First Solar Roadway Opens in Idaho

October 5, 2016 | Comments

In the small town of Sandpoint, Idaho, the roads are receiving a re-pavement like no other. Instead of petroleum-based asphalt, cars will now drive over an electrical grid of solar panels. According to engineer Scott Brusaw, Sandpoint is the first municipality in the U.S. to take this ambitious leap into the renewable energy sector.

Brusaw is the founder of Solar Roadways, an electrical engineering company that first demonstrated its prototype in 2010. Little did the engineering team know that its design would eventually garner $2.2 million dollars in crowdfunding and gain so much attention that President Obama would mention the company in a State of the Union speech.


Scott and Julie Brusaw stand next to their solar panel prototypes in Sandpoint, Idaho, where Solar Roadways is based. (Image courtesy of Solar Roadways.)

Last Friday was the official launch of the solar roadway design. From the futuristic look and colorful display of the roadway, it is clear that the small start-up has come a long way in the past six years. But will the design prove itself worthy of the investment?


Every Successful Engineering Design Has Its Prototype

It all started in 2010 when Brusaw videotaped a concept design of a solar panel roadway in his friend’s garage. Afterward, representatives from the U.S. Department of Transportation took notice and granted him $100,000 in the Small Business Innovation Research award.

Moving forward with its prize, Solar Roadways built the first prototype—a 12 ft x 12 ft road panel and a 3 ft x 3 ft crosswalk panel with load sensors that can identify car and pedestrian motion.


The weight of two pedestrians on a crosswalk panel triggers a warning message in front of them. (Image courtesy of Solar Roadways.)

The solar panels have the ability to communicate with each other and have their own grid of LED lights. This allows the solar panels to send signals containing vital traffic information to other panels up ahead of them—triggering the LED lights to display messages to oncoming drivers.

To learn more about the beginning phase of the solar roadways, see the video below.

The first prototype showed promising results in terms of functionality, but there were still many drawbacks. For instance, the panel was way too large, so further design alterations needed to take into account mobility and ease of maintenance.

Several years later – and millions of dollars more in funding provided by awards and crowdsourcing – the electrical engineering team made some significant improvements to its design.


Further Down the Road…

While the main specs of the solar roadways remained primarily the same, the shape and size changed to incorporate more solar cells and make the panels easier to transport. Each panel weighs less than 100 lb, and it should now be easy enough for a single operator to go in and replace.

Naturally, one would be concerned that a broken solar panel would cause a major traffic disruption. The system is engineered so that operators can program the LED lights to redirect traffic while a solar panel is being replaced, meaning construction road workers wouldn’t have to attend the sight to reroute traffic during repairs.


Prototypes of the latest design of solar roadway panels. (Image courtesy of Solar Roadways.)

The solar roadways have a microprocessor every 2.5 ft, which allows the solar panels full capability to communicate with each other and report issues to a central control station.


Solar Panels with Glass Are More Sturdy Than They Sound

The solar panel components of the road are made with tempered—or safety—glass. The same type of glass that can withstand bomb explosives. Through a series of tests involving trial and error, the engineering design team states that the glass should have a comparable strength to asphalt.


A before and after demonstration of the panel glass. The equipment used included a CNC machine for glass, a kiln, a CO2 laser and a reflow oven. (Image courtesy of Solar Roadways.)

Roadways are notorious for reaching extremely high temperatures in the hot sun. At this stage, each panel—as well as the electronic components inside of them—is capable of withstanding temperatures between -40 °F and 257 °F.

The panels are hermetically sealed so that they can function in all weather conditions—and can even be submerged under water.

Other safeguarding mechanisms include protective diodes, which shield against bursts of electromagnetic pulses that may occur in the event of a nuclear detonation test or a sudden fluctuation in the magnetic field. During such an event, the diodes transfer the burst of energy through a low-impedance path around any low voltage circuitry and into the ground.

A series of virtual and physical loading tests has shown that the solar panels are capable of handling trucks that weigh up to 250,000 lb—well above the 80,000 lb that is the maximum legal limit for a semi-truck.


New Visibility Opportunities for Roadways

The solar roadways will come complete with an array of LED lights that are capable of displaying up to 16 million different colors and providing the ability to customize the roadway design. This effectively eliminates the need for road paint and introduces a whole new system for road signage.

First choice

Look familiar? The LED lighting is capable of displaying colors in white, yellow, red, green and blue. Drivers can actually drive on rainbow roads. (Image courtesy of Solar Roadways.)

The design team at Solar Roadways is clearly aware of the enormous opportunities this provides—from added warning signs of oncoming emergency vehicles to parking lots that can change to accommodate more drivers.


In a demonstration video, the solar panels shine a bright red to warn cars of an oncoming fire truck. (Image courtesy of Solar Roadways.)

A parking demo shows how making parking lots customizable can open up spaces for those who need it most.

One of the biggest advantages of incorporating LED lights to roadways is that it certainly would improve visibility. The Solar Roadways website references a study in the UK where LED studs were built onto a stretch of road, and as a result, nighttime accidents were reduced by 70 percent.


Possibly Paving the Way to the Future

Solar Roadways has received more than one award from the U.S. Department of Transportation, and it has gained lots of positive international attention. It is not surprising as the team is bravely treading new waters in the solar industry. Despite all the hard work that has been put into this, though, I can’t help but want to bring to light some uncertainties I have about this project.

The Ground Changes: Whether it’s from sudden tectonic movement, land subsidence from groundwater depletion, soil erosion after a heavy rainfall, or movement from freeze-thaw cycles, the ground does shift. And glass panels are not exactly the most flexible road pavement material.

If I were the head of Solar Roadways, I would not deploy the panels on a road network unless I had sufficient environmental data showing that the ground had little chance of dramatically shifting in the future.

Hill Curves and Crests: The solar panels are 4 ft2 hexagons, and the company states that the panels can easily be fit to accommodate the 3 percent crown that roads have to divert storm water. As for more pronounced curves, it simply states that future designs will try to incorporate more structural flexibility. This adds to the same concern as before, that the rigid glass panel design does not bode well in the variable, rural road landscape.

It is without a doubt that if these solar panels were protruding out in the middle of the road—it would present an enormous problem. It may compromise the structural integrity of the design, not to mention create a headache for snow plowers.

Life Span: According to the company, the life span of the solar cells is between 20 and 30 years. The limiting factor is apparently not the durability of the panels but the fact that solar cells lose their efficiency toward the end of their life cycle.

From a common sense standpoint, it just doesn’t seem sustainable to replace roads every few decades. There is also the issue of efficiency. The general rule of thumb is that solar panels lose around 1 percent of their efficiency ever year, and they tend to lose efficiency faster when they are more exposed to weathering. But what about the physical stress caused by thousands of cars driving over them every day? Will they really still have 80 percent of their powering capabilities after 20 years of this treatment?

Perhaps time will tell. Last Friday, 30 solar panels were put into commission in Sandpoint, Idaho. Whether or not the idea will move forward will likely be determined by how well this cluster of panels functions. To learn more about the technical specifics of the roadway panels, visit the Solar Roadways website.


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