Design Working Group

The ELEXON-led DWG has designed the Target Operating Model (TOM) for Market-wide Half Hourly Settlement (MHHS), as well as the approach for transitioning from the current Settlement arrangements to the TOM. The TOM is a key output of Ofgem’s Significant Code Review (SCR) on Electricity Settlement Reform.

Following Ofgem’s preliminary approval of the DWG’s final report (see below), this group has stood down. On behalf of the DWG, we thank everyone who inputted to its work. You can still find the DWG’s outputs and meeting papers on this page.

Further TOM development work will be undertaken by two new industry working groups during 2019-2020, both chaired by ELEXON under SCR governance: the Code Change and Development Group and the Architecture Working Group. We will publish more information about these groups soon.

What’s new?

DWG’s TOM receives Ofgem’s preliminary approval

On 1 October 2019, Ofgem published its preliminary decision to approve the DWG’s preferred TOM and its transition approach.

This decision is not final. Ofgem will continue to gather information and feedback before publishing its final decisions in Q3 2020.

About the DWG’s work

The DWG has developed the TOM in two stages:

Stage 1:

In this stage, the DWG developed and assessed a set of ‘skeleton’ TOMs. The output was a report to Ofgem on 4 April 2018, setting out the five skeleton TOMs to be taken forward for industry consultation. The consultation was issued on 30 April 2018 and closed on 29 May 2018. Click here to read the collated consultation responses.

The responses showed all five TOMs to be viable options and that the DWG had not missed any other TOM or significant aspects of design. They showed no consensus on an overall preferred TOM. The DWG therefore took all of the TOMs forward for further design and evaluation in Stage 2.

Stage 2:

This stage comprised development of both the final high-level TOM design and a high-level transition approach.

TOM design

Between April 2018 and January 2019, the DWG developed high-level service requirements for the TOMs, evaluated the different TOMs and delivered a single preferred TOM to Ofgem. On 15 February 2019, Ofgem published the DWG’s report on its preferred TOM for MHHS.

You can also find supporting information to the DWG’s TOM report here. This contains the contents of the report’s Attachment A, but separated out by the individual services within the TOM. 

The DWG consulted on its report from 18 February 2019 to 15 March 2019. Click here to read the public consultation responses. The responses validated the overall approach and coverage of the TOM design, and resulted in no fundamental changes to the TOM.

Transition approach

From January to May 2019, the DWG developed its high-level approach for transitioning from the current Settlement arrangements to the TOM. It consulted on this from 7 June to 8 July 2019. The responses validated the DWG’s transition approach, resulting in some minor clarifications but no changes to the approach itself. Click here to read the public consultation responses.

Final report

On 30 August 2019, the DWG submitted its final Stage 2 report to Ofgem. This concluded both Stage 2 and the DWG’s work under its Terms of Reference. Click here to read the DWG’s final report.

How the DWG fits into Ofgem’s SCR process

Development of the TOM forms one of several work streams in Ofgem’s wider SCR. Ofgem will make the final decision on the TOM and transition approach.

Ofgem’s other parallel SCR work streams include:

Ofgem will bring the outputs of all the SCR work streams together in Q3 2020, when it intends to make its Full Business Case decision on how and when to proceed with MHHS.

ELEXON chaired the DWG and Ofgem appointed its members. Ofgem was not a member but attended as an observer and provided strategic input where necessary.


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