Windham’s new solar project utilizes local rock to bring local solar energy to its community.

The Town of Windham, Maine, celebrated their new 504-kilowatt array with a socially-distanced, masked-up ribbon cutting last month. The array, comprised of 1,344 photovoltaic panels, will produce over 684,000 kilowatt-hours of clean, solar electricity annually for its residents.

The Windham solar array is another example of a solar project sited and developed on land with limited productive use, granting new value to unserviceable land. Building on a capped landfill was a particularly appealing part of this clean energy project, according to the Town Sustainability Coordinator, Gretchen Anderson.

“The Town of Windham was excited to pursue this project to boost energy efficiency and realize significant savings in electricity costs over time,” said Gretchen Anderson. “By utilizing the closed landfill for the solar array, the project creates the opportunity to give otherwise unusable land a new life by converting it into a site to generate solar energy and revenue. Additionally, our residential energy efficiency campaign will help Windham residents reduce energy consumption and save money.”

While a number of local towns and cities have installed solar on their capped landfills, Windham is one of the first to use local rocks as ballast. Because the ground can’t be penetrated on capped landfills, ground-mounted solar arrays need to be held down with heavy ballast, usually made of concrete. For the Town of Windham, the ReVision engineering and design teams opted to use crushed bedrock from two local quarries: one right down the street and one in the neighboring town of Gorham.

The bedrock harvested from the quarries is readily available up and down the East Coast, having been formed literal ages ago in the Paleozoic Era, when tectonic plates colliding created the current topography of Eastern North America.

Concrete normally used for ballast is carbon-intensive, so by using local bedrock we could increase the town’s carbon savings. While there were some challenges in using loose stone instead of concrete, ReVision’s Project Manager, Josh Baston, believes the advantages greatly outweigh these challenges. Josh has a degree in geology, so this project was particularly exciting for him.

“Outside of installation advantages, the environmental advantages are huge. We used an abundant local resource and one that does not have the huge carbon footprint of concrete production. At the end of the array life we don’t have a bunch of concrete that would need to be landfilled, but just stone which can be re-purposed!”

—Josh Baston, Project Manager

Thanks to this innovative technique, the Town of Windham will be saving over 671,000 pounds of carbon every year. This is equivalent to taking 105 passenger cars off the road, or planting 8,000 tree seedlings. Read the local news coverage of the ribbon cutting in The Windham Eagle.