Electricity deregulation is giving a boost to clean energy in Pennsylvania — about a third of state residents who have chosen a new electricity supplier since the market opened have switched to renewable energy, according to officials at Conectiv Energy, which operates windmills in the state. Demand for wind energy has exceeded the company’s supply, pushing Conectiv to construct more wind turbines. Green Mountain Energy recently broke ground on a $10 million wind farm in the state, with eight turbines that will produce enough electricity to power 2,500 homes. Last month, Conectiv teamed up with the Clean Air Council to offer photovoltaic panels free to Philadelphia-area schools, with the stipulation that the schools would buy from Conectiv any additional power needed beyond what the solar panels provide. This effort is helping to advance a federal program that aims to install solar systems on one million rooftops in the U.S.