A sound barrier along a highway.

A half-mile stretch of Interstate 95 in suburban Boston may soon be home to the country’s first solar panels mounted on highway sound barriers.

The pilot project, which could begin construction as early as this spring, will test an approach to solar installation that supporters say could have a broad reach across the state and country.

“If this is successful, it opens the door to many more sites,” said Mohammed Siddiqui, a partner in Ko-Solar, the company developing the project with the Massachusetts Department of Transportation. “Why don’t we just adapt what we already have and retrofit those existing structures? Most states have sound barriers.”

Ko-Solar began when Siddiqui and entrepreneur Koray Kotan met at a Boston-area networking event and began discussing their mutual interest in green technology. They soon hit upon a vision of building solar projects on and around transportation structures. They began pursuing the idea of using highway noise barriers, attaching a metal grid to the sides of the walls and mounting solar panels at an angle on this framework. 

The company first proposed the idea to the Massachusetts Department of Transportation in 2015. The department was interested. Since 2013, the department has been working on developing solar projects on land around the highways it oversees. Today, eight solar installations on department property generate about 5,300 megawatt-hours of power a year. 

The sound barrier concept opened up even more potential space for such projects. However, as the department began exploring the idea, the state was laying plans to change the structure of its solar incentive program, leaving the financial calculations uncertain. The solar barrier idea was put on hold.

After some delays, the new incentive, the Solar Massachusetts Renewable Target (SMART) program, launched in late 2018. Once it was up and running, planning resumed on the idea of solar sound barriers.

“Government projects come along very slowly,” Siddiqui said. “You just have to be patient.”

The state is in the process of finalizing the letter of intent for the project with the developer. If the plan proceeds as expected, the installation will be mounted on 160 concrete barriers on the southbound side of I-95, one of the busiest commuter roads in the state. The panels will face the roadway, out of view of nearby residents. 

The installation will be owned by third-party solar company Solect, and the transportation department will buy the power generated at a price a few cents per kilowatt-hour lower than the basic utility rate. The array would produce an expected 800 megawatt-hours of power each year — roughly enough to power some 100 homes — creating an estimated savings of $560,000 for the state over a 20-year period. 

To make the financials work, the project will participate in the SMART program, which pays a fixed rate per kilowatt-hour of power produced. The installation qualifies for an extra 6 cents per kilowatt-hour under a provision that gives a boost to projects constructed over an area also used for transportation purposes. In September, the plan also received a $345,000 grant from the state Department of Energy Resources as part of a program that helps state agencies and colleges pursue clean energy projects. 

Together, these state supports are essential to allowing the proposal to proceed, said Don Pettey, program manager for strategic initiatives at the transportation department.

“Without the grant, this would not have had a lot of economic value” to the department, he said. 

As a pilot project, the installation will be closely observed for the first few years it is in operation. The system used to attach the panels will be carefully monitored to ensure they don’t cause damage to the barriers and to confirm they can endure the cold and ice of a Massachusetts winter. Sound levels will be analyzed to make sure the panels don’t compromise the ability of the barriers to block noise. The state will also keep an eye on whether glare off the panels causes problems for drivers on the busy commuter highway.

“This is a bit of a risky project for the developer,” Pettey said. “If we find it isn’t as expected, they’re going to be required to take them down.”

Because it is located along an interstate highway, the project does not need formal approval from the town of Lexington. Nonetheless, Ko-Solar reached out to the town and the residents who live near the project site to explain the plan and ask for their support. Both the project neighbors and the select board embraced the idea.

“They had overwhelming support from the neighbors,” said Mark Sandeen, a member of the select board and the president of solar access nonprofit MassSolar. “We’re very supportive of sustainability initiatives in the town of Lexington.”

While this installation would be the first of its kind in the United States, similar projects have gone up in locations around the world – including Switzerland, Germany, the Netherlands, and Australia – since the 1990s. Assessments of these installations have suggested that they can effectively block sound and generate power, though their cost-effectiveness depends on the specific location, electricity prices, and available solar subsidies. 

The Massachusetts project would act as a testing ground to see if the United States is ready to join this international company. And there is a lot of potential for noise barrier installations: A 2017 study out of Michigan Technological University found the country’s existing noise barriers could bear up to 9 gigawatts of solar capacity.

If the pilot is successful, it could also open the door to more innovative solar projects, Pettey said. The state could look at installing inductive solar charging stations on the back side of solar-equipped noise barriers, for example. 

“This first step will allow us to look at those kinds of things,” Pettey said.

Sarah is a longtime journalist who covers business, technology, sustainability, and the places they all meet. She has covered the workings of small-town government in New Hampshire, the doings of alleged swindlers and con men, and the minutiae of local food systems. Her work has appeared in the Guardian, the Boston Globe, TheAtlantic.com, Slate, and other publications. Based in Gloucester, Sarah covers New England.