Some of the most energy intensive operations overseen by the Massachusetts Department of Corrections (DOC), including correctional facilities, a wastewater treatment plant, and an MCI industries license plate facility, are now powered by renewable energy in Norfolk and Middlesex counties. Five solar electric system installations spread throughout four towns provide the means to offset the electrical consumption of these state-owned operations. The systems were made possible by funding from the American Recovery and Reinvestment Act and the Massachusetts Leading by Example program.
Solar Design Associates worked with the DOC facilities manager to select four sites on which PV trackers could operate unobstructed year round. Although tracker systems can have a higher initial cost than a fixed tilt system, the four single-axis PV tracker systems installed at Massachusetts DOC sites in Shirley, Concord, and Norfolk provide about 14% more annual energy output than would a 25° fixed-tilt ground mount PV system of the same size. Each row of modules is driven from east to west throughout the day by a central motor. The whole mechanism is controlled by a central box that calculates the position of the sun throughout the year based on the GPS coordinates of the site.