E-470, a toll road around the Denver area, just added solar over a 17-mile stretch. The project is among the first solar-powered highways in the U.S. and may be the longest stretch in the nation. 

The 696 kilowatt project, which consists of 22 separate arrays, was commissioned at a ceremony on June 27. It was built for E-470 by Martifer Solar USA, the project is owned by Adamas Energy Investments, which has a 20-year power purchase agreement with E-470. As such, E-470 didn’t have to pay anything up front for the project, which is net-metered with Xcel Energy. 

“We have an operations and maintenance agreement with Adamas,” Galesic said. “We’re responsible for system production, but they maintain it not E-470.”

The systems provide about 47 percent of the power used by the highway, according to Nick Galesic. However, the largest array within the larger array, is at its monitoring center. The center has a 106 kilowatt array that offsets 12.4 percent of the center’s electric use, he said. 

The rest of the installations are at the highway’s on and off ramps. “The rest of them are off setting 91 percent of the 21 sites,” Galesic said. Energy use at the private toll road is higher than on most roads. Because it has electronic monitoring stations, cameras and more roughly every quarter mile and at one and off ramps and the data is coordinated at the highway’s control center. 

“We’re always on the cutting edge of solar installations on a national solar scale,” Galesic said. “When highway-side solar projects began to succeed in Europe, we saw the potential in the U.S.”

Martifer found out about the E-470 project after installing three 100-kilowatt systems for the nearby City of Aurora. “The former mayor told me about the project. We responded to a request to meet with E-470 . We beat Johnson Controls and some of the others,” Galesic said. 

Going forward the company is likely to develop other PV highways. “That’s really what we’re going to be targeting throughout the nation. We’re focused on creating channels. Like for schools, solar gardens, then one that focusses on this type of projects. 

While Martifer likely has built the largest PV toll highway it may not be the largest solar highway system. Last year Oregon was moving forward on plans to build a 1.75 MW installation at a rest stop along Interstate 5 and it has plans to build in more solar highway stations.