Solar developers are finding interesting places to put their panels: landfills, parking garages, warehouses, shopping malls.

Now, the Massachusetts Department of Transportation is adding a particularly unusual spot to the list: highway sound barriers.

On Monday, MassDOT announced it had signed a letter of intent to create the first such solar “photovoltaic noise barrier,” or PVNB, by mounting solar panels on an existing sound barrier along Route 128 in Lexington in the coming months. The 638-kilowatt project could provide enough power for up to 120 homes. Solect Energy will finance, install, and maintain the 3,000-foot-long project, while Ko-Solar, a Natick startup owned by Koray Kotan, is developing it. Kotan said Ko-Solar is in talks with transportation agencies in several states but the MassDOT project will be the first of its kind in the United States.

A MassDOT spokeswoman said the agency expects to receive a financial benefit of about $23,000 a year over the course of a 25-year lease period, from a combination of lease payments and electric utility savings from the credits the agency will receive for providing the power for the area’s electric grid. The state Department of Energy Resources awarded a $345,000 grant to help subsidize this pilot project.

MassDOT officials considered about two dozen potential sites, and selected the Lexington spot in part because of the sun exposure that it gets. The agency said it only moved forward after receiving unanimous consent from abutting property owners. MassDOT will monitor sound levels to ensure there is no increase in highway noise as a result.

Ko-Solar first approached state highway departments about the concept in 2015, around the same time that MassDOT launched a much bigger solar rollout for highway rights of way with Framingham-based Ameresco.

State transportation undersecretary Scott Bosworth said the agency will look at possibly expanding the solar concept to other concrete sound barriers, if the financial results make sense and noise reduction is not impeded. Bosworth said he remains hopeful that Ko-Solar’s proposal could become a national model.

“We want people to see we’re trying new technologies in order to reduce our carbon footprint,” Bosworth said. “We think it’s a really neat opportunity and expect it’s going to turn into not only an expansion in Massachusetts but countrywide.”

Patrick Canning, vice president of engineering at Boston-based solar company Nexamp, said solar developers in Massachusetts are increasingly looking for opportunities to build smaller projects in more heavily developed areas, as opposed to larger projects in rural locations. That’s in part due to the complexities of interconnecting larger arrays to the region’s power grid, and also due to the state’s solar incentive program, known as SMART, which encourages infill projects.

“This is taking that concept as far as you can, in really distributing it into urban environments,” Canning said. “I’ll be watching this pilot to see how the costs work out.”

Jon Chesto can be reached at jon.chesto@globe.com. Follow him on Twitter @jonchesto.

Work at Boston Globe Media