Is it time for industry to push back on the Market-wide Half-Hourly settlement?

We have seen a real ramp up in efforts by the industry to ensure both pricing and settlements become better aligned this year through the move towards Market-wide Half Hourly Settlement (MHHS).

The migration that was ordered by Ofgem is more than simply a technology upgrade, though. Rather, it signifies a move towards a more adaptable, responsive, and sustainable energy framework. One that gives customers more control, promotes innovation, and encourages collaboration.

Setting the stage

MHHS sets the stage for a future where achieving net zero is not just a goal, but a tangible reality. This is be applauded. However, the transition has thus far proved far from easy. Much of this has been down to the sheer variety of meters being used up and down the land. Around 30 million need to be updated to be MHHS ready, with 2.6 million of those being within businesses.

As we know, despite smart meters thought to reduce energy consumption by 3.4% for electricity and 3.0% for gas on average, consumers have been reticent to transition to them. In fact, according to the most recent data, 42% of meters in the UK are still not smart. Meaning several million meters need to be ripped and replaced before MHHS can be activated on them.

What is MHHS?

Market-wide Half Hourly Settlement (MHHS) is the new electricity market arrangements that will enable the flexibility to support transition to Net Zero. A shorter and more accurate Settlement timetable using Half Hourly meter readings for settled energy will support a cost-effective electricity system, encourage flexible use of energy, and help lower bills. The MHHS Programme is an industry-led programme established to deliver the Target Operating Model and aims of the Electricity Settlement Reform Significant Code Review (SCR). This will see meters migrate to a new topline to comply with the changes. MPANs will migrate in phases by supplier. The suppliers are going through a qualification process, and this will determine when the MPAN is migrated.

A troubled migration

The fact that the physical meter transition has not yet happened is making the back-end transition of the Top Line Supply Numbers problematic. There are certain older pre-smart meters that simply cannot be transitioned correctly. Yet, time has now run out. September 2025 was the date that Ofgem has ordered many in the industry to be ready to change the Top Line Supply Numbers and migrate meters to be half hourly.

This month the migration programme is scheduled to begin with those suppliers within the first phase needing to migrate their meters to MHHS half hourly billing. Only two of the big six are included in this first phase. This delay will make it impossible for already cash-strapped businesses and residential consumers to be priced with enhanced accuracy based upon true market conditions.

The pressure is on

The fact that there are four distinct phases of transition staggered over a one-year period is putting pressure on all within the downstream supply chain. This is because the meters associated with those energy suppliers participating in the first phase will have to be listed differently and have a markedly different Top Line Supply Number. The Meter Time Switch Code (MTC) will be removed and replaced with a Settlement Configuration (SSC) Id, and the Current Line Loss Factor (LLF) will be split into a DUoS Tariff Id and a new LLF.

It may seem like a minor change, but changing the Top Line Supply Number impacts every system, process or document which holds these numbers, whether that be customer bills or industry databases. And because of the phased approach, all databases will need to be able to process both the old, and new Top Line Supply Numbers. This is causing headaches for the supply chain.

Comparing apples to oranges

Each supplier has needed to interpret how to get the Ofgem mandates to work for them. The reality is that each supplier has different technical expertise. It is an unfortunate truth that the energy industry is one that is often shackled by the past and has found it difficult to digitally transformed as much as others. Because of this, each supplier has wildly different technology stacks and different billing platforms. Now, they are being asked to use different field lengths within the databases to be able to process both the old and new top lines during the transition. This is tantamount to comparing apples to oranges.

Of course, this is unfairly hampering the less technologically adept suppliers. Because they are unable to input the new Top Line Supply Numbers, they are unable to take on that meter. This is leading to an unfair playing field.

Multiple hurdles

The whole point of the move towards MHHS was for consumers to get the best and most appropriate rates. It was feted as something that would boost accuracy and stability. Something that would allow consumers to make more informed decisions about when and how they use their energy. 

Yet, the industry was clearly unprepared.

The transition is placing multiple hurdles in front of those within the downstream supply chain. The reality is that until the migration of all the suppliers happens in 2027, consumers will simply not be getting the best deals.

The move to MHHS was always going to include a teething period where we would all need to become familiar with the required changes to the meters and the associated new terminologies. Yet, with the earliest that time of use tariffs will come in being another two years, maybe it is time to push back.