Wholesale Trading Arrangements

All-island SEM

Since 1st November 2007 there has been a single wholesale electricity market in place across the island of Ireland, known as the Single Electricity Market (SEM). The SEM was put in place by the two regulators north and south (Utility Regulator in Northern Ireland and CER in the Republic), working in cooperation with the two Governments and the electricity industry.

The SEM allows for generators to sell their electricity into a "central pool" and for electricity suppliers to purchase their electricity out of this pool. The SEM is designed to ensure that the most efficient electricity plants are run first (in the absence of any network contraints).

The SEM is regulated by the SEM Committee, which is a cross-jurisdictional body made up of the two regulatory authorities (CER and Utility Regulator) and an independent member.

For a high-level overview of SEM, how it is governed and how it operates, please see the CER factsheet on SEM which is available here.

Full details of the design of SEM, the SEM Committee and its regulatory consultations/decisions can be found on the Regulators' website for the SEM - www.allislandproject.org

Market Operator

The SEM is operator by SEMO - Single Electricity Market Operator. SEMO is a joint venture between EirGrid, the TSO for Ireland and SONI, the TSO for Northern Ireland. SEMO publishes details of market operation on its website, including information on the half hourly wholesale electricity prices in the market.

To view the SEMO website, please click on either of the links below:

www.sem-o.com

www.allislandmarket.com

Trading Arrangements Pre-SEM

Before the implementation of the SEM, a different market regime applied in Ireland. The direction on the Transitional Electricity Trading Arrangements, below, sets out the basic features of the previous electricity trading arrangements, which were replaced by SEM on 1st November 2007. These arrangements were based on a bilateral contract market supported by a top up and spill energy imbalance regime.

Click here to view the Minister’s Policy Direction on the (pre-SEM) Transitional Wholesale Electricity Trading Arrangements:

Policy Direction - Trading in Electricity dpetrade.pdf (0 MB, Adobe PDF)

Consultation on East-West Interconnection Access Rules: EirGrid are consulting on the Access Rules that shall apply to the East West Interconnector. These rules will be subject to regulatory approval.
Wholesale Prices: The SEM consists of a gross mandatory pool market, into which all electricity generated on - or imported onto - the island of Ireland must be sold, and from which all wholesale electricity must be purchased by suppliers (above a DeMinimis threshold).
Trading and Settlement Code: The Trading and Settlement Code (TSC), which sets the rules for the SEM, is governed by the SEM Committee. The TSC unit within the Regulatory Authorities' offices assists the SEM Committee in this task.
High Level Market Rules: The SEM consists of a gross mandatory pool market, into which all electricity generated on - or imported onto - the island of Ireland must be sold, and from which all wholesale electricity must be purchased by suppliers (above a DeMinimis threshold).