Market-wide Half-Hourly Settlement (MHHS) Migration
A short guide for SmartestEnergy customers
The guide includes: • An overview of what MHHS migration means • What customers can expect before, during and after migration • Frequently asked questions and common myths answered
Thank you for reading our
MHHS Guide
This guide explains what MHHS migration means for you, what to expect, and reassures you there’s no impact to your supply, contract or day‑to‑day operations.
First published: July 2026
What is migration?
What happens and the Change of Agent process
How market roles change under MHHS
An update to roles and a new platform
What customers should expect
Before, during and after migration
Preparing for MHHS migration
How to ensure a smooth transition
Migration timeline
Key dates to note
FAQs and Myths
Your questions answered
Migration is the industry-wide process that moves electricity customers from the current settlement arrangements onto the new Market-wide Half-Hourly Settlement (MHHS) framework.
Migration changes how electricity usage data is collected, processed and settled across the market. It does not change who supplies your energy, your contract with SmartestEnergy, or how your site is physically supplied with electricity.
Migration is coordinated by your supplier and supported by new MHHS systems. It involves SmartestEnergy, meter and data service providers, and new market systems, and will be delivered in phases, with customers moved in groups to minimise disruption and ensure accurate data migration.
The first 10% of MPANs migrated must meet a set of criteria dictated by industry to evidence our ability to migrate different types of MPANs and customers
Migration sequencing will be determined by the migration readiness of the customer's portfolio
We will attempt to migrate all MPANs of a customer together in one go (but this may not be possible)
New Data Integration Platform (DIP)
Changes to Data Transfer Network (DTN)
Changes to ECOES
Changes to Central Switching Service (CSS)
As part of migration, each site will go through the standard industry Change of Agent process.
Your existing meter and data agents will be de-appointed
New MHHS-compliant service providers will be appointed on your behalf; where you have a direct agreement for the new services we will appoint your contracted provider.
Your MPANs are then managed through new MHHS systems and processes
This is a technical market process, not a commercial change.
Importantly:
Your SmartestEnergy contract does not change
You are not required to appoint anyone yourself
Your electricity supply is not interrupted.
The ones that look after meters
Previous market roles
Market roles in an MHHS world
The ones who retrieve and process meter data
The ones who analyse energy data
A new central platform (Data Integration Platform) securely shares half‑hourly data across the market, improving accuracy and consistency while reducing duplication.
We’ll let you know early in advance when your site is scheduled to migrate. We may carry out data or metering readiness checks and in most cases, no action is required from you. We will be in touch early with those who are required to do something.
Migration takes place within a scheduled window, with your supply continuing as normal and no disruption to service.
Your site will operate fully under MHHS arrangements, with settlement based on standardised half‑hourly data.
For SMART and AMR meters, billing will use more accurate half‑hourly data, while most system and process changes remain behind the scenes.
In most cases, no action is required. SmartestEnergy manages the migration on your behalf and will contact you in advance if any action is needed.
To help ensure a smooth migration, customers should:
Ensure smart meters are functioning correctly and contact details are up to date, particularly where there are known meter issues.
Work with us to support any planned or in‑progress meter exchanges, including providing access where required.
Provide meter readings or photographs if requested, where access cannot be gained.
Be aware that some non-half-hourly meters may need to be upgraded as part of the move to half-hourly settlement.
Let us know if any sites are subject to:
a change of tenancy
are long‑term vacant
have a disconnection in progress or planned.
Qualification
Migration
Go-live
Sites are grouped into migration slots
Readiness checks are completed in advance
If any issues are identified, migration may be rescheduled to ensure accuracy and stability.
When will my meters be migrated to MHHS?
Will there be any disruption, site visits or downtime during migration?
SmartestEnergy’s migration window runs from October 2026 to May 2027. All electricity MPANs – both half‑hourly and non‑half‑hourly – will be migrated during this period.While we cannot guarantee that all of your sites will migrate on the same day, we aim to migrate all of your sites within the same migration block, where possible. You will be notified in advance, and your Account Manager will support you through the process.
In most cases, no. Migration is primarily a system and data change and does not require site access or cause supply interruption. If a particular site does need a meter exchange or visit, we will contact you well in advance to agree the next steps.
Will my bills, contract rates or charges change when migration happens?
Your existing contract, rates and billing terms are fully honoured through the migration process. MHHS does not introduce pricing changes or new charges mid‑contract. Any future changes to tariffs or products would only apply at renewal.
If you have a SMART or AMR meter, you may notice some changes to the format of your bill, as it will reflect the half-hourly (HH) data made available through MHHS but all changes will be fully communicated ahead of the change so you will be aware of what to expect.
What happens if any of my sites fail to migrate?
Why could my sites fail to migrate?
If we are unable to resolve the issue ourselves, we will promptly communicate the problem to you and any other relevant parties to ensure all sites are successfully migrated.
Your site(s)/MPAN(s) may fail to migrate for a small number of reasons, such as missing or mismatched data within industry systems.
If this happens, SmartestEnergy will review the issue on a case‑by‑case basis. In most instances, we expect to be able to resolve migration issues ourselves or with service providers. Where your support is needed, we’ll contact you directly and guide you through any required steps.
What is the difference between agents and service providers under MHHS?
Currently, what we refer to as agents is changing to service providers. Under MHHS, service providers is the term used to describe the organisations that carry out activities on your supply, such as metering, data collection and data processing.
For customers, there is no fundamental change in what these organisations do - their responsibilities remain largely the same. You should not notice any day-to-day impact, and you do not need to interact with service providers any differently as a result of MHHS.
Migration means I’ll automatically move to a half‑hourly tariff.
If I’m already half-hourly, migration doesn’t apply to me.
Migration to half‑hourly settlement does not mean a move to a half‑hourly tariff. Your current tariff structure (e.g. single‑rate, day/night) stays exactly the same during your contract. New tariff options, if offered, would only be available at renewal.
Even customers who are already settled half-hourly will still be migrated. Existing half-hourly sites move onto new MHHS service providers, new customer segments and updated settlement timelines. This does not affect supply, pricing or contracts, but it is still a required market change.
Migration could result in unexpected capacity charges.
Migration itself does not introduce capacity charges. Capacity charges depend on whether a site has a Maximum Import Capacity (MIC) and the applicable DNO tariff. MHHS migration does not automatically add capacity charging or change your network tariff.
My business can opt out of, or delay, migration.
MHHS migration is a mandatory, industry‑wide change. Customers cannot opt out or delay migration. We will manage the transition carefully to ensure minimal customer impact and clear communication.
