Single intraday coupling ('SIDC') creates a single European cross-zonal intraday electricity market. In simple terms, buyers and sellers of energy (market participants) are able to work together across Europe to trade electricity continuously on the day the energy is needed. An integrated intraday market makes intraday trading more efficient across Europe by:

• promoting competition,
• increasing liquidity (i.e. increasing the ease with which energy can quickly be bought and sold without affecting its price),
• making it easier to share energy generation resources, and
• making it easier for market participants to allow for unexpected changes in consumption and outages.

As intermittent renewable production such as solar energy increases, market participants are becoming more interested in trading in the intraday markets. This is because it has become more challenging for market participants to be in balance (i.e. supplying the correct amount of energy) after the closing of the day-ahead market. Being balanced on the network closer to delivery time is beneficial both for market participants and power systems by, among other things, reducing the need for reserves and associated costs.

SIDC is a joint initiative between Nominated Electricity Market Operators (NEMOs) and Transmission System Operators (TSOs) which enables continuous cross-border trading across Europe. SIDC follows on from the Cross Border Intraday ('XBID') Project which delivered the first technical solution for creating SIDC through the intraday continuous trading platform in June 2018. SIDC allows energy networks to integrate and expand across Europe and was launched on 12/13 June 2018 across 14 countries and a year later the project parties announced a successful first year of operation. The following press releases illustrate these events in more detail.

• Press_release_XBID_Go-Live.pdf
• Press_release_XBID_anniversary.pdf

The project responded to market needs by creating a transparent and more efficient continuous trading environment that allows market participants to easily trade their intraday positions across individual EU markets without the need for explicit transmission capacity allocation.

The technical solution works on a common IT system with:

• a Shared Order Book ('SOB'),
• a Capacity Management Module ('CMM'), and
• a Shipping Module ('SM').

This means that orders entered by market participants for continuous matching (supply meeting demand) in one country can be matched by orders submitted by market participants in any other country. They can be matched as long as they are within the project’s reach and transmission capacity is available.

The intraday solution supports continuous trading that is both:

• implicit (capacity and energy together), and explicit (capacity only. Note: only provided where requested by NRAs).

A public description of the continuous trading matching algorithm is available here:

Details of how SIDC works can be found under this link. SIDC is in line with the EU integrated intraday market target model set out in the CACM Regulation.

SIDC geographical scope

SIDC expands in waves. The first go-live wave was in June 2018 and included 14 countries.

On 19 and 20 November 2019, OTE, a. s., as the nominated electricity market operator in the Czech Republic, and ČEPS, a. s., as the transmission system operator in the Czech Republic, joined SIDC along with similar entities in six other European countries within the second wave go-live. This coupled 21 countries.

On 1 October 2019, a workshop on the market coupling of intraday markets within the second go-live wave was held, at which the following documents were presented:

• Set of questions and answers provided during the workshop: SIDC_Q_and_A.pdf
• Updated information package: SIDC_XBID_Information_package.pdf
• Presentation on the second wave of launch: SIDC_2nd_Wave_Pre-launch_Event_Display.pdf

A release of SIDC (Release 2.0) was deployed at the end of October 2019. This added upgrades to:

• integrate additional non-multi NEMO areas into the intraday coupling, and
• increase the depth of the SOB from 31 to 100.

The table below lists the countries that participated in the go-live in the first two waves and are planning to participate in the third wave, which is planned for the second quarter of 2021.

An updated versionof SIDC (Release 2.0) was deployed at the end of October 2019. This added upgrades to:

• integrate additional non-multi NEMO areas into the intraday coupling, and
• increase the depth of the SOB from 31 to 100.

In April 2021, a new version of SIDC (Release 3.1) was launched. Thanks to the improvement of the system, it is possible to fulfill the obligations arising from the current valid legislation, especially the publication of operational data. The new version also helped to improve the day-to-day usability of the system.

To accomplish the SIDC, TSOs and NEMOs work in close collaboration.

Market information

Figure 1 - Completed and planned waves of SIDC enlargement (available on the NEMO Committee website here)

Parameters of intraday trading are listed here.

Future development

The development of SIDC is important to all parties (NEMOs and TSOs) involved in the project. Here we list future developments to expand and improve the efficiency of the SIDC:

1. Plans are underway to implement functionality to address losses on HVDC cables.
2. Plans are underway to integrate cross-zonal capacity pricing through auction needs in line with ACER’s decision on establishing a single methodology for pricing intraday cross-zonal capacity.
3. Plans are underway to implement cross-product matching into the system. This will enable the matching of different products with one another (for example 15 min with 60 min orders).
4. In the longer-term, Flow-Based allocation and non-standard intraday products are two areas that need to be addressed.