SALEM — Over the next few months, workers will be installing solar panels on a Salem apartment complex that will have one of the largest photovoltaic arrays in the state.

At the Princeton Crossing apartments, across from Salem Hospital, nearly 2,000 roof-mounted solar panels are expected to generate enough electricity to power all of the common areas in the complex of 17 buildings, including laundry rooms, lounges, outdoor lighting and pumps for the heating system.

"In this economic environment, it's one of the few fun and exciting things happening ," said Kurt Shillington, operations manager at Princeton Properties, which manages the Salem complex.

The new solar array has a 347-kilowatt capacity — "enough to power 80 to 100 small homes on an annual basis, depending on how much electricity they use," said Shillington.

A spokeswoman for the Massachusetts Renewable Energy Trust said it will be one of the biggest solar projects in the state.

Solar panels, measuring roughly 21âÑ2-by-5 feet, are being mounted on the south-facing roofs. Installation will take about two months to complete.

The project was made possible, Shillington said, by a combination of state and federal financial incentives, including grants (some from federal stimulus funds), tax benefits and an incentive to go green with affordable housing, for which Princeton Crossing qualified because 25 percent of its apartments are affordable.

The project will cost $1.95 million, but with the various incentives and rebates — and subsequent energy savings — the company expects to recoup its costs within two years, according to Sarah Greenough, vice president of Princeton Properties.

"(That's) kind of unheard of with solar," she said.

How it works

Electricity generated from the solar panels is fed into the power grid, and Princeton Properties draws from that pool of electricity.

"Their net electricity usage is lowered by the solar photovoltaic system," said Emily Dahl, a spokeswoman for the Massachusetts Renewable Energy Trust, which administers the Commonwealth Solar Rebate Program. The rebate program, launched by Gov. Deval Patrick in January 2008, has awarded more than 1,000 rebates for solar photovoltaic projects like Princeton Crossing, according to Dahl.

The amount of kilowatts generated by the solar array will be subtracted from their total electricity usage, said Dahl.

Shillington estimates the new system will produce around $70,000 worth of electricity annually, and the usage for the common areas is about $65,000. He said the system will also produce around $12,000 in Renewable Energy Credits.

The life expectancy of the solar array is 25 to 30 years, Shillington said, so it's a way to "insulate yourselves from the volatility of energy costs" over the next three decades — and possibly save $2 million.

Dahl said there are other ways to put the energy savings into perspective.

"The Princeton Crossing array will offset the carbon dioxide equivalent of planting approximately 115 acres of trees per year," she said. Also, "the electricity it produces is the equivalent of taking approximately 48 cars off the road each year."

Going green could also benefit residents of the complex financially.

"Our operating costs have a trickle-down effect to rental rates," Shillington noted.

Market-rate units at Princeton Crossing, which was built in 1971, cost between $960 and $1,020 for one bedroom and between $1,195 and $1,270 for two bedrooms. The affordable rates are $771 for one bedroom and $913 for two bedrooms, according to Greenough.

"We're happy to get involved with this," said Greenough. "We try to be as forward-thinking as we can with the wallet size we have."

The Salem site is the first solar project for Princeton Properties, which is based in Lowell and manages 38 apartment communities in Massachusetts, New Hampshire, Maine and Georgia. It now plans to install solar arrays at two other sites, in Chelmsford and Billerica,

Shillington said the solar arrays and components for the Salem site were all made in Massachusetts.

He believes a growing thirst for energy and the rising cost of fossil fuels will inspire more of these projects in the future.

"This is certainly a trend that's going to continue around the country," said Shillington. "We're well behind Europe."

Staff writer Amanda McGregor can be reached at amcgregor@salemnews.com.