You have probably noticed this video making its rounds on social media. In the video you are introduced to the Julie and Scott Brusaw, the creators of Solar Roadways. It goes through how beneficial they could be for the economy and the environment and is a very entertaining video to boot. When I first watched this video, I was all about this idea. How cool would it be to jump start the economy with a huge infrastructure project like this?!
However, as Dave from EEVblog and Thunderf00t explain, many of the claims in the Solar Freakin’ Roadways video are unsubstantiated, untested, or even implausible. For example, Scott Brusaw claims we will run out of asphalt in 50 years because it comes from fossil fuels. Except asphalt is the most reused material with over 99% of removed asphalt getting reused.
The Brusaw’s have not produced any stop tests on this surface with vehicles traveling at real-world speeds and conditions. How will wet conditions affect the stopping distance on these solar roadways? No one knows because no one has performed real-world tests.
Roads are dirty. There’s no avoiding that. But what is going to happen to the glass surface when relatively hard dirt (usually small quartz grains) is driven on top of over and over again? It’s going to scratch the glass, making it less transparent (therefore allowing less light through, lowering the efficiency of the solar panels), wearing away the textured surface. Check out the pictures of their proposed that surface:
Solar Roadway Surface
It looks knobby, almost like bubble wrap. Imagine what driving over that at 50 miles per hour would sound like! It would be loud – kind of like driving in a Jeep Wrangler with knobby tires or driving in the rumble strip of a highway. The sound alone, I think, is enough to keep this idea on the drawing board.
Thick glass will lower the solar panel output and make the LEDs really hard to see in broad daylight, especially when you consider the low angle at which they’ll be viewed. Speaking of angles, a solar roadway would be lying flat on the ground, not facing toward the sun. This lowers the efficiency of the panels by up to 18%.
According to one calculation, the cost for replacing all of the roads in the lower 48 states would be $56 trillion, that’s over 3 times the United States’ GDP.
A different company, SolaRoad, has installed a 230-foot prototype solar pathway in the Netherlands. This solar pathway was featured in numerous mainstream media sources, including Popular Mechanics. It has been active for six months and the data are in: it produced more energy than originally thought! But wait… what does that mean, exactly?
As EEVblog’s video explains, not that much. As it turns out the pathway did not produce any more electricity than a similarly sized rooftop solar array. In fact, a rooftop solar array would have TWICE the output per area of a solar pathway at a fraction of the cost and inconvenience.
So what should we be putting our time and resources toward?
The short answer: above us, not below us. There are many advantages to putting solar panels on top of parking lots like some stadiums and colleges are doing. South Korea put solar panels above a bike lane that is located in the median of a major highway as shown below:
Korean Solar Highway
The Bottom Line
Putting solar panels under the road makes no sense at all and will never be more efficient than putting panels on a roof. There are just too many disadvantages – both physical and financial – in building roadways (or bike paths) out of solar panels. Back to the drawing board with this one.