Trading Across the Moyle Interconnector

General Information

The Moyle Interconnector is a High Voltage Direct Current (HVDC) connection between Northern Ireland and Scotland. It is made up of two 250MW cables and can operate in either direction, providing a total connection of 500MW between the all-Ireland Single Electricity Market and the GB market.

Since 1st October 2018, with the arrival of the new I-SEM market on the island of Ireland, the SEM and GB markets are coupled meaning the physical interconnector flows are determined by the relative prices in the two connected markets.

This means that, instead of offering physical capacity on the interconnector to the wider market, we offer long-term transmission rights in the form of Financial Transmission Rights Options (FTRs), which give the holder the right to a financial pay-out based on the difference in day-ahead prices between the SEM and GB markets.

Separate FTRs are offered for each direction on the interconnector and are a form of one-way contract for difference, entitling the holder to receive the positive day-ahead market spread in the direction of the FTR option.

FTRs are sold via auctions. The Moyle Interconnector currently offers five types of product:

Product TypeCovers all hours between:
SEM Annual1st October to 30th September
Calendar Annual1st January to 31st December
Seasonal1st April to 30th September
1st October to 31st March
Quarterly1st January to 31st March
1st April to 30th June
1st July to 30th September
1st October to 31st December
Monthly1st to final trading day of each month

A full overview of FTRs can be found here.

Trading on the Moyle Interconnector

Financial Transmission Rights Information

These FTRs can be bought in auctions run by the Joint Allocation Office (JAO), anauction office based in Luxembourg that allocates capacity on approximately 80 borders throughout Europe.

In order to purchase FTRs for the Moyle interconnector, participants must register with JAO at least seven working days prior to the first auction they wish to participate in. This involves submitting several forms with business and financial information, and lodging collateral or a bank guarantee with JAO. Information on how to do so can be found on the JAO website. Any queries regarding registration should be directed to JAO using the contact details available here.

Auctions are run in accordance with the EU Harmonised allocation rules for long‐term transmission rights which can be found here and an auction calendar detailing dates for future FTR auctions can also be found here.

Moyle Capacity

While Moyle is technically able to transport 500MW between the two markets, due to constraints on the transmission networks at either end of the interconnector, the commercial capacity of the interconnector is lower than this.

The maximum available capacity in each direction varies throughout the year, and is given in the table below:

DirectionTime PeriodFirm capacity availableAdditional capacity potentially available from National GridMaximum capacity actually available due to SONI constraint
Northern Ireland to Scotland10th November 2017 to 30th November 2019
80 MW
420 MW295 MW

(380 MW from 2nd July 2019)
1st December 2019 to 31st May 2020307 MW193 MW295 MW

(380 MW from 2nd July 2019)
1st June 2020 to 31st October 2021250 MW250 MW295 MW

(380 MW from 2nd July 2019)
1st November 2021 ro 31st March 2022160 MW340 MW295 MW

(380 MW from 2nd July 2019)
1st April 2022 onwards500 MW0 MW 295 MW

(380 MW from 2nd July 2019)
Scotland to Northern Ireland1st April – 31st October410 MW

(450 MW from 2nd July 2019)
1st November – 31st March450 MWN/AN/A

Commercially available capacity in the Northern Ireland to Scotland direction varies day to day, depending on conditions in the GB transmission system. The process for determining this capacity is laid out in detail in this document. Broadly there is a minimum ‘firm’ export capacity which is then ‘topped-up’ by additional capacity released two days ahead of delivery by National Grid.

Further documentation detailing the rules underpinning capacity calculation and FTR allocation and compensation can be found on the Moyle Publications Page.

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