Large scale change to Market Domain Data

Testing is required to make sure all BSC Parties will be able to load significantly larger Market Domain Data (MDD) and Line Loss Factor (LLF) files after participants provided their views on the potential impacts of adding large numbers of new Line Loss Factor Class Identifiers (LLFCs) – approximately 19,000 – and valid set combinations – approximately 300,000.

The testing is to ensure that there is not a risk to Settlement.

In August, we issued a Request for Information (RFI) so that BSC Parties could provide views on the potential impacts of adding large numbers of LLFCs and valid set combinations to MDD.

Thank you to everyone that provided their views. The vast majority of respondents highlighted risks and requested testing prior to the data being published.

Next steps

Currently, we are in the process of assessing, as a minimum, providing test files for MDD(D0269/D0270) and LLFs(D0265). We will be distributing an indicative plan to Licensed Distribution System Operator (LDSO) and Independent Distribution Network Operators (IDNOs) once the expected testing timescales have been agreed and finalised.

As a results of this, any scheduled Targeted Charging Review (TCR) Change Requests will be on hold until testing has been successfully completed.

Please note that as the current TCR submissions are on hold, this might have a knock on impact on the later stages of the current plan and may affect Distribution Network Operators (DNOs) go-live dates for the related submissions for 1 April 2021. 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.

We are currently in the process of planning for industry testing and we will confirm dates in October.

Previous progress on Market Domain Data Change requests

BSC Panel             

At the BSC Panel on 10 September 2020, the Panel considered Market Domain Data Change Requests for Version 302/303 – (306/05).

 The BSC Panel:

  • approved Change Requests M3629 and M3631 which include LLFCs to support both the TCR and other billing requirements.
  • deferred Change Requests M3630 and M3632, which only contain changes to support the TCR, until further information on the 1 April 2021 deadline and testing has been provided.

Supplier Volume Allocation Group (SVG)

At the SVG Meeting (SVG235/01) on 1 September 2020, the first set of submissions to support the implementation of Ofgem’s TCR Significant Code Review (SCR) were presented to the SVG for approval.

They considered four TCR related Change Requests, for implementation in Version 303 of MDD with a go-live date of 21 October 2020.

The SVG could not reach a decision to approve the Change Requests, so they were referred to the BSC Panel at their meeting on 10 September 2020.

Ofgem’s Targeted Charging Review

On 18 December 2019, Ofgem concluded its TCR: SCR. As part of its final decision, Ofgem directed the LDSOs and National Electricity Transmission System Operators (NETSO) to make changes to how residual Distribution Use of System (DUOS) and Transmission Network Use of System (TNUoS) network charges are set and recovered in Great Britain.

In January 2020, LDSOs and NETSO raised Distribution Connection and Use of System Agreement (DCUSA) and CUSC Modifications to give effect to the TCR: SCR Decision.


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