Experts believe that the PJM Interconnection system, which encompasses all or parts of Delaware, Illinois, Indiana, Kentucky, Maryland, Michigan, New Jersey, North Carolina, Ohio, Pennsylvania, Tennessee, Virginia, West Virginia and the District of Columbia, can handle up to 30 percent of its energy from wind and solar without "any significant reliability issues," assuming transmission upgrades and additional regulation reserves — and at the same time reducing costs and reliance on its costlier conventional generation fleet.