Market-wide half hourly settlement: Vital to making new energy work

In November of last year, Ofgem took the decision to delay key milestones in the rollout of the Market-Wide Half Hourly Settlement (MHHS) by 6.5 months, pushing back the full transition to half-hourly settlement by at least that amount of time overall. 

Under the previous plan, migration for early MHHS adopters was set to begin in April 2025 and take 18 months, but with these delays the rollout is now not scheduled to begin until October 2025, and not expected to finish until July 2027. 

Ofgem have explained that the delay is intended to give more opportunity to test the new system, and as a leading supplier that deals every day with the complexities of the UK's energy grid, we understand the need to be thorough. 

However, as the country pushes forward with the energy transition, and the Government works towards its Clean Power 2030 Action Plan, it’s becoming more and more important that there are no further delays to the rollout. That’s because MHHS will help us deliver one of the essential components of making new energy work: flexibility. 

The importance of flexibility in making new energy work 

There were roughly 38 million smart meters installed in UK households at the end of 2024, each with the potential to share meter readings with suppliers on a half-hourly basis. That half-hourly capability is essential to making the most of the UK’s renewable generation capacity. 

Unlike with fossil fuels, we can’t decide when we want to get electricity from resources like the sun and wind, because they are dependent on factors like weather and time of day. This means that at some times we are likely not to have enough renewable electricity available to meet demand, and at others are likely to have too much. 

Through a combination of battery storage and adapting the way consumers use electricity we can overcome that challenge by building more flexibility into the energy system, but this second part requires data. 

If we want customers to use energy more flexibly, we need to make it worth their while. At E.ON, we’re already working to do this with products like the Next Smart Saver tariff, which offers peak, off-peak, and super off-peak rates to empower customers to save money at certain times of day. 

Half-hourly consumption data would allow us to go even further, introducing a whole new generation of super-flexible tariffs to help customers take control of their bills, and support the grid by balancing out supply and demand. In fact, Ofgem estimated in 2021 that MHHS could save consumers between £1.6 and £4.5 billion by 2045. 

We’re ready to make the most of customers’ half-hourly data to bring them the best tariffs possible, and we know that the Government and Ofgem are keen to see this happen, and to see more flexibility in the UK’s energy system. 

That’s why it’s so important that there are no further delays to the rollout of MHHS . MHHS is not merely a technical upgrade, it’s a crucial step to unlocking the flexibility needed to reach Clean Power 2030, help customers take control of their bills, and make new energy work.