Our MHHS FAQ

In a nutshell, the aim of MHHS is to gain more timely insight into how much electricity is being used by consumers, and when, so that generators, suppliers and consumers can better understand, forecast and generate the volume of power the UK needs.

According to industry regulator Ofgem, this will then unlock "flexibility to support the transition to Net Zero" and " contribute to a more cost-effective electricity system, encouraging more flexible use of energy and helping consumers lower their bills."

Settlement is the term given to reconciling the difference between the volume of electricity a supplier has 'contractually' purchased and the actual volume used by it's customers.

In a major way. MHHS will change a large number of industry processes related to industry settlement (see previous question) by introducing a totally new operating model. This new model will segment the electricity market by meter type, with new meter segments replacing existing ones as follows:

There will also be new metering services (see Meter Operators and Data Collectors question).

The timescale for industry to deliver MHHS starts in April 2025 and runs through 2026. All industry parties will operate to different timelines within this period, as determined and co-ordinated by the overarching MHHS programme overseen by Ofgem.

Suppliers will need to adapt to new MHHS requirements and processes, and undertake qualification processes to demonstrate their ability to continue supplying electricity to consumers. For example, by putting in place system architecture to handle new and much larger quantities of data, along with updated business processes and working with the new meter agent roles.

For consumers, this will depend on the types of meter you have and the services you currently receive. There is no 'one size fits all' experience. Most changes will be behind the scenes. But you may be asked to confirm information regarding your meters and supply points to ensure accuracy, or to liaise with your Meter Operator or supplier where a meter is not working or data collection is impeded. Suppliers and Meter Operators are currently assessing the most effective workflows and should communicate with customers directly.

Yes, the MHHS programme has it's own website and there is a glossary you can download from the Help Centre section.

The commercial impact of MHHS is being assessed however we are not aware of any changes in the gas sector. If this changes, or if another programme is initiated, we will be in touch and will keep all affected customers up to date.

The qualification phase of the MHHS programme has been designed to make sure that we, and all other suppliers intending to operate in the post-MHHS world have the right systems, processes and controls in place to undertake the Balancing & Settlement Code (BSC) and Retail Energy Code (REC) requirements.

We're happy to confirm that we're preparing to qualify in the Advanced Data and Metering Services roles:

• Advanced Data Service (ADS) - ADS is the service that retrieves and processes Settlement Period Level data (the consumption or export meter data) from Advanced Meters that are in the Advanced Market Segment. This could be either actual Half-Hourly data, data calculated between multiple readings, or in the case of Unmetered Supplies (UMS), data calculated from the Settlement Period.
• The Metering Service (Advanced) (MSA) - MSA is the service that will be responsible for the installation and maintenance of meters in the Advanced Market Segment. 

Qualification will occur in two windows for us.

1. Advanced Data and Metering Services are scheduled for the first migration window. currently scheduled to start in 2025.
2. The Supplier qualification window will come later in the programme and when we have more information, we'll be in touch.

No - our team of experts are working hard to ensure that our systems will be able to continue to operate before as well as after the MHHS programme is complete. 

The timing of the migration is still uncertain as we are finalising our migration plans. Please rest assured, we will reach out to all our customers ahead of any changes.

The timing for your metering and supply renewal is not directly tied to MHHS. It will depend on when your contract is up for renewal and the specific terms and conditions associated with it.

Each supplier may have their own unique approach to this situation. Rest assured, if we are your chosen supplier, we will reach out to you as soon as more information becomes available.

Metering will continue to be a cost as it is today and there may be a cost for a data visualisation tool (depending on if you choose to use one, which one you choose and your level of access).

All meter types will be re-classified into three new segments replacing the current Half-Hourly or Non-Half Hourly split as detailed in the 'How will MHHS impact the electricity industry?' question.

It is not envisaged that meter exchanges will be needed to facilitate MHHS. However, in some circumstances, we may need to conduct site visits and potentially exchange some meters. But we will communicate with you if this is the case.

If you would like to arrange a meter exchange to either a Smart or AMR meter, please get in touch to arrange a free meter exchange

The Smart meter rollout, which began in 2011, represented the start of the move to gain greater insight into nearer real-time electricity consumption.
The aim is to have timely data from every meter in the UK to track and understand electricity consumption, again to support better planning for generation. Smart meter data will therefore support MHHS data visibility.

Our migration schedule will be dependent on several factors, such as how many MPANs we are allowed to migrate in a day or the type of meter to be migrated. When the time is right, we will get in touch with our customers to make sure they are kept up-to-date and as this change will mean all meters will be migrated regardless of type, we will include a list of all the affected meters when appropriate.

If you do not have a Smart or AMR meter and we continue to supply you using a traditional meter, we will continue to use readings from yourself or agents working on our behalf, to ensure you continue to receive an accurate invoice.

If you would like to arrange a meter exchange to either a Smart or AMR meter, please get in touch to arrange an exchange by visiting us here.

All meters will be migrated as part of the industry-wide MHHS programme, but we don’t currently believe this will involve a physical meter exchange, however your meters may end up in different segments:

1. HH and AMR meters will fall under the Advanced segment, requiring an ADS and MSA appointment.
2. Smart meters will need an SDS and MSS appointment.

Please note that charges may vary across these segments based on the selected agents.

This is similar to how the UK energy industry works today. If demand is completely unpredictable then you may not be able to take advantage of certain time-of-use products.

Both the import and export suppliers will be responsible as they are registered to each respective MPAN. Both suppliers will also need to ensure the meter has the same Meter Services Agent and Advanced Data Service Agent appointed. For more information, you will need to contact each supplier for further information.

If you currently have a Non-Half-Hourly (NHH) meter or if your Half-Hourly (HH) meter is outside of signal range, your data and usage will continue to be read monthly or quarterly by agents working on our behalf.

Your meter will still be migrated as part of MHHS.

MHHS will not change how existing Non-Half-Hourly (NHH) meters are configured. These will continue to be done over the air or by a physical site visit by a Metering Service (Advanced) agent using appropriate software for the meter, via instruction from both the import and export supplier(s).

The Topline descriptors are currently scheduled for change in March 2025, with numbers changing at the point of migration.

The new top-line information will be reflected on the first bill after the migration completion.

As part of the wider MHHS changes the top line will be amended as:

• “Standard Settlement Configuration ID” will replace “Meter Timeswitch code (MTC)”
• “DUoS Tariff ID” instead of “Line Loss Factor configuration (LLFC)”

After the MHHS migration is complete, Profile Classes will no longer be used. The only exceptions to this are Profile Classes 02 and 04, which will continue to be used to identify Economy 7 and 10 meters.

Yes, the revised topline will be updated on ECOES after the migration has been completed.

Once the MHHS migration is complete, there may be a brief period where contracts still mention the old industry descriptors. Don't worry, we will keep our customers informed about this and any potential impacts as we approach the migration window.

As part of the MHHS programme, MOPs and DCs will undergo a name change - MOP will be referred to as Metering Service (Advanced or Smart), and DC as Data Service (Advanced or Smart) moving forward. The specific details will be determined by the agent you have a contract with and their post-MHHS roles. We will be in touch with our Metering customers to talk through any changes to contracts ahead of time to make sure everything is a clear and understandable as possible.

All meters have a MOP and DC appointed today. These charges may be applied directly or through the standing charge. In the future, more meters may have their metering charges applied directly, but it is not yet clear if this will result in the same, higher, or lower costs. Rest assured, we will communicate with our customers closer to their migration to explain the potential impacts of this transition.

If you have already partnered with third-party metering agents (MSS/MSA or SDS/ADS) independently, and we're your supplier, please let us know so we can work with them.

If you haven't chosen any agents yet, we will appoint agents on your behalf, although they may not be your preferred choice. It's important to communicate your preferences so we can ensure the contracts meet both your needs and ours.

Yes, suppliers will appoint metering agents if the customer hasn't specified an agent.

There will be major changes to existing metering services, with new roles to reflect the new services needed to deliver MHHS. The table below broadly sets what will change:

Like suppliers, metering service providers will also need to adapt and qualify to become accredited in the new roles.

P434 is an industry-wide modification which requires all Non-Half-Hourly (NHH) Unmetered (UMS) Supplies to be Half-Hourly (HH) settled on a single primary MPAN (Meter Point Administration Number) by 31 March 2025 so that there are no more NHH UMS MPANs by 1 April 2025.

P434 will enable UMS sites to be included in the Market-wide Half-Hourly Settlement (MHHS) migration which will happen shortly after.

Market-wide Half-Hourly Settlement (MHHS) is set to revolutionise the energy sector by implementing ground-breaking changes in how we produce, consume and engage with electricity, all with the goal of benefiting everyone involved. For more information about MHHS, click here.

No - your account number will not change as part of the P434 process.

There are no planned changes to bill cycles so this should remain as monthly, quarterly or annually.

If you had multiple MPANs before the Change of Measurement class (CoMC) process, you may see a reduction in the number of invoices you receive, depending on whether you received separate invoices per MPAN previously.

If you only have one primary MPAN assigned to your inventory, this will be the one converted to HH.

If you have multiple MPANs across your inventory, these will be moved to a single (primary) MPAN which will then be put through the Change of Measurement class (CoMC) process and moved to HH settlement.

If you have multiple inventories, for example across multiple sites, you may have multiple primary MPANs.

You will need to discuss this with your Unmetered Supplies System Operator (UMSO).

Suppliers and UMSOs have been working together so that the UMSO can get in touch with you and make sure that the necessary changes to your inventory can be agreed.

If this has not happened we would encourage you to contact your UMSO directly.

If you are currently have two or more MPANs across your UMS inventory, then all of the assets will be moved to a single primary MPAN.

We will then complete a CoMC process which will move the single (primary) MPAN to HH settlement. At this point, any redundant MPANs no longer in use will be terminated by your DNO (Distribution Network Operator).

If you have multiple inventories, for example across multiple sites, you may have multiple primary MPANs.

After your primary NHH UMS MPAN has been migrated as part of P434, your Half-Hourly consumption will be calculated by a Meter Administrator (MA) on a single MPAN.

This calculation will include all of your usage across your UMS inventory so your charges will reflect the usage all year round and take into account any seasonal load.