About SONI


SONI (System Operator for Northern Ireland) is the Electricity Transmission System Operator for Northern Ireland. We bring electricity to every part of Northern Ireland and plan ahead for future growth. From our control centre in Belfast, we match supply and demand for power every second of every day by using the transmission system.

The transmission system, or grid, brings power from where it is generated to where it is needed and also powers NIE Networks’ distribution system, which in turn, supplies electricity to homes, farms and businesses.

SONI is independent from NIE Networks. Since 2014, SONI has been responsible for planning for the future of the grid, while NIE Networks is responsible for maintenance, repairs and construction of the grid.

Since 2009, SONI has been part of the EirGrid Group. SONI also operates the all-island wholesale electricity market with EirGrid through the Single Electricity Market Operator (SEMO) which has been in operation since November 2007. SONI is regulated by The Utility Regulator (UR). SEMO is regulated cooperatively by the Commission for Regulation of Utilities Water and Energy (CRU) and UR through the Single Electricity Market Committee (SEM-C).

Learn more about SONI in the videos below.


Since 2006, EirGrid has operated and developed the electricity transmission network in  Ireland. EirGrid is a state-owned company, and pays a dividend to the national income of Ireland each year. EirGrid is independent from ESB. It operates the flow of power on the grid and plans for its future, while ESB networks is responsible for carrying out maintenance, repairs and construction on the grid. The grid moves wholesale power around the country. EirGrid brings energy from generation stations to heavy industry and high-tech users. It also supplies the distribution network operated by ESB Networks that powers every electricity customer in the country.


EirGrid Website


SEMO is the Single Electricity Market Operator for the island of Ireland. This organisation runs the wholesale market for electricity. This allows companies to make bids to buy or sell electricity in bulk. A well-run electricity market is essential for all those who need this energy. It provides fair and independent pricing for those who generate electricity. It also permits competition in the sale of power, which benefits every electricity user.

SEMO Website

EirGrid Group

Our task is to deliver a safe, secure and reliable supply of electricity – now, and in the future. The EirGrid Group achieves this goal through a family of organisations - SONI, EirGrid and SEMO.