BIDDEFORD — It’s been nearly 100 years since the Saco River powered the textile mills that sit on its banks. Now a different form of renewable energy will power the sprawling brick buildings at the center of the city’s revitalization.

The Pepperell Mill Campus soon will become home to the largest rooftop solar installation in Maine, according to installer ReVision, when nearly 1,200 solar panels are installed on the roofs of three buildings that house 100 apartments.

The largest municipally operated solar array in the state is in Madison, where a 26,000-panel array generates enough electricity to power 700 homes.

Doug Sanford, the developer and owner of 1 million square feet of mill buildings, said he has planned to find ways to use renewable energy since buying the first building well over a decade ago.

“The cost was always an issue,” he said.

But the cost of installing solar panels has dropped to the point where it is feasible to install the array, which is predicted to produce enough energy to more than cover the needs of the campus’s 100 residential units.

Sanford said he will invest up to $1 million in the project, but the final cost has not been determined. The project will pay for itself within 10 years. Sanford plans to leverage federal tax credits available for solar projects.

The 1,192-panel solar array spread over 1.5 acres of rooftop will produce 437,320 kilowatt hours of energy annually, more than enough electricity to meet the needs of the campus’s 100 residential units. The remaining electricity generated by the solar array will be allotted to the 51 new apartments currently under construction and due to come online next spring.

Scott Joslin, general manager of Pepperell Mill Campus in Biddeford, walks along the roof of one of the mill buildings where a large solar panel array is being planned on Friday, July 27, 2018. Staff photo by Shawn Patrick Ouellette

The array will be connected to the power grid and will run through a Central Maine Power meter, campus officials said.

The array will result in annual carbon offsets of approximately 460,498 pounds per year, the equivalent of the annual greenhouse gas emissions from 40 passenger cars driven for one year or 500 barrels of oil.

Sanford said if the project works out as predicted, he plans to expand the system over more of the 12 acres of flat roofs at the complex. He also would like to partner with neighboring mill owners and create a renewable energy district.

Sanford expects the solar array to be installed before Christmas and come online by next spring.

A crowd gathered for a press conference at the Pepperell Mill Campus in Biddeford, where company leaders announced plans to install the largest privately held solar energy project in Maine on Friday, July 27, 2018. Staff photo by Shawn Patrick Ouellette

U.S. Sen. Angus King visited the Pepperell Mill Campus Friday to announce the partnership between the company and ReVision Energy, which will install the panels. King, who toured the campus with Sanford, praised the solar project and Sanford’s progress in transforming the former textile mills into a “city within a city.”

King, an independent, called solar power the “great revolution in American energy” and said the drop in cost in recent years allows people like Sanford to use renewable energy. Last week, King visited with a farmer in Mapleton who installed a solar array in one of his fields.

“This is happening all over Maine,” King said. “We have an amazing resource.”

“That’s what’s going to change America and it will change it for the better,” he added.

Phil Coupe, cofounder of ReVision Energy, said the Pepperell Mill Campus solar array is a “unique project in the heart of Biddeford’s economic and cultural revival.”

State Rep. Marty Grohman, an independent who represents Biddeford and is running for Congress, said the project will be an anchor in downtown Biddeford.

“I deeply believe that expanding solar is a critical part of Maine’s economic and energy future, so I’m glad that it’s also a growing part of our present,” he said.

The project was also praised by Mayor Alan Casavant, who called it “an exciting time for Biddeford.”

City leaders, including Casavant, consider Sanford a pioneer for leading investment in the mill district and have said the Pepperell Mill Campus is drawing attention to the city’s revitalization, bringing new businesses and residents to the community and expanding Biddeford’s tax base.

Sanford and his company have invested $40 million to $50 million in the mills since 2004. The 16-acre campus is more than 65 percent complete and plans are in the works for more housing, a hotel and the expansion of light industrial space.

The campus includes more than 115 businesses and 100 residential apartments. The apartments are a mix of studio, one-bedroom, two-bedroom and luxury loft units. Rent includes all utilities.

During a tour of the campus before a news conference announcing the solar project, Sanford showed King the mix of businesses on the campus, including a brewery, hiking equipment manufacturer and a glass blowing studio.

King, who last visited the mill five years ago, said he was amazed by the “phenomenal” transformation of the complex, which sits in the middle of downtown Biddeford.

“Biddeford is the most dynamic community in Maine right now,” he said.

Gillian Graham can be contacted at 791-6315 or at:

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Twitter: @grahamgillian