Troy Howard Middle School recently installed an 11-kilowatt grid-tied solar electric system on the roof of its building on Lincolnville Avenue.

The system consists of 48 Canadian Solar 230-watt photovoltaic panels, two grid-tied inverters, and an online monitoring system so students and teachers will be able to track the array’s production at any time.

Teacher Glen Widmer led the effort to win a grant offered by Efficiency Maine. With this grant, 90 percent of the total system cost will be covered by awarded funds. The system, designed and installed by ReVision Energy of Liberty, will be commissioned Tuesday, April 20.

The 11-kilowatt system covers an area of 845 square feet and is mounted on a roof specifically designated in the original architectural plans for solar panels. This system, based on the roof angle, compass angle and geographic location, will produce roughly 13,600-kilowatt hours of clean, renewable electricity annually and offset roughly 18,000 pounds of carbon dioxide each year.

Grid-tied solar electricity systems require no batteries and instead use the existing electrical grid to store any excess power created on site. Sun hits the PV panels and inverters change the DC power into usable AC electricity. Utility companies in Maine, under net-billing laws, are required to credit any excess production (month-by-month) for up to 12 months.

For more information about Troy Howard Middle School and how it applied for the grant, call 338-3320 and ask for Glen Widmer or visit http://thms.rsu20.org/; for more information regarding solar energy systems, contact ReVision Energy at 589-4171 or visit revisionenergy.com.