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Solar farm slow to generate power for Plymouth schools

A large solar farm in Plympton that was supposed to start producing power for the Plymouth public schools this summer has yet to yield the results school officials had hoped for.

The 5.7-megawatt solar farm was scheduled to go live at the end of July, but wasn’t able to connect fully to the grid because of work NStar has been doing.

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The project took a big step forward last Wednesday, when it started producing electricity, said NStar spokesman Michael Durand. He said the farm will be fully operational by mid-October.

But the loss of more than two months of solar power could mean the Plymouth Public Schools won’t realize expected savings of $35,000 to $40,000 during that period, according to Gary L. Costin, business administrator for the school system.

The postponed opening of the Plympton facility is “something we’re not happy about,” said Costin, “but delays do happen.

“Any time we have to spend money that we have not budgeted is a concern,” said Costin in a telephone interview. “Essentially, there will be less savings than we calculated.”

A ribbon-cutting ceremony for the solar farm is scheduled for Oct. 29, according to Costin, who added: “We’re just happy that it’s going to be up and running before the end of October.”

‘Any time we have to spend money that we have not budgeted is a concern. Essentially, there will be less savings than we calculated.’

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Located off Brook Street, the solar farm covers more than 23 acres on land leased from Plympton Sand & Gravel. The array was installed by Borrego Solar Systems Inc., a San Diego-based company with offices in Lowell. Plymouth was one of the first school districts in Massachusetts to agree to buy electricity through the company.

Under the terms of the deal, power generated by the array will count as energy credits for the Plymouth schools. In the parlance of renewable energy, this is known as a “net-metering agreement.”

Plymouth school officials had estimated that the farm would result in $400,000 in savings in its first year of operation. (The school district spent about $1.6 million for electricity in fiscal 2013, which ended June 30.)

But NStar must first finish upgrading a nearby substation before the farm can be fully connected to the grid. Durand said that NStar had originally hoped those upgrades could be made before the summer, but that wasn’t possible during the hot weather. A substation would have to be taken out of service temporarily while it was connected to the solar farm, Durand said, but NStar needs every substation up and running during the summer in order to meet the higher demand for electricity.

Durand said NStar and Borrego recently reached an agreement to connect “partially” first, so the solar farm will be able to generate up to 1.5 megawatts of electricity. According the Durand, the farm reached that level late Wednesday.

Then, once the rest of the work to the nearby substation is complete, the solar farm will be able to connect fully and reach its maximum output. The energy it generates will flow into the grid, which will in turn produce credits that will reduce the utility bills for Plymouth schools.

Meanwhile, Plymouth schools are taking the estimated financial loss in stride, and have not made any plans to cut spending to make up for the loss of savings that had been budgeted. For now, the schools will assess the savings that the solar farm will generate once it’s running at full capacity.

“We intend to monitor our total utility budget and postpone any additional energy-saving measures that we had budgeted until we have a firm forecast on our utility costs,” said Costin, in an e-mail. “Hopefully, we will have a mild winter, which will negate the delay in the activation of the solar farm and allow us to complete additional energy-saving measures.”

Emily Sweeney can be reached at emily.sweeney@globe.com. Follow her on Twitter @emilysweeney.
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