Market-wide Half-hourly

Settlement (MHHS)

Market-wide half-hourly settlement is one of the most significant reforms the UK electricity market has seen in decades.

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What is MHHS?

MHHS is an OFGEM-led industry reform. This approach will modernise all electricity meters to settle using actual half-hourly consumption data, not assumptions or averages.

The move to Half-Hourly Settlement replaces estimated data with standardised, granular consumption profiles. This modernisation of the UK energy infrastructure is a critical pillar for the energygrid and a more transparent, competitive retail landscape.

Between September 2025 and July 2027, we are working alongside the wider energy sector to transition all meters to Half-Hourly Settlement in strategic stages.

You can read more about MHHS reform here, Elexon.co.uk.

How does MHHS plan to benefit my business?

Under legacy settlement arrangements, faulty or unreadable meters often remained undetected for months, hidden by estimated billing. 

MHHS transitions the UK to a 30-minute settlement cycle, ensuring data gaps and anomalies are identified in near real-time. This granular oversight allows for faster resolution of metering issues, significantly reducing prolonged billing inaccuracies and the reliance on estimated demand profiles.

Half-hourly data provides a high-definition view of electricity usage; this precision enables businesses to make data-driven energy management decisions, identify hidden operational inefficiencies, and align peak activity with lower-cost periods. Accurate, standardised data is the essential foundation for reducing energy waste and optimising commercial overheads.

Frequently Asked Questions

  • It stands for Market-wide Half-Hourly Settlement reform. It’s a mandatory industry-wide change where electricity usage is settled every 30 minutes, providing a more accurate picture of energy demand across the UK.

  • Ofgem-led MHHS energy reform is to modernise the national grid. It makes the system more accurate, efficient, supports the transition to Net Zero, and allows for more innovative, flexible energy tariffs.

  • For most customers, the transition is automatic. We at Unify Energy are managing the migration of your meter data behind the scenes.

  • Not necessarily. If you have a smart or AMR meter, it is already capable of sending half-hourly data. If you have an older "traditional" meter, we may contact you to upgrade to a smart or AMR meter, based on what suits your business best, to ensure you get the full benefits.

  • Your bills will become more accurate as they will be based on regular 30-minute usage, which should ensure more accurate data and fewer estimates. You may also see new tariff options.

  • No, MHHS is a mandatory regulatory reform. However, domestic and small business customers may have choices regarding how their granular data is used for marketing purposes.

  • The industry migration began in late 2025 and is expected to be fully completed by mid-2027.

  • No, if you currently have a working AMR meter, the Market-wide Half-Hourly Settlement is compatible with AMR meters. Only the old meters that are not smart or AMR meters, or the faulty meters, will need changing.

  • As the UK electricity system integrates more variable renewable generation from wind and solar, the grid requires time-specific demand data to maintain stability. MHHS enables the Target Operating Model (TOM) to match national demand precisely with renewable output. By improving system balancing and grid resilience, the reform reduces the carbon intensity of the network and minimises the need for fossil-fuel backup during peak periods.