“In theory, solar PV roadways sound great. The issue is cost.” says Mark Jacobson, an engineering professor at Stanford University who has promoted a plan for powering the U.S. solely with renewable energy. (Read about his blueprint for a carbon-free America.)“Aside from road dust, particularly black tire dust and diesel exhaust, which will quickly cover a portion of each panel, the continuous traffic covering panels will reduce their solar output,” says Jacobson, adding they’ll likely suffer more wear and tear and need more repairs than other solar panels.He also says that while they don’t require land acquisition costs, as do solar power plants, their panels cannot be rotated for optimal solar exposure. He expects a solar road won’t be able to compete on cost, but “I’m hopeful it will.”“Installing photovoltaics in roads seems like a daft idea at first, “says a report last month by IDTechEx, an independent research and consulting firm. “A closer look reveals that most of the problems are easily overcome and even at poor efficiency, that local electricity has viable uses.”Despite high costs, company chairman Peter Harrop says solar roads might work in places that are putting down roads for the first time. “They need early (technology) adopters like China that want to leapfrog in development.”In contrast, “I can’t see solar roads in London,” he says, noting the city often digs up its roads for underground repairs.
So far, the Netherlands’ solar path is popular. In its first year, 300,000 bikes and mopeds rode the initial 70-meter (230-foot) stretch connecting two Amsterdam suburbs. Officials say the SolaRoad produced more energy last year than expected—enough to power three households. It’s made of crystalline silicon solar cells, encased in concrete and covered with a translucent layer of tempered glass.In the U.S., Solar Roadways has received more than $1.5 million from the Department of Transportation over the last six years to develop and test its hexagonal-shaped panels.“One of the shortcomings Solar Roadways has yet to resolve is the manufacturing process,” two DOT officials wrote in a December post, noting the solar cells are handmade and thus “very costly” to produce. Julie Bursaw says the company’s most recent prototype is less costly to produce, 25 percent more efficident, and easier to install.The DOT officials, Michael Trentacoste and Robert C. Johns, say the agency has received “a lot of positive feedback” about the project; the company’s promotional video has 21 million views on YouTube. Because the panels can melt snow or keep water from freezing, even with high costs, they say the innovation “could still be useful in smaller areas such as parking lots, sidewalks, driveways, and bike lanes.”The story is part of a special series that explores energy issues. For more, visit The Great Energy Challenge.