Close-up

Tecta America New England, North Billerica, Mass., recently installed a roof-mounted photovoltaic (PV) system on the 30,000-square-foot roof of Pearson Ventures' office building in Billerica, Mass.

Tecta America decided to install a PV system because local incentives and the federal investment tax credit made it more economical, reportedly providing a 12 to 15 percent internal rate of return during a 10-year period and producing 100 percent of the facility's electricity requirements.

The original roof system consisted of a 22-gauge Type B steel deck, 2 inches of polyisocyanurate insulation and a ballasted EPDM roof system.

"In preparation for the PV system, the ballast was removed, seams were 'stripped in' and all penetrations were reflashed," says Brett Chapman, president of Tecta America New England. "Upon completion, ballast was re-installed at areas not covered by the PV modules."

The company then installed the PV system, which features Schüco MPE 220-watt modules and a Schüco ezFlatRoof 2.0 Mounting System with an energy output of 143 kilowatt (kW) peak units. A Satcon® PowerGate Plus 135-kW solar PV inverter converts all the DC power produced by the solar modules into usable AC power. A revenue-grade, Web-based monitoring system was installed to provide data collection, real-time viewing from anywhere and direct reporting to Massachusetts Production Tracking System to allow for trading of the solar renewable energy credits produced.

"We have a data monitoring system in place to show how much energy is being produced in real time so we accurately can measure our return on investment," Chapman says.

The PV system is estimated to produce between 3.575 million and 4.6475 million kilowatt-hours during the next 25 years. Reduction of carbon dioxide production is slated to be 5.005 million to 6.435 million pounds. Additionally, the roof is accessible, allowing potential Tecta America customers to view the PV system.

All safety and PV equipment was hoisted to the roof using Tecta America's 40-ton crane, and the appropriate safety precautions were taken.

"Before the project began, Garlock's RailGuard System was installed at the ladder access and loading area," Chapman says. "The balance of the perimeter was secured by Garlock's perimeter warning system of stanchions and flags. For work outside the warning lines, the AES Raptor Trex was used for tie-offs."

"The most challenging aspect of the project was handling all the required paperwork for a myriad of government incentive programs, permits and utility connections," Chapman continues.

But balancing the project's various aspects made it rewarding.

"We provided a turnkey solution for the owner, handling all the engineering, permitting, interconnection agreements, procurement and construction," Chapman says. "The owner received our unique warranty that covers the roof and solar power plant."

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