BEH's electricity business is carried out by four of its subsidiaries: TPP Maritsa East 2, NPP Kozloduy, Natsionalna elektricheska kompania (NEK) and Elektroenergien sistemen operator (ESO). TPP Maritsa East 2, NPP Kozloduy and NEK all generate electricity through a thermal power plant, a nuclear power plant and hydro-power plants, respectively. NEK buys and sells electricity on both the regulated and free markets. Its principal customers are the four medium and low voltage electricity supply companies in Bulgaria but it also supplies electricity directly to around 90 industrial customers. NEK also exports electricity. ESO is responsible for electricity transmission and runs Bulgaria's electricity grid.
Map of Bulgaria's electricity generation installations and electricity transmission network: