Market-wide Half Hourly Settlement (MHHS) Working Groups

In July 2017, Ofgem launched its Significant Code Review (SCR) on Electricity Settlement Reform.

Here you can find the outputs of three industry working groups which Elexon is chairing and providing with technical leadership to support Ofgem’s SCR. All three groups report to Ofgem. Ofgem sets their 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 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 further the outstanding detailed areas of the DWG’s TOM design. 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 solution architecture required to enable the DWG’s TOM. This solution architecture will set the framework for subsequent IT system design.

Due to a variety of factors including COVID-19, we are currently re-planning the CCDG’s and AWG’s activities with Ofgem. We will publish updated work plans for the groups as soon as possible. The diagram below is our latest view of the key milestones and their sequencing / timings.

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 draft Impact Assessment consultation, on which Ofgem seeks responses by 14 September 2020)

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.


Click on the X next to any of the icons to replace them with a short-cut link to the page you are currently on or search for a specific page.

List of Insights


BSC training services

Market Entry

Charge Codes and Switch Regimes

Add New