Description When it's dark in Dayton, DPL turns on the lights. The holding company's main subsidiary, regulated utility Dayton Power and Light (DP&L), which was established in 1911, brightens the night for more than 500,000 electricity customers in 24 counties in west central Ohio. Nonregulated subsidiary DPL Energy operates DPL's 10 power plants, which produce more than 3,800 MW of primarily coal-fired generating capacity. It also sells power to energy marketing affiliate DPL Energy Resources to meet the electric requirements of its retail customers. Other activities include street lighting and financial support services. In 2011 DPL was acquired by AES in a $4.7 billion transaction.