MHHS Migration Essentials Guide

Market-wide Half Hourly Settlement (MHHS) Migration Wave 0 begins 22nd October 2025 – here’s what you need to know.

The energy industry is undergoing its most significant transformation in decades. And the critical phase of migrating over 30million meters to a new data settlement system starts today.

If you’re a business with an electricity supply, the Market-wide Half Hourly Settlement (MHHS) migration will affect you.

Here’s your essential guide to navigating this change.

What is MHHS Migration?

MHHS migration is the process of moving electricity supplies from the current settlement system to the new MHHS system.

This represents a fundamental shift in how the energy market operates, moving all electricity meters to Half Hourly settlement rather than the mix of Half Hourly and Non-Half Hourly settlement we have today.

In practical terms, this means transitioning all electricity supplies – and the data associated with them – from legacy systems to a modern, more accurate settlement framework.

How does the migration work?

The migration process centres on the Supplier, Data and Meter agents.

During migration, existing Data & Meter agents will be deappointed from the old system and reappointed to the new MHHS system.

This isn’t a simple switch-over.

It’s a carefully orchestrated process with new systems which have been tested and qualified ahead of the migration phase.

Suppliers and their Agents will coordinate this transition.

When is MHHS migration happening?

Migration is already underway.

Wave 0 launched on Wednesday 22nd October 2025, marking the beginning of a phased rollout that will continue until May 2027.

The programme of migration is happening in waves – with each Supplier sitting in a specific wave.

This ensures stability and allow the industry time to manage the complexity of migrating millions of supply points without disruption to businesses or consumers.

Who is affected by MHHS Migration?

Everyone with an electricity supply will be affected by the MHHS migration. This includes:

• Businesses of all sizes – from small enterprises to large industrial operations
• Domestic residences – all households will also move
• Suppliers managing customer portfolios
• Operations, Procurement & Sustainability teams that rely on metering data for billing, forecasting and compliance
• Data & Metering service providers facilitating the technical transition

What electricity supplies are migrating to MHHS?

All electricity supplies are migrating under MHHS, both metered AND unmetered.

• Unmetered supplies – will migrate into an Unmetered Supply Data Service provider
• Advanced/AMR metered supplies – meters capable of HH settlement will be migrated to the new MHHS system, with Data collected by chosen agents, like Stark
• SMETS/Smart metered supplies – these meters will migrate into MHHS and have data collected centrally by the Data Communications Company (DCC)
• Traditional/Dumb metered supplies – will need the meter replaced with one capable of remote data collection and HH settlement

When will my supplies migrate?

Migration is happening in Waves, with different suppliers scheduled for different periods. Your migration timing depends on which Supplier manages your electricity account.

To find out when a Supplier is migrating, visit the MHHS Programme’s Central Register

This central register is regularly updated, showing which wave each supplier is assigned to, and helps you plan accordingly.

Do I need to do anything to enable migration?

No, it will be handled by your Supplier, Data and Metering agents. However you should be aware of whether your metering estate is MHHS-ready.

Preparing your metering estate ahead of migration

One of the most critical factors for successful migration is ensuring your metering estate is ready.

For businesses, this means acting now, well ahead of your scheduled migration wave.

If your metering estate is not MHHS-ready, then you risk increased costs and estimated bills.

Your meters need to be capable of Half Hourly settlement with remote data collection.

• If you’re still operating Traditional/Dumb meters, these will need to be upgraded or replaced before migration can proceed.
• If your data relies on manual meter reads, then you need to challenge this, as MHHS’s strict data targets will mean manual reads increase, and so will the costs.

There are not just technical requirements – they’re essential to avoid disruption to your energy supply and billing, and to avoid unnecessary costs.

What should you do now?

For businesses:

• Check when your supplier is migrating using the links above
• Conduct a full audit of your metering estate – identifying traditional, Advanced, Smart, & Unmetered supplies
• Speak to your supplier or Stark about MHHS migration readiness
• Ensure your contact details are up to date with your Metering agent

For suppliers and operations teams:

• Review your wave assignment and migration timeline
• Ensure your agents are MHHS-qualified
• Communicate proactively with Agents and customers about their migration dates and any meter requirements

The Bigger Picture

MHHS migration isn’t just an administrative exercise.

It’s laying the foundation for a smarter, more flexible energy system that will enable better pricing, improve grid management, and support the UK’s Net Zero ambitions.

By moving to Half Hourly settlement, the industry can reward flexible demand, integrate renewable energy more effectively, and give businesses better visibility of their energy consumption.

The journey begins now.

Stay on top of the MHHS migration by signing up to our mailing list, registering for our Report and preparing your metering estate for the transition to MHHS.