Inventors have created glass-encased solar panels that could be used as a high-tech alternative to concrete pavement. The web of problems that surround the reinvention of the transportation system makes solar roads unlikely anytime soon.

A simple question from a mental health counselor to her electrical engineer husband as they worked in their Idaho garden planted a seed for an idea in 2009. It now seems to be coming into bloom. Concerned about global warming, she asked if he could build solar panels for roads. He assured her that he could not.

However, a week later, he decided that he could invent a glass-encased solar panel as an alternative to the traditional pavement.

Understanding the Concept of Alternative Highways
Their conversation in the garden was the beginning of Solar Roadways®, an infrastructure product that the inventors propose as a replacement for concrete highways, driveways, parking lots, walkways and bike paths. Modular panels contain LEDs that light up messages and create lane lines without paint.

The concept includes the use of microprocessors that send messages to each other and respond to commands from a central control station.

Embedded heating elements are supposed to prevent the accumulation of ice and snow. Designed to charge electric vehicles when long expanses of SR are in place, the invention’s inventors and supporters hope to reduce global warming while generating solar energy for transfer to the electric grid.

The projected capability includes charging electric vehicles while they sit on solar parking lots or on highways at some point in the future.

For the present time, “applications that are not critical, such as driveways and parking lots,” are the first planned installations, according to the SR website. Corridors within the system provide a protected location for power and gas lines and a separate space for water. SR panels have a “tractioned surface which is equivalent to asphalt,” and the company claims that they can “support the weight of semi-trucks.”

Tracking Sources of Funding for Innovative Technology
By attracting interest on a crowd-funding site, the project received contributions of $2,276,088 from more than 340,000 people in 165 countries as of June 2014, according to the IndieGoGo InDemand site.  In a video that co-inventors Scott and Julie Brusaw taped for the website, the couple said that investment money for the fledgling company started rolling in as soon as they established an account.

Contributors receive “perks” in return for donations. A contribution of $25 receives a Solar Freakin’ Flashdrive!, $40 gets a Solar Roadie Key Ring/Opener and a $60 donation merits a Shop/Drive Green tote bag. A hat with hexagons that resemble the shape of a solar roadway unit goes to contributors of $75, and donors of $150 get a Solar Cell Pendant that contains pieces from a prototype. A contribution of $1,000 rewards donors with as many perks as are available, 12 or 13 when supplies allow.

After receiving the first million dollars, the Brusaws knew that their project had potential. With the arrival of the second mil, it was up and running. But the funding effort did not stop there. Phase I and Phase II of funding contracts from the U.S. Department of Transportation (DOT) provided hundreds of thousands of dollars, $750,000 for Phase II alone.

As of November 2015, the project received a third funding contract from DOT. SR has received national and international recognition and awards.

Evaluating Traditional versus Solar Infrastructure Cost

There is no easy way to calculate the average cost per mile of pavement in the United States, but the American Road and Transportation Builders Association suggests a ballpark figure. Prices vary by “location, terrain, type of construction, the number of lanes, lane width, durability” and other factors.

However, cost models from some states show that “construction of a new 2-lane undivided road costs about $2 million to $3 million per mile in rural areas and about $3 million to $5 million in urban areas.”

Contrasting the cost of traditional construction with that of solar infrastructure, Singularity Hub’s article, “ Solar Roadways: Crackpot Idea or Ingenious Concept,” summarizes the math. “Brusaw is aiming for each 12′ by 12′ panel to cost around $10,000 and for the average life span of the panel to be about 20 years. There are roughly 29,000 square miles (~800 billion square feet) of road surface to cover. We need roughly 5.6 billion panels to cover that area. That’s a price tag of $56 trillion!”

Tracking the Progress of European Development Companies

The French transportation infrastructure company, Colas, has introduced Wattway, a photovoltaic road surface. After five years of research, the company has installed it in a small village in Normandy. The process involves “applying it directly onto the existing roadway, without having to redesign the road structure,” according to the Wattway website.

National Geographic reported on three European projects, including the one by Colas for a 1 kilometer (0.62 miles) stretch of a single lane on a two-lane highway that cost about 5 million euros. German company Solmove plans to install photovoltaic panels that can charge cells beneath a glass surface.

Bavaria in southern Germany has abundant sunshine that produces about a third of the country’s solar power. The Netherlands has claimed ownership of the first solar road, a bike path, since 2014.

Counting the Potential Advantages

The features of SR that its inventors claim include four that concrete provides as well. Providing a flat place to drive, walk or park are capabilities that they have in common. Both surfaces ensure traction and remain hard in high temperatures.

Beyond those, however, the projected benefits of solar panels encased in glass offer significant differences. Embedded processors that give the appearance of intelligence is an innovative aspect, and energy generation is a unique offering.

Among the publicized features of the product are the LED lights that can delineate lane lines or post messages without using paint and the warmth that can melt snow or ice. Having no potholes offers the potential for public acceptance, and the modular construction allows access for repairs when necessary. Claims of return on investment may result from projected energy independence and production of energy for the electric grid.

Storing power or gas conveyances in channels within the panel system improves the aesthetics of the environment, and providing a channel for water allows options to remove it, treat it or store it. Deer can activate alerts to drivers by stepping on the panel surface, potentially eliminating a cause of vehicle crashes. Alerts for emergency warning can provide public service notices.

Examining the Potential Downsides

Forbes published some Quora comments by Mike Barnard, Senior Fellow in Wind at the Energy and Policy Institute regarding the viability of solar roads. The theory that it is possible to overcome costs that are “10 to 40 times more expensive” than traditional surfaces by generating electricity is “pretty flimsy,” Barnard said.

He contends that replacing road paint with LEDs would “degrade the light hitting the solar panels” and put “wiring between the panels and sunlight too,”

Concerned that the electric grid will have to provide power to the panel system, he offered his reasons. In the article “Could Solar Panels Replace Concrete and Asphalt,” he said, “All of the extra lights and gizmos take power, and the sunlight doesn’t shine all the time.”

He expressed concerns about the claim that the solar panels will melt snow and ice. “That tells me that they will have heating coils under every square foot of roadway because after dark the sun won’t be shining. The occasional LEDs won’t be heating much more than the non-heat-conductive glass next to them, and when snow falls in many places, it will dump a nice thick layer that the sun can’t get through.”

He anticipates that clearing snow will require the traditional method of snow removal. Snowplows may not work well while traversing a “bumpy glass surface at 30-50 miles per hour, scraping them off and shattering them.”

Barnard’s view is that it is unnecessary to “add sensors for crashes and traffic flow” when traffic camera analysis, cellphone tower data analysis, and occasionally by stretching counting hoses across the roads” can do the same thing. The multiple goals of the alternative pavement may “replace completely adequate and vastly underutilized existing data streams with expensive infrastructure.”

Facing Challenges to Concrete from Solar Roads

Auburn University’s “Timeline of Concrete” notes the Egyptians’ use of lime and gypsum mortar in building the Pyramids and the application of cementitious materials in the Great Wall of China. Numerous Roman authors wrote about experiments with volcanic ash, sand and lime until they produced material for the Pantheon.

The “art of concrete” disappeared after Rome fell in 400 A.D, but it reappeared in the 18th century. A British mason and bricklayer, Joseph Aspdin, patented a substance that resembled the material in the stone quarries on the Isle of Portland, a name that continues in use. Such an illustrious history of concrete over thousands of years defies challenges by startup entrepreneurs who want to pave highways with 12’ x 12’ glass-encased solar panels.

The web of problems that surround the reinvention of the U.S. highway transportation system makes solar roads seem unlikely anytime soon.