MADISON — The state’s largest solar farm could be fully operational this week.

The solar energy project in the Madison Business Gateway is more than twice the size of any other in Maine and was constructed by Ohio-based IGS Solar over the summer and fall. It was originally expected to be up and running by Thanksgiving, but the permitting process took longer than expected and construction ran behind.

The farm will produce nearly 5 megawatts of electricity and Madison Electric Works will purchase all of it, said utility Superintendent Calvin Ames. He expects the project to be online by the end of this week or very early in the new year.

“Everything is getting tested and hooked up now, and it should be producing all kinds of electricity on sunny days,” he said.

ISG was awarded the contract to build and own the solar farm last spring. Madison Electric signed a 26-year agreement to purchase the electricity produced at a fixed rate of 7.99 cents per kilowatt. After six years, the utility will have the right to purchase the farm at an estimated cost of about $6 million, Ames said.

The farm will supply power to about 20 percent of the district’s customers overall, but Ames said on a sunny day it will meet the needs of 100 percent of the utility’s customers – about 3,000 homes and small businesses, excluding Backyard Farms.

The farm consists of about 26,000 solar panels and occupies nearly 22 acres of land in the Madison Business Gateway. The project originally was planned to produce about 3.4 megawatts, but the capacity grew to what is essentially 5 megawatts. ISG paid the full project cost of about $10 million.

Madison Electric, a publicly owned utility, put the project out to bid in November 2015. Ames said the construction went smoothly, using mostly local workers, and there were “no real bumps in the road.”

The Madison solar farm in Somerset County is one of a handful of such projects being implemented across Maine. The Oakland Planning Board recently approved a site application from Colby College in Waterville to build a 1.9-megawatt installation with 5,505 solar panels on Washington Street, with the work beginning in January. Bowdoin College has a 1.2-megawatt solar power complex in Brunswick. And a Yarmouth company continues to move ahead with plans to build a 50-megawatt solar farm at the Sanford municipal airport. The Sanford City Council approved the lease back in May.

Ames said the Madison project should create a 2 percent savings, but because the rate is fixed for the 26-year agreement, he estimated the savings will grow as the year pass. He called the farm “risk-free” because Madison Electric will only buy the kilowatts produced. If the savings aren’t what the utility expects, it doesn’t have to buy the solar farm.

“The beauty of the thing is it’s not necessarily cheap today, but the price is fixed,” he said. “We don’t have to buy it if we don’t want to.”

If Madison Electric does not buy the farm after the 26-year agreement is up, ISG will either give it the farm or take it away.

“After 26 years, it will basically be free,” he said.

This story was updated at 11:48 a.m. on Thursday, December 29, 2016 to correct the name of the Ohio company that built the Madison solar farm.