What is MHHS and Why Does It Matter?
MHHS stands for Market Wide Half-Hourly Settlement. It’s a major change in how electricity is tracked and billed across Great Britain.
Right now, electricity bills are either based on monthly readings (manually read or via your smart meter) or estimated readings. That means your organisation might be paying based on assumptions rather than actual usage. MHHS changes that by measuring electricity use in 30-minute blocks, giving a much clearer picture of when and how energy is used.
This matters because it helps the whole energy system run more efficiently. With better data, energy suppliers can match supply with demand more accurately, reducing waste and making the system more flexible.
Who Will Be Affected?
MHHS will apply to everyone, not just large factories or industrial sites. Whether you’re a small business, a school, or a household, this change will affect how your electricity is billed behind the scenes. Even if your meter doesn’t change physically, the way your energy use is recorded and settled will be updated. This means your bills should become more accurate and reflect your actual usage more closely.
What Will Change?
The key visible change will be the structure of your Supply Number (otherwise known as your Meter Point Administration Number/MPAN) in preparation for MHHS to go live. The Supply Number or S Number for short.. is typically printed on your invoices and itemised on contracts and is unique to each electricity meter.
Currently the Top Line of your S Number is made up of the following items:
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- Profile Class (a two digit number such as 05 or 00)
- Meter Time-Switch Code/MTC (which dictates what tariff you are charged, such as a day rate or day/night rate)
- Line Loss Factor/LLF (typically 3 digits)
Looking forward:
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- The MTC will be replaced by the Standard Settlement Configuration (SSC)
- The LLF will be renamed as the DUoS Tariff ID
The below image visualises the proposed changes so that you can compare the S Number / MPAN on your own electricity invoices.
If you love the detail and wanted to delve further, we recommend visiting the following website https://www.mhhsprogramme.co.uk/.
Why the Change?
As a result of implementing MHHS, it is expected that consumers will receive the following benefits;
- More Accurate Billing
Instead of relying on estimates, bills will be based on actual half-hourly data. This means you’ll pay more precisely for what you use. - Faster Reconciliation
Today, it can take up to a year to fully settle who used what energy and when. MHHS aims to shorten that to just four months, making the system more responsive. - New Roles and Categories
The old way of dividing users into “half-hourly” and “non-half-hourly” will be replaced with new categories like “Smart,” “Advanced,” and “Unmetered.” Behind the scenes, roles like meter operators and data agents will be reorganised to support this new system. - Smarter Tariffs and Incentives
With better data, energy suppliers can offer new types of tariffs. For example, you might be rewarded for using electricity during off-peak times, helping you save money and support a greener grid.
When Is This Happening?
MHHS has been in development for several years. The system officially went live on 22 September 2025, and from late 2025 onwards, meter points (MPANs) will start transitioning to the new system. The full rollout is expected to take around 18 months, with the goal of having all participants on the new system by July 2027.
Why Should Your Organisation Care?
Even if you’re not directly managing energy contracts, MHHS could influence:
- Budgeting and cost control
More accurate bills mean better forecasting and fewer surprises. - Sustainability goals
Smarter energy use supports carbon reduction and environmental targets. - Procurement decisions
New tariffs and incentives could offer better value if you know when and how your organisation uses energy.
Need Help?
We hope this article helped your understanding market wide half hourly settlement scheme, but if you need further help, do let us know by emailing connect@mindfulenergy.co.uk. You can also complete our contact us form.