Charlestown Patriot Bridge: “Boston Sand & Gravel completes largest Commonwealth solar energy project ” December 18, 2008. Designed and installed by Nexamp, Inc. of North Andover, a turnkey clean energy solutions company, and financed with help from the state’s Commonwealth Solar initiative, the more than 550- panel PV system covers 22,000 square feet and will produce 75 percent (120,000 KWH) of the power used by the maintenance facility each year. Link to Article.