Slovenská elektrizačná prenosová sústava, a.s. (SEPS) actively participates, in line with its mission and corporate vision, in activities that contribute to the development of both the pan-European and the Central European electricity market. Cooperation among European transmission system operators (TSOs) is carried out through institutionalised entities such as ENTSO-E, JAO S.A., TSCNET Services GmbH, and others, as well as through implementation projects related to network codes and guidelines. As a responsible TSO with many years of experience, SEPS prioritises efficiency, long-term sustainability, and corporate social responsibility in compliance with applicable legislation.
ENTSO-E
ENTSO-E (European Network of Transmission System Operators for Electricity) is an international association headquartered in Brussels. It was established by transmission system operators (TSOs) in December 2008 pursuant to Regulation (EC) No 714/2009 on conditions for access to the network for cross-border exchanges in electricity. It currently brings together 40 TSOs from 36 European countries. As a founding member of ENTSO-E, SEPS actively contributes to the work of the association’s working groups and governance bodies through its appointed representatives.
ENTSO-E’s key responsibilities, arising from its legal mandates, include:
- developing and implementing standards, network codes, platforms, and tools to ensure the secure operation of the power system and electricity market, as well as the integration of renewable energy sources into the grid,
- assessing system adequacy,
- coordinating infrastructure planning and development at the European level through the Ten-Year Network Development Plans (TYNDPs),
- coordinating research, development, and innovation activities among TSOs,
- developing platforms for transparent data sharing with market participants.
TSCNET Services GmbH
TSCNET Services GmbH, headquartered in Munich, provides services to transmission system operators and their control centres to maintain the operational security of the interconnected power system on a 24/7 basis. It is one of the six Regional Coordination Centres (RCCs) and, in accordance with Regulation (EU) 2019/943 on the internal market for electricity, has been providing the following RCC services since 1 July 2022:
- coordinated security analysis
- coordinated capacity calculation
- outage planning coordination
- short-term and medium-term adequacy assessments
- common grid model
- coordinated support for emergency and restoration states, including defence and restoration plans
- support in managing critical network situations
as well as the development and subsequent provision of additional services arising from the above-mentioned Regulation.
Currently, 16 European TSOs are shareholders and the principal customers of TSCNET Services GmbH. SEPS has been a shareholder of TSCNET since June 2018.
JAO S.A.
JAO (Joint Allocation Office) is a service company headquartered in Luxembourg that performs the following activities on behalf of transmission system operators (TSOs):
- annual, monthly, daily, and intraday explicit auctions for the allocation of cross-border transmission capacity rights on both internal EU borders and borders with non-EU countries,
- daily explicit shadow auctions, which serve as a fallback mechanism when the Single Day-Ahead Coupling (SDAC) process is unable to produce results,
- clearing, settlement and contractual administration,
- reporting, project support and IT-related services.
Since October 2018, JAO has served as the pan-European platform for the allocation of long-term transmission capacity—the Single Allocation Platform (SAP).
JAO’s shareholders are 26 TSOs from Europe. In 2008, SEPS was a founding shareholder of CAO (JAO’s predecessor which was established in 2015 through the merger of CAO and CASC.EU).
REGIONAL ACTIVITIES
CORE CCR
The CORE Capacity Calculation Region (CORE CCR) is a capacity calculation region comprising 16 European TSOs and covering a substantial part of Europe. It was established by ACER Decision No. 06/2016 of November 2016. At its level, procedures and methodologies are developed regarding the optimization of transmission capacity, cross-border trading and operation of interconnected transmission systems, while maintaining the maximum level of security of supply, as required by the relevant network regulations and guidelines. This primarily includes the development and implementation of methodologies for:
- flow-based capacity calculation for the long-term, day-ahead, and intraday timeframes,
- coordinated redispatching and countertrading to alleviate congestion within the interconnected transmission system.
CE CCR
The Central Europe Capacity Calculation Region (CE CCR) is a new capacity calculation region created by extending the geographical scope of the former CORE CCR to include the Italy North bidding zone border. This extension was approved by ACER as part of the amendment to the capacity calculation region designation under Article 15 of Commission Regulation (EU) 2015/1222 (CACM). It reflects the increasing level of interconnection and the strong operational interdependencies between the Central European and Northern Italian transmission systems.
CE CCR has been designed as an evolutionary extension of CORE CCR, with the integration of the Italy North border being implemented progressively across individual timeframes. In the first phase, the common capacity calculation methodology will apply exclusively to the day-ahead timeframe, while the implementation of coordinated capacity calculation for the intraday and long-term timeframes, together with further regional integration, is planned for subsequent phases, subject to technical readiness and operational stability. Although this phased implementation approach may simplify certain aspects of the process, it also gives rise to a number of implementation issues (such as ensuring consistency between the day-ahead market processes and the long-term timeframe) which have not yet been fully resolved at the conceptual level.
Unlike CORE CCR, which is entirely based on the flow-based capacity calculation methodology, CE CCR places greater emphasis on a carefully managed transition and on minimising risks to system operational security. Particular consideration is given to the specific characteristics of the Italian power system, the significant role of HVDC interconnections, and differences in network topology. The objective of CE CCR is to establish a unified and consistent capacity calculation region across a significant part of Europe, enabling further improvements in market efficiency while maintaining a high level of operational security.
CORE FB MC
The project for coupling day-ahead markets based on the flow-based method in the CORE region (FB MC – Flow-based Market Coupling) represents a key element of the single European electricity market in accordance with Commission Regulation (EU) 2015/1222 (CACM).
The flow-based capacity calculation process represents a method where the physical network limits are based on the available margins on critical network elements and power transfer distribution factors, which are defined for each critical network element and each bidding zone within the CORE region.
The CORE FB MC project was successfully put into operation in 2022 as part of the Single Day-Ahead Coupling (SDAC) and has since represented the standard mechanism for the allocation of cross-border capacity in the CORE region.
Following the day-ahead market, the flow-based approach was gradually introduced into the intraday market through the system for calculating intraday cross-border transmission capacity – Intraday Capacity Calculation (IDCC).
- In 2024, the IDCC(a) step was launched, which makes available the capacities remaining after the day-ahead market without recalculating them. Subsequently, the IDCC(b) step was introduced, in which the capacities are already recalculated using the flow-based model.
- In 2025, the IDCC(c) step was added, which ensures further recalculation of capacities in the early morning hours on the day of delivery based on a more up-to-date state of the network.
- In 2026, the IDCC(d) step was also introduced, which was successfully launched on 28 April 2026 and brings a further capacity calculation during the day based on the latest available data.
The gradual introduction of these steps makes it possible to continuously update the available transmission capacity according to the current state of the transmission system. The result is more efficient use of the network, improved market responsiveness to changes and an overall improvement in the functioning of the intraday electricity market.
SDAC/SIDC
The single European electricity market is based on the coupling of day-ahead and intraday markets through the Single Day-Ahead Coupling (SDAC) and Single Intraday Coupling (SIDC) projects, which together form the basis of efficient cross-border trading in Europe.
SDAC ensures the coupling of day-ahead electricity markets across Europe and enables market participants to trade electricity for the following trading day throughout Europe. Cross-border capacities are allocated automatically through a single algorithm that takes into account the technical constraints of the transmission system and ensures their most efficient use. The result is an increase in market liquidity, more efficient use of generation resources and a reduction in price differences between individual countries.
Slovakia, through SEPS and the short-term electricity market operator, which is OKTE, has been part of the Single Day-Ahead Coupling (SDAC) since 2022 with the launch of the CORE FB MC project.
Building on SDAC, the Single Intraday Coupling, SIDC, which enables continuous electricity trading during the day up to the time of delivery. This market provides participants with the possibility to respond flexibly to current changes, for example fluctuations in generation from renewable sources or unplanned outages. SIDC is based on the technical solution of the XBID project and operates as continuous cross-border trading, which was supplemented by intraday auctions (IDA) in 2024.
Intraday auctions support competitiveness in the areas of electricity generation, trading and supply by optimising the allocation of cross-border capacities and ensuring fair and non-discriminatory treatment of market participants. The implementation of intraday auctions throughout Europe is a key milestone for the completion of the single European electricity market.
Project IGCC (International Grid Control Cooperation)
The objective of the IGCC (International Grid Control Cooperation) implementation project is to create a European platform for the process of exchanging/netting imbalances in real time (Imbalance Netting) within the meaning of Regulation (EU) 2017/2195 establishing a guideline on electricity balancing.
SEPS has been an active participant in IGCC since May 2020.
FCR Cooperation Project
The FCR Cooperation Project is a joint project with the voluntary operational participation of currently 12 transmission system operators, which enables the joint procurement of frequency containment reserves with automatic frequency control. The FCR Cooperation Project is in accordance with Commission Regulation (EU) 2017/2195 (EBGL), with the objective of creating a common market for the procurement and exchange of FCR in the EU.
SEPS officially joined the FCR Cooperation as an observer on 2 February 2023.
CMM Module
CMM (Capacity Management Module) is an external module that ensures the forwarding of information between platforms, capacity calculations for individual platforms and, on the basis of these data, determines the available cross-border capacities. These are subsequently provided to the European platforms for the exchange of balancing energy, MARI, PICASSO, and to the IN (Imbalance Netting) platform. The module is managed by the Czech transmission system operator ČEPS.
SEPS successfully connected to the CMM module on 29 October 2025.
MARI and PICASSO Projects
The objective of both implementation projects is to create a European platform for the exchange of balancing energy from manually activated frequency restoration reserves (Manually Activated Reserves Initiative – MARI) and automatic activation (Platform for the International Coordination of Automated frequency restoration and Stable System Operation – PICASSO) within the meaning of Commission Regulation (EU) 2017/2195 (EBGL).
The MARI project was established in April 2017, while SEPS joined it on 26 June 2018 and thus became a full member. The official website of the MARI project, including information on the current status of the project, is available on the ENTSO-E website, where you can also find the current connection status and the connection plan of the other transmission system operators (TSOs), the so-called accession roadmap.
The connection of SEPS to the MARI platform was successfully completed on 3 December 2024.
The PICASSO project was established in August 2017, while SEPS joined it on 26 June 2018 and thus became a full member. The official website of the PICASSO project, including information on the current status of the project, is available on the ENTSO-E website, where you can also find the current connection status and the connection plan of the other TSOs, the so-called accession roadmap.
The connection of SEPS to the PICASSO platform was successfully completed on 5 November 2024.
OTHER GROUPINGS:
TSC (TSO Security Cooperation)
TSC (Transmission System Operator Security Cooperation) represents a platform for regional cooperation of TSOs with the objective of improving the operational security of the transmission systems of the participating countries. The most significant initiative of TSC was the establishment of TSCNET Services GmbH.