Market Wide Half Hourly Settlement (MHHS)

Market Wide Half Hourly Settlement (MHHS) is a major industry to transform the way the electricity market operates. Under MHHS, all electricity customers will have their electricity consumption settled every half hour – something that is currently mandatory for industrial and commercial consumers, but voluntary for all other non-domestic and domestic consumers.

For non-half hourly customers, consumption is settled based on a series of “typical use” classes that make a number of assumptions. The change will lead to a smarter electricity grid that helps the UK to achieve its long-term net zero goals.

MHHS is being introduced because the current model for settling electricity consumption is not suited to the way in which we generate and use electricity today, nor how we expect to generate and use power in the future.

The UK has a target to move to a zero-carbon electricity grid by 2035, and that means that a larger proportion of our electricity is being generated by intermittent renewable sources of generation, such as wind or solar. At the same time, the demand on our electricity grid is increasing due to, amongst other things, greater adoption of electric vehicles and greater use of electricity for heating.

As a result, the typical customer use classes increasingly use various assumptions that do not necessarily reflect how energy is used today. MHHS will modernise this system, allowing suppliers and the grid to settle electricity consumption based on actual consumption data provided by smart and other remotely read meters, and allow suppliers to offer products that encourage customers to avoid high-demand periods.

ENGIE currently working on implementing the required changes that are required by the MHHS Programme, with the aim to complete the transition in October 2026.

ENGIE electricity consumers do not have to do anything to move to MHHS, this transition will be handled by ENGIE. A small number of customers may need to agree a site supply capacity with their Distribution Network Operator after the transition. If you are one of these customers, we will be in contact to explain what you need to do.

MHHS delivers the capability for all suppliers to offer new and innovative tariffs to their customers that reflect the time of day you are using energy based on your actual consumption per half-hour. ENGIE will communicate details of these tariffs to you as they become available.

Under the current system, electricity consumption is accounted for and settled based on half-hourly (HH) and non-half hourly (NHH) settlement and consumption data is collected by NHH and HH Data Collectors.

Under MHHS, this system will change to account for and settle consumption based on metering type or “Market Segment” – Smart, Advanced or Unmetered.  HH consumption data will be collected by Data Services for each segment and provided to electricity suppliers for billing.  If there is no remotely readable Smart or AMR meter in a premises and HH data is therefore not available, the relevant Data Service will estimate HH data using manually collected meter reads and load shapes created by central services.

In cases where there is not a working smart or AMR meter on the premises, the volume settled for each half-hour will be estimated based on data from half-hourly load shaping. Not having a smart or AMR meter may limit your ability to take full advantage of new tariffs that rely on actual half-hourly data to deliver the best savings.

You can apply for a smart meter on our dedicated page.