The Single Electricity Market (SEM) is the wholesale electricity market for the island of Ireland where suppliers and generators trade electricity.

The SEM is designed to provide for the least cost source of electricity generation to meet customer demand at any one time across the island, while also maximising long-term sustainability and reliability.


It is overseen by the regulatory authorities in Ireland (CRU) and Northern Ireland (UR) through the SEM Committee (SEMC). This committee also has one independent member.

Proceed to the SEM Committee website for more information about the governance, structure and proceedings of the SEM Committee

The SEM is operated by the Single Electricity Market Operator (SEMO) – which is a joint venture between the transmission system operators in both jurisdictions – EirGrid and System Operator Northern Ireland (Soni).

Market Rules

Rules governing the SEM and procedures for registering as a market participant (supplier, generator, DSU, etc.) can be found along with more detailed information at