Batteries Will Store and Send Excess Power to Maine Households 950 lithium-ion batteries will not only store excess output from solar and wind power plants, they will also ensure the electric grid is more reliable. Lawmakers want to encourage more projects like this. Tux Turkel, Portland Press Herald | March 9, 2021 | Analysis (TNS) — Sometime in May, two 53-foot-long storage containers, each fitted with roughly 950 lithium-ion batteries, are scheduled to be trucked to an industrial park in Rumford, Maine. The batteries for this $5 million project will be charged at night with cheaper electricity, when demand in New England is low. The next day, when homeowners turn on appliances and business ramps up, the region's grid operators in Massachusetts can remotely dispatch those batteries and send enough power flowing to run 4,000 or so homes for up to two hours.