The transition from SEM to I-SEM took place on 1st October 2018.


The Integrated Single Electricity Market (I-SEM) is a new wholesale electricity market arrangement for Ireland and Northern Ireland. It replaced the Single Electricity Market (SEM) which had been in place since 2007. The SEM is a centralised, unilateral market which generators sell power into and suppliers buy it from. On the 1st October 2018 the SEM transform into the I-SEM.

The I-SEM involves significant changes that seeks to harmonise electricity markets across Europe as part of the European Target Model. The new arrangements will replace the current centrally organised system with multiple financial and physical markets and auctions each spanning different trading time frames (day ahead, intra-day, and balancing market), with separate clearing mechanisms.

The design of the I-SEM will impose a new level of responsibility on generating participants to become balance responsible; that is to forecast and trade efficiently. Participants unable to do this risk punitive imbalance charges. This creates new challenges and risks for generators, dramatically altering the way they interact with the market.

Through Erova Energy’s experience of trading in the coupled markets of Great Britain and continental Europe we are ideally placed to navigate the complexities inherent in the new market and to offer a range of services in support of I-SEM participants.

Further reading on the initial days of the I-SEM can be found in our insights posts: Day 1: I-SEM goes live & Week 1: I-SEM and the Wind factor.