What is Market-wide Half-Hourly Settlement (MHHS)?
A simple guide to what’s changing and why it matters.
The way the UK electricity system operates is evolving, as the energy industry works towards a cleaner and more flexible future. Market-wide Half-Hourly Settlement (MHHS) is part of that shift, changing how energy usage is measured and managed across the grid.
While this won’t change your day-to-day energy supply or interrupt your service, it’s good news for customers, and an important step towards a lower-carbon energy system.
Read this guide to understand what MHHS is, why it’s being introduced, and how it will support a smarter energy system.
What is the MHHS programme?
Market-wide Half-Hourly Settlement (MHHS) is a change to how electricity use is measured across the UK. The industry reform is led by the energy regulator Ofgem to modernise the electricity industry and its processes.
Instead of relying on broader estimates, electricity usage will be recorded in 30-minute intervals. This will enable energy suppliers to power homes and businesses with renewable electricity more efficiently.
To put it simply, it’s a bit like a supermarket understanding when customers shop, rather than just how much is sold by the end of the day. That makes it easier to stock shelves at the right times, reduce waste, and make better use of what’s available. MHHS brings that same level of visibility to the energy system, helping ensure electricity is generated and used when it’s needed most.
Why is MHHS being introduced?
With the grid getting greener every year, the way electricity is managed is being updated to keep pace – as the old system wasn’t designed for a world powered by renewables. The way electricity was measured, and how frequently suppliers received that data, is one such example.
In many cases, suppliers still rely on older methods that show how much electricity has been used overall, but not exactly when it was used. By using half-hourly data instead, suppliers can:
- Predict demand more accurately, helping to reduce reliance on fossil fuel energy
- Improve the accuracy of billing and energy forecasting for customers
- Give customers better visibility of their energy use and trends
- Offer smarter time of use tariffs which help customers lower their energy bills by shifting how and when they use energy
This is particularly important as more homes adopt low-carbon technology and more renewable electricity projects are developed.
What does MHHS mean for customers?
For most customers, this change will happen in the background, meaning:
- No action is required
- Your electricity supply will not change or be interrupted
- You will see no difference in your electricity at home
In time, MHHS will enable smarter, more flexible tariff offerings which can help customers better manage their energy use and reduce their bills.
If there is ever anything specific you need to know about your account or meter, we will contact you directly.
When is MHHS happening?
MHHS is being rolled out across the energy industry in stages. It went live in September 2025, some suppliers have already started migrating customers, and completion is currently aimed for May 2027.
Good Energy will begin migrating customers from October 2026.
What are the benefits of MHHS?
Reduced reliance on fossil fuels
A more accurate and flexible electricity system can make better use of renewable electricity.
More accurate billing
MHHS helps improve billing accuracy, because it gives a clearer picture of when electricity is being used.
Smarter products and tariffs
MHHS supports flexible time of use tariffs that reward you with lower rates for using energy when demand is lower.
Better energy insights
Half-hourly data can give customers better insight into their electricity usage patterns.
How does this relate to smart meters?
Smart meters can record electricity usage in more detail, including in half-hour periods.
As MHHS rolls out, smart meters will play an increasingly important role in helping customers access the full benefits of a more flexible energy market, including time of use tariffs.
They can also help customers better understand their own energy use, making it easier to spot patterns and take more control over usage.
If you’d like to access these future products that could save you money, and you don’t currently have a smart meter – you can contact us here to arrange an appointment to have one installed.
As a renewable energy pioneer for over 25 years, we’ve long championed a smarter, more flexible grid that can make the most of clean power. MHHS is an important step in that direction, as it helps modernise the electricity system and supports the transition to cleaner energy.
Learn more about smart meters
Why get a smart meter
By getting a smart meter, you can join millions of homes that are fighting climate change by making Britain’s whole energy system greener. Read this blog to find out how smart meters save energy and how to get one.
Learn about smart meters
Smart meters run on a tiny amount of electricity, but the information they provide could help you save much more than that by having more control over your energy. From how smart meters save energy to smart meter data security, get all your questions answered.
What happens during smart meter installation?
Good Energy has partnered with specialist smart meter installers, SMS. Find out all you need to know about booking your smart meter installation and what happens on the day.
Commonly asked questions about MHHS
MHHS stands for Market-wide Half-Hourly Settlement. The programme will change how electricity use is measured, using data every 30 minutes instead of broader estimates.
Settlement is the process the energy industry uses to match the electricity suppliers buy with the electricity customers actually use, so costs can be worked out accurately.
MHHS is being introduced to help create a smarter, more flexible energy system that can better support the distribution of renewable electricity when demand is highest.
No, customers do not need to do anything for MHHS. This is an industry-wide change happening behind the scenes.
No, MHHS will not affect your electricity supply.
MHHS is being rolled out across the energy industry in stages. It went live in September 2025, with customer migrations now underway.
Good Energy will begin migrating customers from October 2026, with completion currently aimed for April 2027.
MHHS will not directly change how you are billed, but it may help improve billing accuracy over time.
MHHS does not require a smart meter, but smart meters do help provide the detailed data that supports the new system.
MHHS supports renewable energy by making it easier to match when people are using energy with times when renewable electricity is available.
Yes, MHHS will help enable smarter tariffs and energy products in the future by giving suppliers more accurate, real-time insight into how and when energy is used.