There has been a lot of talk about solar roads in the past couple years. They sound like a great idea, and there is certainly a lot of support for them, but we're still quite a ways away from seeing them take over our road system.

One solar road project that's been getting attention lately is the SolaRoad project in the Netherlands. The company installed 230 feet of solar road panels on a bike path near Amsterdam last year, and it recently found that the path is creating more energy than expected. The road has produced 3,000 kilowatt-hours of electricity, which is enough to power a small house for a year. The path was created by placing three-eighths of an inch of durable, textured glass over solar cells.

The most famous project of this kind in the United States is from the Solar Roadways company. Scott Brusaw and his wife Julie started tinkering with the concept in the mid-2000s, and they received their first grant to fund the project in 2009. They received $100,000 from the Department of Transportation (DOT) for research, and they built their first 12' x 12' array in 2010. The company has since received a $50,000 award from GE, another $750,000 grant from the DOT, and raised over $2 million with an Indiegogo crowdfunding campaign.

The company is now working with panels that are 4' x 4' hexagons and some half-hexagons. The panels are covered by a half-inch thick tempered glass surface. Currently, there is a parking lot with 108 prototype panels in Sagle, Idaho. Tests at a university lab have shown the raised hexagonal solar panels designed for highways are able to safely stop a vehicle going 80 mph on a wet surface. Since the company is still in the testing phases, the long-term durability of the panels and the cost of covering an entire highway are unknown. However, many have said that the cost of covering the highway system in panels would be far too high, since installing panels currently takes much more labor than pouring asphalt.

“We have no idea what sort of real costs would be associated with [solar roads],” Doug Hecox, a public affairs specialist for the Department of Transportation, told ATTN:. He said there needs to be a lot more data available concerning cost, efficiency, and durability before anything can happen. “It's very preliminary right now,” he said.

The process for installing the panels may be streamlined in the future, which could make it possible for the highway system to be outfitted with panels, but it's probably going to be a while. The panels have to be correctly networked so the entire system can communicate, which could provide benefits like knowing when one panel needs to be replaced. Replacing the panels could actually be quite easy, since the maintenance worker would just have to pick up something that doesn't weigh much more than 100 pounds and put in a new one, which could conceivably take as little as half an hour.

“My guess is, initially, it's going to cost significantly more than asphalt," Hecox said. "Right now, with every state in the country and every territory unable to pave the basic roads and bridges they already have, expecting them to pay more for something like this is a little hard to believe, but … maybe in a few years the world will be different.” He said he hopes it can be done at a reasonable price and that cities and states will invest more in infrastructure, but it's hard to say if that will actually happen.​

Since the technology is still in its infancy, it is better to test it at a smaller scale. Solar Roadways notes on its website that it plans to start with building sidewalks, driveways, and parking lots before it ever actually builds a working solar road. Observing how the panels work in parking lots and sidewalks will help educate the company on how feasible it is to build roads.