MHHS Design Working Group (ceased)

The Elexon-led DWG designed the Target Operating Model (TOM) for Market-wide Half Hourly Settlement (MHHS), as well as the high-level 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.

This Working Group has ceased. The content on this page is for archive reference only. Further information about from the following web pages:

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 is continuing to gather information and feedback before publishing its final decisions.

Following Ofgem’s preliminary decision, the DWG is closed down. On behalf of the DWG, we thank everyone who inputted to its work. You can still find the group’s key outputs under ‘Related Content’. You can also view papers for individual DWG meetings under ‘Meetings’.

Further TOM development work is now being undertaken by two separate industry working groups, both chaired by Elexon under SCR governance. These are the:

You can find more information here about how all three groups fit into Ofgem’s wider SCR.

About the DWG’s work

The DWG 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.

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.

The DWG consulted on its report from 18 February 2019 to 15 March 2019. 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. 

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. Read the DWG’s final report.

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.

Associated documentation


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