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."