From their perch overlooking a busy stretch of Interstate 95 in New Haven, the 1,900 solar panels that sit atop the city’s old landfill are a prominent display of a growing trend in Connecticut.

The solar array, built by Greenskies Clean Energy, is one of at least 29 large arrays that have been built or approved to be built on top of closed, capped landfills — a number that will likely increase in the coming years, according to state officials and developers.

That number is from the Department of Energy and Environmental Protection, which must approve permits to construct projects on top of capped landfills. Those caps are designed to prevent the spread of leachate and other pollutants into the environment. The agency is currently reviewing permit applications at four other capped landfills, according to a spokesman.

Ryan Linares is the vice president of land acquisition at Greenskies, a solar energy company that opened its first two solar landfills in 2016 in Meriden and North Haven. Since then, its portfolio has grown to include landfills in Fairfield, West Haven and East Haven.

Its newest facility, the one in New Haven, opened in July.

While many of the state’s 294 closed landfills are candidates for solar fields, not all are.

Linares said that his company typically looks for landfills with a flat “plateau” of about 5 acres, which he said is large enough for a 1 megawatt facility. Proximity to existing electrical infrastructure is also essential to allow the solar array to connect to the local power grid.

One of the benefits that solar developers see in landfills is that they are usually town-owned and have limited opportunities to be sold or put to other productive uses. Companies can also make use of state incentives for the redevelopment of brownfield sites. 

“It’s a very good argument to say that this is the highest and best use, and we typically don’t see much pushback on that,” Linares said.  

Because landfills are contaminated areas, penetration of the cap, or the material sealing the landfill, is usually not permitted. It’s for that reason that large, shady trees are often prevented from growing over the cap — allowing plenty of access for sunlight. 

The number of solar fields on landfills has increased in the past decade. Since 2023, six projects have been approved by the Connecticut Siting Council, which has jurisdiction over projects with a capacity over 1 megawatt. (Smaller projects, such as those developed by Greenskies, are subject to local jurisdictions).

Linares said that Greenskies’ own portfolio of landfill arrays will likely double in size by the end of next year as it wraps up projects that are under active development.

“The programs in the state of Connecticut [are] really incentivizing development on brownfield or landfill properties, as opposed to other vacant pieces of property that aren’t brownfields or landfills,” he said.