MDD changes initiated by Ofgem Review


Large scale changes to Market Domain Data (MDD) based on Ofgem’s Targeted Charging Review (TCR).

This page contains details about the planned increase of MDD sets in response to Ofgem’s TCR and how this will impact BSC Parties. You can also find out information about why these changes are happening, what has already happened and what the next steps are.

Latest update

18 October 2021
As part of our continuing work to progress large scale change to Market Domain Data (MDD) sets for Ofgem’s Targeted Charging Review (TCR), we have been carrying out industry and BSC Central Systems testing over recent months. Due to the unprecedented growth in the size of the MDD and Line Loss Factor (LLF) datasets needed for the TCR, we undertook this testing to identify and mitigate any potential risk to industry processes relating to balancing and settlement. 

The testing completed in August. Overall, the results gave us confidence that the Central Systems will be able to process the additional data volumes, and that our Parties’ systems would be able to cope with the increase. We provided this information to the Supplier Volume Allocation Group (SVG) at their meeting on 3 August 2021. The SVG then approved the next batch of TCR related changes for the MDD Version 315, which added 4,657 TCR LLFCs and 32,350 combinations, and which was published in September.

The SVG have since also approved the TCR related changes for MDD Version 316, which was published on 13 October 2021 and will go live on 20 November 2021, and MDD Version 317, which will be published on 10 November and will go live on 17 November. Some TCR Changes will also be included in MDD Version 318, which will be published in December. The specifics are outlined in the Publishing data section below.

How it relates to you

Ofgem’s TCR means major changes to how network charges are set. It will see the numbers of LLFCs in MDD increasing on a large scale, as well as the number of valid set combinations.

BSC Parties who load MDD and LLF files may be impacted, as they will have to load significantly larger numbers of new LLFCs and valid set combinations.

Such a large increase in data could impact your network systems. If you notice any such impact, please contact the MDD Coordinator or LLF Coordinator.

What’s already happened

Industry Testing

Test plans will incorporate testing for Participants, the BSC Central Systems, and subsequent Settlement processes as they will be using the increased volumes of LLFCs. We will provide you with a further update on the test plan as soon as we can.

We will make sure that the participants are kept informed with regards to testing and are provided with sufficient notice prior to TCR submission dates.

Reasons for testing

As this is a major change to MDD data, Elexon has been leading work to carry out central system testing and participant testing. Overall we will need to provide assurances to the SVG, the BSC Panel and BSC Parties that adding such a large amount of new data will not pose risks to Settlement.

Software development

Automatically loading MDD

Software is being developed that will automatically load MDD, as this is currently a manual process. This should reduce the risks around the publication and data quality of MDD for participants.

Publishing data

  • 15 December 2021: This is due to add 13,029 combinations and end-date 502 LLFCs and 11,687 combinations, subject to SVG approval. The go live date will be 22 December 2021.
  • 10 November 2021: The TCR related changes have been approved by the SVG and will add 1,420 LLFCs and 18,887 combinations. It will also end-date 15,721 combinations. This will go live on 17 November 2021.
  • 13 October 2021: 3,095 new LLFCs and 34,449 new valid set combinations added to MDD. This went live on 20 October 2021
  • 15 September 2021: 4,657 new LLFCs and 32,350 new valid set combinations added to MDD. This went live on 22 September 2021.
  • 13 January 2021: MDD data set was published. The data set includes the TCR changes for the remaining Host Distributed Network Operators DNOs and includes 13 out of 14 Grid Supply Point (GSP) Groups. This went live on 20 January 2021.

  • 9 December 2020: MDD data set was published, but the set did not contain any TCR changes. This went live on 16 December 2020.
  • 11 November 2020: 1,638 new LLFCs and 37,000 new valid set combinations added to MDD. This went live on 18 November 2020. 
  • 14 October 2020: 2,122 new LLFCs and 24,287 new valid set combinations added to MDD. This went live on 21 October 2020.

This new published data impacts D0269/D0270 (MDD) and D0265 (LLFC) flows.

Previous news

Why these changes are happening

Ofgem’s TCR addressed concerns that the current framework for residual network charges could lead to inefficient use of the network. This means there will be major changes to how network charges are set.

This will result in the numbers of LLFCs in MDD increasing from 16,000 to approximately 35,000. The number of valid set combinations will also increase from around 208,000 to approximately 470,000.

The distribution charge aspects of Ofgem’s reforms will be introduced from April 2022.


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