Market-wide Half Hourly Settlement (MHHS) Working Groups


Here you can find the outputs of three industry working groups which Elexon is chairing and providing with technical leadership to support Ofgem’s Significant Code Review (SCR) on Electricity Settlement Reform.

What MHHS working groups are Elexon leading?

As part of Ofgem’s SCR, Elexon is leading the following three working groups which all report to Ofgem. Ofgem sets the groups’ membership and Terms of Reference.

  • Design Working Group (DWG): The DWG ran from 2017 to 2019 and is now stood down. It designed the Target Operating Model (TOM) for MHHS, as well as the high-level approach for transitioning from the current Settlement arrangements to the TOM. We submitted the DWG’s final report to Ofgem in August 2019. Ofgem gave its preliminary approval to the DWG’s TOM and transition approach in October 2019.
  • Code Change and Development Group (CCDG): The CCDG has been meeting since December 2019. It is developing the DWG’s TOM design and transition approach in more detail. It will also identify, and oversee drafting of, the changes needed to Industry Codes and subsidiary documents to enable the TOM.
  • Architecture Working Group (AWG): The AWG has also been meeting since December 2019. It is developing the reference architecture to enable the TOM. This reference architecture will set the framework for suitable data integration that is appropriate to the new MHHS services.
  • Performance Assurance Working Group: The Performance Assurance Working Group (PAWG) is one of several working groups set up by Elexon to deliver the technical overview of the Market-wide Half Hourly Settlement (MHHS) scope. The focus of the group is to deliver a framework for parties that is appropriate to the new MHHS services.

The diagram below shows the timing of the CCDG’s and AWG’s different consultations and reports. We are currently reviewing the timing of the CCDG’s milestones alongside Ofgem’s wider MHHS Programme planning.

How do these groups fit into Ofgem’s SCR process?

Development of the TOM forms one of several work streams in Ofgem’s wider SCR. Ofgem’s other parallel SCR work streams include:

  • Related policy decisions (on access to Half Hourly data for Settlement purposes and on Supplier Agent functions)
  • Consideration of consumer impacts
  • Development of the business case for MHHS (including Ofgem’s recent Draft Impact Assessment Consultation)

Ofgem will bring the outputs of all the SCR work streams together in its Full Business Case decision on how and when to proceed with MHHS. Ofgem will make the final decision on the TOM and transition approach. The CCDG and AWG can only make recommendations to Ofgem.

Following the CCDG’s final report, Ofgem will also make the necessary changes to licences and Industry Codes, which will not follow the normal Code change processes.


Thank you to everyone who responded to the CCDG’s recent consultation on the detailed TOM design and Code Change Matrices. You can find copies of all the public consultation responses and a summary of the CCDG’s conclusions on the CCDG webpage

The AWG is getting ready to consult on its recommended reference architecture and you can register for our webinar here.


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