New London ― Contractors later this year are expected to install 612 solar panels onto the roof of the city’s high school, an addition expected to cut monthly electric bills at the Chester Street building by about $6,000.

The City Council on Monday unanimously approved a power and services agreement with Greenskies Clean Energy LLC for the installation, operation and maintenance of the solar photo-voltaic system.

The installation work will be done at no cost to the city, though its share of a previously completed high school roof-reinforcement project came to roughly $16,000, Director of Public Works Brian Sear said on Thursday.

That $80,000 project ― 80% of which is reimbursable by the state ― was needed to ensure the roof was sturdy enough to bear the weight of the 40,000 contiguous square-feet of solar panels, Sear said.

Sear said the high school solar project topic was proposed in 2019 and later approved by the city’s School Building & Maintenance Committee.

The city worked with the Commercial Solar Works consulting firm on the solar project which is pegged to deliver an estimated 373,000 kilowatt hours of electricity to the school for the first year of operations, or just more than 31,000 kilowatt hours a month.

Estimated production dips over the course of the 20-year contract as panels age and become dirty. By year 20, the panels are expected to deliver 337,900 kilowatt hours of power.

Sear said the school – the only beneficiary of the panel power – uses approximately 120,000 kilowatt hours of electricity each month. Its Eversource bill, which includes a 25-cent-an-hour generation and delivery charge, comes to about $30,000 a month.

“The panels will reduce that bill by around $6,000 each month,” Sear said.

Miguel Gautier, the school district’s director of facilities, said the panel installation news comes at a fortuitous time.

“For the first time, we’ve added air conditioning to the school and I’m very aware of how expensive it’s going to be to cool the entire building,” he said. “So, if we can cut our electric bill, costs, especially with Eversource costs on the rise, that’s a huge advantage for us.”

The high school project will represent only the second instance of solar panels being added onto a New London municipal building. Roof panels were installed on the Winthrop Stem Elementary Magnet School on Grove Street several years ago.

“It’s the age of some of our buildings and their roofs that prevent us from adding onto more structures,” Sear said. “And those roofs have to be able to properly angle the sunlight.”

The high school job will be followed by a much larger solar installation project on a four-acre section of Bates Woods. That project, tentatively set to begin in the fall, calls for 3,000 ground-mounted panels to be planted in a southern portion of the park atop a capped landfill.

“That will generate 1,741 megawatts a year into the grid,” Sear said.

j.penney@theday.com