The First Learnings From Live Market-wide Half-Hourly Settlement Delivery

By Patricia Parker, Principal Consultant, ESG

As Market-wide Half-Hourly Settlement moves through live migration, the industry is gaining a clearer understanding of what it takes to make the new arrangements work in practice.

For much of the Market-wide Half-Hourly Settlement (MHHS) programme, the focus has been on preparation.

Suppliers have invested significant time and effort in technology, testing, qualification and operational planning. Each has been essential to reaching the point where organisations can begin operating under the new settlement arrangements.

Now, live delivery is bringing a different perspective.

At ESG, over 15 of our customers are now live on MHHS, with over 1.7 million supplier MPANs migrated through ESG services. These milestones reflect the commitment of our customers and the teams supporting them. They also provide an opportunity to reflect on what the transition is teaching us.

The wider industry is making substantial progress too. In June 2026, Elexon reported that more than 11.3 million migrations had been completed, with a third of Britain’s electricity metering systems operating under the new arrangements. As of September 2026, over 23.8 million MPANS have migrated, which constitutes just over 70%. The figures demonstrate the scale and pace of the change, and the importance of learning from live experience as migration continues.

It is still early, and every organisation’s experience will be different. But four themes are emerging from our work with customers.

1. MHHS is becoming an operational programme

For much of the programme, progress has been measured through technical milestones.

Systems have been developed and tested. Interfaces have been validated. Qualification and readiness activities have provided the foundations for live delivery.

Those achievements remain essential. But as suppliers move into live operation, attention increasingly turns to how the business works around the technology.

Teams need to manage changing processes, understand their responsibilities and maintain day-to-day operations while migration continues. They also need clear routes for making decisions and resolving issues when circumstances do not follow the expected path.

This is a different kind of readiness. It is less about demonstrating that a system can perform a process and more about ensuring that people and organisations can manage that process consistently in practice.

The early lesson: Technical readiness enables the transition. Operational readiness helps organisations manage it.

2. People need to be as prepared as systems

MHHS changes established ways of working across the electricity market. Even where the technology is ready, people still need time and support to understand what those changes mean for their roles.

That makes training and knowledge-sharing important parts of preparation.

Teams need more than an explanation of new requirements. They need opportunities to explore how processes will work, ask questions and build familiarity with situations they may encounter once live.

The right approach will vary between organisations. Different operating models, systems and responsibilities mean that preparation cannot always follow a single template.

What matters is that people understand not only what is changing, but also how they will work differently and where to turn when they need support.

This preparation does not end at go-live. As teams gain experience, new questions will emerge and understanding will continue to develop.

The early lesson: Preparing people for change is an ongoing part of delivery, not a task to complete before go-live.

3. Live experience creates opportunities to learn

Testing, planning and training can prepare organisations for many scenarios. But live operation provides a different kind of insight.

It shows how systems, processes and people work together under real conditions. It can bring new questions to the surface, reveal where guidance needs to be clearer and highlight opportunities to improve the way teams work.

That experience is valuable beyond the organisation directly involved.

As more suppliers progress through migration, there are opportunities to share relevant learnings, refine approaches and help teams preparing for later stages of delivery.

This does not mean that every supplier will face the same challenges. Each has its own systems, operating model and migration plan. The value lies in using experience to ask better questions, strengthen preparation and respond more effectively as new situations arise.

Collaboration is central to that process. Suppliers, technology providers and industry partners all have a role in communicating clearly and working through issues as the programme progresses.

The early lesson: Live delivery creates knowledge that should inform the next stage of delivery, rather than remain with the teams that experienced it first.

4. Go-live is a milestone, not the end of the journey

Go-live is an important achievement. It represents the culmination of substantial preparation and marks a significant step in a supplier’s transition to MHHS.

But it does not necessarily mean that every MPAN in a supplier’s portfolio has migrated, or that every operational change is complete.

The industry timetable reflects that distinction. Elexon lists 7 May 2027 as the milestone for completing meter migrations, with the move to a shorter settlement timetable scheduled for 2 July 2027. These are connected but separate stages of the wider transition.

For suppliers, this means maintaining focus beyond the initial go-live. Migration activity continues, teams gain experience of new processes and organisations adapt their ways of working over time.

It also means recognising progress without treating any single milestone as proof that MHHS’s longer-term benefits have already been achieved.

The early lesson: Go-live deserves recognition, but sustained support and continued learning are just as important in the stages that follow.

Building on the progress so far

The progress made through MHHS reflects a considerable collective effort across the energy industry.

We want to congratulate our customers who have reached go-live and thank their teams, our ESG colleagues and industry partners for the commitment and collaboration behind each milestone.

The experience gained so far is valuable, but there is still much to learn. As migration continues, organisations will encounter new questions, develop their understanding and identify where further changes may be needed. Some challenges will be addressed within individual businesses; others may require wider industry collaboration.

MHHS is intended to create the conditions for more flexible energy use and new customer propositions, as Ofgem set out when it decided to proceed with the reform. Those are longer-term ambitions, rather than benefits that can be assumed from migration progress alone.

For now, the early lessons are clear: operational readiness matters alongside technical preparation; people need continued support; live experience should inform what comes next; and go-live is one milestone in a longer transition.

As MHHS delivery progresses, so does the industry’s understanding of what it takes to make the new arrangements work in practice.