This section answers questions on the Markets, along with information relating to the Systems Implementation, SEMOpx, Market Readiness, and Market Rules.

General information

If you are new to the I-SEM Project and need to find out information, you will find background, training, calendar events and learning resources in this section.

The wholesale market on the island is due to change considerably to take account of the requirements of the European Network Codes and the Target Model, including a change to four market timeframes. This will be the new I-SEM (Integrated – Single Electricity Market) market design key elements of which include:

  • Active participation by supplier companies – submitting bids to purchase energy in the day-ahead and intraday markets.
  • Suppliers and generators paying / being paid based on prices and quantities determined through ex-ante (forward, day-ahead and intraday) trading.
  • Cross-zonal power flows determined based on energy market trades and power flowing from the cheaper to the more expensive bidding zone.

You can contact the I-SEM Project by emailing the I-SEM Project helpdesk at For additional information on how to contact the I-SEM Project, please see our Contact page.

The I-SEM Project is working with the RAs and Participants to ensure everyone is ready in time for Go-Live. The I-SEM Project has established the following 4 working groups to liaise with participants to keep participants informed and to address any issues raised:

  • Market Rules Working Group (RWG) - An established group of participants, ISEM project and Regulatory staff working to finalise the rules for the new market.
  • Project Managers Group (PMG) - This group mainly works through the Project Plan/Key Milestones, Schedules and Readiness.
  • Technical Liaison Group (TLG) - Technical Design, System Communications and Readiness.
  • Business Liaison Group (BLG) - Business, Functional & Process Readiness. These differ per subject matter, there have been two to date one on AOLR (Aggregator Of Last Resort) and one on NEMO (Nominated Electricity Market Operator).

The upcoming I-SEM events are located in our Calendar. Simply click on the event you are looking for or filter by event category.

Yes, all of the Liaison Group meetings will be available via MS Lync Web Conference. We ask that all participants who have not checked their Lync connectivity with us and wish to do so, please request a test with The Lync Web Conference information will be emailed to you once you have registered to attend the meeting.

Additional information and updates can be found in the I-SEM calendar under each meeting scheduled. View the External Access Guide to I-SEM Lync Meetings for reference.

All documentation relating to the I-SEM Project are located in Publications. Simply filter by Name, Category, Document Type, Date or Subcategory.

The I-SEM Project Market Readiness programme of work is an integral part in the delivery of a Market Go-Live Decision. As such, each organisation have been asked to nominate a Participant Readiness Coordinator (PRC) to be the primary point of contact for the Market/Participant Readiness and the Project Managers Group.

The PRC is responsible for the following:

  • Determine the readiness criteria for their organisation, and the milestones within each criterion which are relevant to their organisation
  • Assess progress against the defined readiness criteria
  • Take any other actions necessary to ensure readiness for participation in the market
  • Attend and engage with the Project Managers Liaison Group
  • Ensure any I-SEM Updates, Change Requests/Impact Assessments or important notices etc. are communicated to the appropriate people within their organisation
  • Address any issues and/or concerns related to readiness - arising from the readiness assessment, or otherwise identified by the participant or the I-SEM Project

If you would like to nominate a Participant Readiness Coordinator from your organisation, please email the following information to

Organisation details

  • Organisation
  • Associated Party / Parties

PRC details and alternate PRC details

  • Name
  • I-SEM role
  • Phone number
  • Email address

For more information, please see the Terms of Reference for the PMG.

The Technical Liaison Representative (TLR) is the point of contact for the Technical Liaison Group.

The TLR is responsible for the following:

  • Attend and engage with the Technical Liaison Group
  • Ensure any I-SEM updates on technical systems or important notices etc. are communicated to the appropriate people within their organisation
  • Address or raise any issues and/or concerns related to systems readiness at the Technical Liaison Group

If you would like to nominate a Technical Liaison Representative from your organisation, please email the following information to

Organisation details

  • Organisation
  • Associated Party / Parties

PRC details and alternate PRC details

  • Name
  • I-SEM role
  • Phone number
  • Email address

For more information, please see the Terms of Reference for the TLG.

The SEM Agreed Approach document requires that a Change Control process must be approved by the I-SEM Steering Group. This process should be in line with recognised industry standards.

To comply with this overall requirement for I-SEM Programme delivery, a standard process is needed to manage all proposed changes to the baselined programme time, cost or quality, which impact on two or more parties within the overall programme.

In this context:

  • Baselined time = unrecoverable slippage to any milestone on the Level 2 programme plan (and by inference, also Level 1 milestones)
  • Baselined cost = any proposed variance from the agreed financial envelop for the I-SEM Programme
  • Baselined quality = the scope and functionality of the I-SEM, as set out in the design documentation and specifications to be baselined Dec 2015 onwards, on which two or more parties depend

A party is any one of:

  • CER and UR, acting jointly
  • TSO – in its delivery role
  • The Interconnector Owners (ICOs) – in their delivery roles
  • Any other stakeholder involved in the I-SEM Programme e.g. TSO in any other role, generators, suppliers

The Change Control process should not be used for non-baselined documentation or management products such as minutes of meetings, or interim products such as working papers, registers or action lists; these changes should be managed ‘internally’ by the various workstream managers and PMO.

The Regulatory Authorities have overall responsibility for defining and maintaining the Change Control procedure, and changes to it will be managed through the RA I-SEM Project Office.

For detailed information on this process, please see the Programme Change Control Procedure document.

The guide is technically correct because in this context “participate in the balancing market” refers to actively submitting incremental and decremental bids to the TSOs. 

Note the definition of Balancing Market provided in the Trading & Settlement Code states that this “means the arrangements under this Code that provide for the market-based management of System Operator actions and processes to balance continuously generation and demand and to maintain the stable and secure operation of the electricity transmission systems on the island of Ireland”. 

This naturally precludes non-dispatchable and non-controllable units as they are not subject to System Operator dispatch. This does not preclude non-dispatchable and non-controllable units from participation under the Trading & Settlement Code in relation to imbalance settlement and other requirements. We recognise that this language may lead to some confusion where the term balancing market has sometimes been used as a synonym for the balancing and imbalance settlement arrangements. This text could also read “A non-dispatchable and non-controllable unit cannot submit bids and offers to the TSO in the balancing market”.


This section covers registration for a number of Markets, including Day-Ahead, Intraday, and Balancing.                    

Registration is the process of ensuring Parties and their Units are enrolled in a timely and correct manner for participation under the new I-SEM arrangements. A Party will need to register for each market they wish to participate in. For some markets, an existing SEM Party will be required to go through a transitional registration process to ensure they remain active in I-SEM. For other markets new registrations will be required.

For more information on I-SEM Registration, please see the I-SEM Registration Webpage here. If you have further queries or feedback, please contact Claire Breslin at

The Know Your Customer (KYC) process is completed by ECC for each Participant wishing to join the Day-Ahead/Intra-Day Markets (DAM/IDM). The process asks for information from the participant related to their company. ECC evaluate this information to ensure the legitimacy and adequate financial and legal standing of the company before entry to the DAM/IDM markets is allowed. 

Participants are requested to register their interest in becoming a Participant in the DAM/IDM markets with the I-SEM Registration Team via email to by the 31st December 2016. This involves contacting the I-SEM Registration Team and confirming that you may wish to have involvement in the DAM/IDM markets. The I-SEM Registration Team and ECC will then follow up with you to discuss any potential setup considerations and questions you may have.

There is no requirement to complete the KYC forms by the 31st December 2016. However, we would recommend that the KYC application form is completed as soon as sufficient details are known of the proposed registration. Completed KYC forms will need to be provided, at the latest, with the other ECC forms by the deadline of 7th August 2017.

Download the Know Your Customer (KYC) form for Non-Clearing Members, t. For more information on the KYC form, please see the ECC Webpage. If you have further queries with regards to the KYC form, please contact Anke Voigt at

Participants are asked to nominate a ‘Registration Contact’ for each Party to allow direct communication on registration related topics and the registration process. Please submit details of the Registration Contact details by email to

Based on the latest drafting of the Trading and Settlement Code (TSC), the following describes how credit cover will be calculated for each Participant.  The Required Credit Cover (RCC) of a Participant will be determined based on the following components. It will be calculated for both Balancing and Capacity together.

  1. Actual Exposure – Consisting of both Settlement Documents that have been issued but not yet paid, as well as settled days that have not yet been included in a Settlement Document.
  2. Traded not Delivered – Amounts traded in the DAM/IDM that have not yet been physically delivered (i.e. have not been settled in the Balancing Market).
  3. Undefined Exposure – The forecast of the future exposure of the Participant, which has not yet been traded.
  4. Fixed Credit Requirement – For resettlement exposures.
  5. Settlement Reallocation Agreement (SRAs) Transfers – To allow for SRAs that have been put in place to transfer financial obligations between Participants.

The RCC will be the summation for all units (i.e. Generation, Assetless and Supply) under the same Participant to determine the RCC. Where the exposure of a unit reduces the exposure of the Participant to the market, this will be included as a ‘credit’ in the RCC calculations.

An invitation for upcoming events will be sent out to all participants signed up for I-SEM Alerts. Please see a quick guide here for step-by-step instructions. Alternatively, for more information on the next I-SEM Registration events, please see the I-SEM events located in our Calendar. Simply click on the event you are looking for or filter by event category. You can register to attend the event by emailing

Participants are asked to nominate a ‘Registration Contact’ for each Party to allow direct communication on registration related topics and the registration process. Please submit details of the Registration Contact details by email to

The current timelines are detailed in the Transitional Registration Plan. Additionally, the High Level Overview and Detailed Diagrams can also be found in the Transitional Registration Plan. Any updates to these documents will be communicated to participants via the Liaison Group events.

If you have any queries regarding I-SEM Registration, please email Claire Breslin at

All documentation relating to I-SEM Registration are located in General Publications.

Specific trader requirements are accounted for by the exchange rather than by the clearing house. In this case, SEMO will produce a set of NEMO market rules (currently in development through NEMO BLG meetings) and this will account for any specific requirements. The specific requirements, if relevant, are a local NEMO market rule which is determined by each exchange. In relation to this question, previous experience should be included but there will be no prerequisite linked to this form specifically.

A Non-Clearing Member (NCM) is always registered as a Legal Entity. This would more than likely relate to a Party under the Balancing Market as a Party must be a legal entity.

One legal company can be setup with two different Member IDs but please note that both IDs are not allowed to trade the same product. Typically the split is made because of using different clearing members for Spot and Derivatives Market or between different exchanges.

The setup of the ‘members’ in the Day-Ahead/Intra-Day Markets does not need to match the setup of Parties and Participants in the Balancing Market. It is possible to have a different legal entity trading the units in the Day-Ahead/Intra-Day markets to that setup in the Balancing market once the appropriate agreements are in place. Also, in other energy markets they tend to use portfolios to represent groups of units.

For the I-SEM this is not the case as the market design dictated that all trading shall be at a unit level. Therefore, trading for both the Day-Ahead/Intra-Day and Balancing Markets will be done at a unit level. This means, all Day-Ahead/Intra-Day results will be transferred and applied at a unit level for the balancing/imbalance settlement and for credit cover calculations in the balancing market.

There is no process at ECC to register with clearing banks. Please contact a potential clearing bank directly to get all your questions answered. Please find here a list of all clearing members registered at ECC.

The I-SEM Balancing Market / Capacity Market Design is based on a wholesale pool concept. In this context SEMO as the Market Operator does not take title to the energy as part of the buying and selling of energy in the Balancing Market / Capacity Market.

As approved by the Revenue Authorities of both the Republic of Ireland (ROI) and United Kingdom (UK) jurisdictions, SEMO calculate VAT amounts for the purposes of Participants completing VAT returns. These VAT amounts are based on the proportion of energy charges and payments in the Balanicng Market / Capacity Market relative to the place of establishment for VAT purposes of the buyer or seller.

For determination of the applicable VAT treatment, SEMO need to know who is the party to the transaction and where they are established for VAT purposes. i.e. the legal entity who is buying and the legal entity that is selling in the associated transaction and where these legal entities are established for VAT purposes. Parties in the I-SEM are required to provide their place of establishment for VAT purposes as part of the registration of the Party and its Participants.

Parties do not have to provide proof of the place of establishment for VAT purposes to SEMO. It is each Party’s responsibility to ensure that the correct place of establishment for VAT purposes is provided so that the corrrect VAT treatment is applied to the transactions. Where a Party has doubt over where it is established for VAT purposes, they should seek professional taxation advice considering the significant VAT consequences that such a position may have.

This is governed by legislation and case-law of the Court of Justice of the European Union.
Broadly speaking, an establishment for VAT purposes exists in the country where the functions of the business’s central administration are carried out i.e. the place where:

  • The essential decisions concerning the general management of the business are taken
  • The registered office is located
  • Management meets

The above sets out factors which should be considered when determining where a business is established for VAT purposes. However, in instances where one or more of the above factors is not present, a VAT establishment in a jurisdiction may still exist. Each case should be assessed on its own merits.

A Party should provide its VAT registration number for the jurisdiction in which it is established for VAT purposes in relation to the supply/purchase of energy in the Balancing Market and Capacity Market.

In the Balancing Market:

Capacity Charges, Imperfections etc are not paid by the TSSU unless the trading site - which contains both the TSSU and GUs-  is a net importer from the grid. If the generators are running and TSSU demand is less than this generation (hence the site is a net exporter), then you should not incur these charges.

Market Operator Charges are still relevant if you have a TSSU and are not dependent on the net import or net export from the trading site.

In the Day Ahead and Intraday Markets (DAM/IDM):

There are a few different scenarios for how Trading Sites, TSSUs and Generator Units could interact in the DAM/IDM. Take for example the setup of a GU (100MW) before house load, and TSSU (5MW) under the same trading site.

Scenario 1: Net Export from the Trading Site

In this case metering will show a quantity against the GU (95)  and nothing against the TSSU. So to avoid an imbalance you would need to trade the net export of 100-5 = 95MW against the GU in the DAM

Scenario 2: Net Import from the Trading Site (ie. GU off line)

In this case the metering would show 5MW demand on the TSSU and nothing on the GU. To avoid an imbalance you would need to trade either:

  • 5MW against the TSSU in the DAM, or 
  • 5MW(purchase) against the GU in the DAM

For the first option, the imbalance on the GU and the imbalance on the TSSU would be zero.

For the second option, there would be an imbalance on the GU  due to the contract in the DAM which would be offset against an imbalance the other way on the TSSU. This would be cost/profit neutral as the imbalance price paid and received would be the same when you consider revenues across both units.

Scenario 3: An associated Supply Unit (ASU) instead of TSSU

In this case, scenarios 1 and 2a apply with the ASU substituted for TSSU. i.e. the ASU will need to trade in the DAM when the trading site has net import, but not when the trading site has net export.

Based on legal review of the trust arrangements for the SEM/I-SEM and potential issues during default and credit call scenarios, the collateral requirements  for Participants under SEM and I-SEM will need to be maintained separately.

This means that separate Letters of Credit and separate collateral reserve accounts will need to be defined for I-SEM. A new deed of charge will also be required as the deed is specific to the collateral account.

A Having an Assetless Unit registered in the I-SEM will not allow interconnector trading as currently occurs in the SEM. Interconnector traders are not a feature of the I-SEM design. The design of the I-SEM involves the following components related to interconnector trading.

Financial Transmission Rights

Auctions run by the Joint Allocation Office (JAO), on behalf of the Interconnector Owners, to allow FTR holders to receive the congestion rents from the interconnector. This congestion rent will be provided from the revenues received where there is a different in price exists in the Day-Ahead market between the SEM and UK markets due to congestion of the interconnector i.e the interconnector is fully utilised.

Participants wishing to be involved in this market must register with JAO to trade in this market. Visit the JAO registration website or email or to contact the Interconnector Administrators.

Day-Ahead and Intraday Trading

Unlike the existing SEM, under the I-SEM design there are no physical transmission rights (either from explicit auctions prior to the trading day, nor from implicit auctions as part of intraday trading). In the I-SEM participants trade in the SEM, the market coupling between SEM and the rest of Europe determines the amount of generation and consumption scheduled in the SEM and from this the net flow of power over the interconnectors.

A single shipper then manages the physical and financial flows on the interconnectors with any revenues earned from the Day Ahead price difference between coupled market going the FTR holders mentioned above. This means the Interconnector Trader is no longer relevant for I-SEM and a Participant will not be able to register as an Interconnector Trader in I-SEM.

The Assetless Unit is a virtual unit in the I-SEM. They allow trading in the Day-Ahead and Intraday markets by Participants that do not have physical generation units nor have a supply unit with customer demand, but may wish to trade between the different I-SEM market timeframes, helping with liquidity and price formation. Assetless Units are required to register a unit in the Balancing Market to enable settlement of any imbalances should they not fully close out their positions in the ex-ante markets.

For balancing and capacity, settlement will be performed at a Participant level, not Party (PY) level as it must be jurisdictional, and not Account (old PT) as this concept is no longer used as sales/purchases can appear on the same settlement document.

  • Settlement for balancing and capacity is now more about sales/purchases rather than supplier/generator.
  • Settlement calculations sales/purchases will be performed at a Unit level.
  • VAT amounts are intended to be calculated at a Participant level for each billing run [e.g. initial, M+4, M+13 etc] and will be calculated and shown separately for sales and purchases in the Invoice.
  • As the balancing market will not be trading the full generation or demand volumes, but only the balancing/imbalance volumes, the determination of the VAT proportions for local, rest of EU and non-EU is to be based on the sales/purchase amounts rather than net demand/generation [subject to confirmation by HMRC and Revenue].

Market systems

This section covers Market Systems including general information on the Technical Specification Volumes, new publications, TLG related information and market system updates.

The I-SEM Technical Specification (ITS) comprises a set of document volumes that evolve over time with the design, implementation, and updates to the market. It contains functional and technical information related to interfaces, reports, and connectivity requirements. The I-SEM Project will publish the volumes as the programme progresses. Please see here for the publications of the Technical Specification Documents.

Yes, between I-SEM Go-Live and SEM Decommissioning, parallel running will exist. The SEM MPI will operate with reduced functionality after I-SEM Go-Live, before being decommissioned.

Participants who are accessing the Balancing Market via Type 2 interfaces will require two independent forms of authentication – a valid digital certificate and an application password. Type 3 interfaces will not require an application password. However, the existing certificate password method will continue to be used for digitally signing market submissions. Specific information can be found here.

Specific details regarding Balancing Market security and user management may be found in the I-SEM Technical Specification (ITS): Volume B.

For the Balancing Market, backward compatibility cannot be supported for I-SEM. TLS 1.1 (transport mechanism) and SHA1 (digital signature encryption algorithm) are vulnerable to attacks. TLS 1.2 and SHA2 with RSA will be used.

Note: The I-SEM security standards have been upgraded in line with best practice following identification of vulnerabilities with previous standards.

  • For the Balancing Market, SHA2-512 will be used.
  • For the Day-Ahead and Intra-Day Markets, SHA2-256 will be used.
  • For the Capacity Market, SHA2-256* will be used.

*Work remains ongoing with vendors

Registration for ETS will be part of the overall registration process which is still under development. Whilst application forms are not ready for publication, links to current EPEX and ECC forms are available on their websites. Credentials and certs will not be available until after all testing has been completed and members have been registered with the NEMO.

The mechanism for members to engage with the Spot Market Settlement System (SMSS) is detailed in I-SEM Technical Specification Volume D available on the I-SEM website. Members will be provided with access to the SMSS after all testing has been completed and members have been registered with the NEMO. Please view the publications of the Technical Specification Documents.

Market rules

This section covers Market Rules including general information on Market Codes, new publications and market updates.

As outlined in the SEMOpx Market Design Document, the auctions and continuous market of SEMOpx are run each and every day (including weekends and bank holidays). Bids can be entered anytime between the order book opening (gate opening) and the order book closing (gate closure).

In the case of the Auctions

Each auction opens 19 days before the delivery date (i.e. the date on which the energy is delivered to the system) so this would allow for early entry to take account of weekends and bank holidays.

In the case of the Continuous Market

The nature of this kind of market does not owe itself to early opening (i.e. as opposed to an auction which gathers all orders until the order book closes and solves for all orders simultaneously, a continuous market continuously matches orders in real-time). As such, the Continuous Market will open each day for the following day.

Please note that each market segment (DAM/IDM/Continuous) is voluntary so a participant would not be obliged to take part in any or all. Whether a participant decides to take part, and when they wish to submit bids is up to their own operational decisions (allowing for the gate opening and closing times described above).

A weekday which is not a public holiday, bank holiday or non-processing day as advised by the SEM Bank in Ireland or Northern Ireland. The term “Non-Working Day” shall be construed accordingly.

Holidays in either jurisdiction must be considered as Non-Working Days for all Markets:  Balancing, CRM Capacity Remuneration Mechanism, Day Ahead or Intra Day.
The Market Operator will publish on a yearly basis a Settlement Calendar detailing the status of each day and highlighting the known activities that are planned to take place in each Working Day, including Payments deadline, publication of Statements etc.

This is done in accordance to the relevant timetables set out in both the Trading and Settlement Code and the Capacity Market Code.