The company of the Electricity System Operator - ESO EAD has been established on January 04, 2007 as a subsidiary of the national electrical company - Natsionalna Elektricheska Kompania - NEK EAD.
The Electricity System Operator performs the general operational planning, coordination and control of the electrical power system of the Republic of Bulgaria, as well as its common operation with the electrical power systems of other countries. The Electricity System Operator provides for the operation, maintenance and reliable functioning of the power transmission network, keeps and maintains the auxiliary networks, carries out maintenance activities and services in the field of the energy sector. The company implements transit of electricity. It is also responsible for the electricity market.