What Market-wide Half-Hourly Settlement (MHHS) Means for Businesses

The energy landscape is set to undergo significant change in 2025 with the rollout of Market-wide Half-Hourly Settlement (MHHS), a national initiative led by Ofgem. Linda Spencer, MD of Professional Energy People, explains how businesses can prepare now to maximise the benefits of this transformation.

What Is MHHS?

MHHS will impact all businesses on non-half-hourly (NHH) meters in the UK, changing how electricity usage is measured, settled, and billed. From October 2025, changes will roll out across the industry, with all relevant customers transitioned to MHHS by May 2027. While much of the transition will happen behind the scenes, businesses will notice changes in settlement, billing, and available services.

What Businesses Need to Know

1. Moving to Half-Hourly (HH) Settlement

• All Meter Point Administration Numbers (MPANs) will transition to HH settlement, which provides a detailed, real-time picture of energy use.

• For others, HH settlement means more accurate billing and potential updates to contracts and costs.

• Businesses already using HH meters will see no changes.

2. New Industry Terminology and Market Segments

• The MHHS program introduces new categories for MPANs: Smart, Advanced, or Unmetered.

• Existing NHH processes will be replaced with updated services and data management tools.

3. Staggered Supplier Rollout & Reverse Migration

As MHHS rolls out, suppliers will become qualified at different points over an 18-month window starting October 2025. This raises a common question: what happens if you switch suppliers mid-transition?

To keep the market open and minimise disruption, reverse migration will be possible. If you move from a qualified supplier (on MHHS) to one that isn’t yet qualified, your MPAN can temporarily revert to the legacy system. Once the new supplier becomes MHHS-ready, your account will migrate back.

This interim measure, confirmed by Elexon (the settlement body that will govern MHHS) will only be available between October 2025 and October 2026 and ensures continuous support during supplier switches.

Potential Benefits of MHHS

Ofgem estimates MHHS could deliver £1.5–4.5 billion in net benefits by 2045. For businesses, this presents opportunities to enhance efficiency and reduce costs.

Having smart metering in place is critical for accessing future opportunities in areas like flexible tariffs, EV charging, and battery storage.

Key Benefits Include:

• Smarter Energy Insights: Access accurate HH data to better understand and manage energy usage, predict demand, and plan for future needs.

• Cost-Saving Opportunities: Unlock new products and time-of-use tariffs, supporting the transition to Net Zero and reducing energy bills.

• Simplified Processes: Avoid the hassle of manual meter data downloads by upgrading legacy meters to smart or advanced options.

Potential Cost Implications

There may be extra charges incurred for new half-hourly meters owing to the migration. This will be determined by each individual energy supplier. This is their current feedback:

Corona

As you may be aware, over the next few years, the energy market will switch to a system that settles electricity based on half-hourly data for all domestic and non-domestic meters. Suppliers will start migrating meters, like yours, from 01/11/2025. If you are in an agreed fixed contract at migration point, your rates shouldn’t change but if there are additional charges, these will be passed on to you by the supplier.

SSE

If SSE Protect, no additional charges will incur until the current contract expires.

British Gas

Non micro customers which have signed through enterprise will be required to recontract. If the customer is micro, the agreed prices will be used up until the end of the contract.

Marble Power

No decision made yet.

SEFE

If a customer is migrated during their NHH contract, a new HH contract will have to be agreed.

Total Energies

They will attempt to honour all rates but if there is a significant increase to the costs they incur these may be passed through.

EDF

If migrated meter is settled under a 05-08 profile and therefore does not have an allocated kVA, there will be no need to re-sign contracts. Any other profiles may have charges passed through or have to re-sign a new contract.

Smartest Energy

They will honour all contracts until contract end date.

Dyce Energy

They will attempt to honour existing contracts but there’s no guarantee that some charges may be passed through.

Last updated 23 July 2025. Updates will be made as new information becomes available.

We’re Here to Help

Your supplier will guide you through the mandatory transition to MHHS. Professional Energy People’s in-house experts are also here to support you with advice and services tailored to your business needs.

For energy procurement advice view our website or contact us today.

0330 0022180 | info@pepgb.com