The Legacy Single Electricity Market (SEM) was the wholesale electricity market for the Republic of Ireland and Northern Ireland from November 2007 to September 2018. The Integrated Single Electricity Market (I-SEM) project delivered the new SEM arrangement which took over from the Legacy SEM in October 2018. This section allows you to find legacy information about the SEM.

Trading in the Legacy SEM

Discover who could trade in the Legacy Single Electricity Market, and the rules that underpinned the market operation.

Explore Legacy SEM trading about Trading in the Legacy SEM

Legacy SEM FAQs

Our FAQ section covers a variety of information to help understand how the Legacy SEM operated.

See the FAQs about Legacy SEM FAQs
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Dynamic Reports

View legacy market data in online charts and tables or download it for your own use.

Find out more about Dynamic Reports
ISEM

Historic Modifications

See closed legacy modifications which came into effect prior to the I-SEM launch.

Find out more about Historic Modifications
A Library

Publications

Download legacy documentation relating to the Legacy SEM and the I-SEM market trial.

Find out more about Publications