorbitant cost and the questionable amount of maintenance, and you start to wonder if solar roadways are more trouble than they're worth.

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Written by Curiosity Staff February 9, 2017

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