First things first. FirstEnergy Solutions (formerly Allegheny Energy Supply) serves more than one million residential, commercial and industrial customers in the Northeast, Midwest and Mid-Atlantic regions. It operates 35 plants with 23,000 MW of generating capacity and supplies electricity to customers in Illinois, Maryland, Michigan, New Jersey, Ohio and Pennsylvania. It also manages the energy and procurement needs for more than 120,000 business clients. Allegheny Energy Supply, the former power production subsidiary of utility holding company Allegheny Energy, which was acquired by FirstEnergy in 2011, was merged into FirstEnergy Solutions.