Contents
On this page you can find a full set of readiness checklists for Market-wide Half Hourly Settlement, covering all Electricity Market Participants.
Some changes require participants to have changes implemented for MHHS Go-Live at MHHS Programme Milestones 8 and 10 in September 2025.
Other changes are not required until a REC Party is MHHS Qualified.
These checklists are for guidance only. Market Participants are responsible for ensuring their own readiness through review of the approved MHHS design artefacts, and any subsequent changes agreed through MHHS Change Control.
Checklists: |
All Market Participants
M10 (MHHS go-live) Checklist
All Market Participants, regardless of when they qualify for MHHS, must ensure they are ready for these changes at MHHS Go-Live (M10):
- Change to the approach to maintaining SSC and TPR valid set. This will no longer be specific to individual DNO networks for MHHS Metering Points
- Transfer of responsibility for maintaining SSC and TPR domain data from BSC to REC.
- New process for requesting changes to the ‘Meter Configuration Tables’ established under the REC - further information
- The existing valid set will be frozen until all Metering Points are migrated at M15
- Changes to Data Items:
- J0007 'Requested Action Code'
- J2255 ‘MPAS D0304 Response Code’
- J2256 ‘MOP Flow Response Code’
- J0171 ‘Reading Type’
- Additional Scenario Variants to reflect the new Market Roles - Market Participants required to establish DTN routing to enable exchange of data with new Market Roles
- Changes to Data Items available via the Electricity Enquiry Service (EES) - includes changes to the EES API technical specification impacting all API users
- Update to Agent Appointment and Switch processes to recognise MHHS Migration e.g. Forward Migration as the Losing Supplier / Agent and Reverse Migration as the Gaining Supplier / Agent
Qualified Parties Checklist
All Qualified Market Participants must also ensure they are ready for these changes from when MHHS Metering Points start to be migrated/accepted:
- Systems updated to record Market Segment against MHHS Metering Points, rather than Measurement Class
- Systems updated to store and utilise Cumulative Meter Readings for Smart Metering Assets and Advanced Metering Assets for settlement purposes
- Note that for Advanced and Traditional Metering Assets, Meter Register Readings will also be shared via existing DTN market messages (D0010); Suppliers can choose which meter readings to use for billing purposes
- Systems updated to recognise that date elements are to be shared in datetime format when sent via the Data Integration Platform
- Systems and processes updated to recognise the link between Related Metering Points including automatic agent appointment / de-appointment for Secondary Metering Points
- Systems and processes updated to recognise the link between Associated Import/ Export Metering Points including automatic agent appointment / de-appointment for Export Metering Points.
- Systems and processes updated to obtain and store Meter Technical Details (MTDs) from the SMRS
- Note that for Advanced and Traditional Metering Assets, supplementary MTDs will also be shared via existing DTN market messages (D0268 and D0149 / D0150).
- Systems updated to trigger message replay requests via the Data Integration Platform (DIP) to support error resolution
- Controls in place to meet new SLAs including
- 60-minute SLAs for processing certain DIP messages
- 120-minute SLA for Losing MOA sending MTDs
- 3WD SLA for issuing meter updates following meter works
- Controls in place to manage new DIP messages, including mechanism for dealing with message validation exceptions
- Controls in place to manage MTD exceptions identified through reconciliation of data received from SMRS and the relevant MOA.
- Business process and system updates (with associated DIP messages) to recognise the revised approach to managing Supplier Agent appointments, recognising the roles of the SMRS in validating appointment requests and acceptances and the effective from datetime aligning to midnight local time
- Business process and system updates (with associated DIP messages) to recognise the revised approach to managing meter works, including the change of energisation process, recognising the roles of the SMRS in validating MTDs and sharing via the DIP
- Business process updates (with associated DIP messages) to recognise the revised approach to managing Related Metering Point associations, recognising the roles of the SMRS in validating Related Metering Point requests and sharing details via the DIP
- Development of new business process for managing change of Market Segments as a result of a change in Connection Type and / meter exchange
- Development of new business process for managing MHHS Migration via the Switch or Change of Agent processes
All Market Participants should note that the following processes will remain unchanged when MHHS is implemented:
- Process for requesting meter works, including meter installation, removal and exchange, change of energisation and fault resolution. Supplier requests to the MOA/DNO still utilising the existing DTN messages, although new mechanisms will be in place for receiving the post meter work updates
- Process for sharing Site Technical Details between DNOs, Suppliers and MOAs
- Process for Commissioning Advanced Metering Assets and sharing data between DNOs and MOAs
- Process for managing supplier exceptions as set out in REC Schedule 30 ‘Resolution of Consumer Facing Switching and Billing Issues’ except the changes to the Switch Meter Read Exceptions process and applicability of Erroneous Switch processes to all electricity Metering Points
Distribution Network Operators - additional
M10 (MHHS go-live) Checklist
All DNOs must ensure they are ready for these changes at MHHS Go-Live (M10):
- Change to the ERDS to CSS agent appointment update to recognise Smart Meter Data Retrievers (SMDR) (R0044 and R0097)
- Change to data populated by DNOs as part of a New Connection, noting that all New Connections will be established as MHHS Metering Points, with associated MHHS data attributes from M10
Qualified DNOs Checklist
DNOs must also ensure, as Qualified parties at Go-Live, that they are ready for the following changes from when MHHS Metering Points start to be migrated/accepted:
- Systems updated to send and receive registration data updates via the DIP
- This includes receipt of updates to Metering Point Location Address, Domestic Premises Indicator, Energy Direction Indicator, Metered / Unmetered Indicator, DCC Enrolment, IHD information, SMSO Id, Profile Class and Standard Settlement Configuration
- Controls in place to manage missing agent appointment notifications and invalid Market Segment notifications (IF-045)
Electricity Suppliers - additional
M10 (MHHS go-live) Checklist
All Electricity Suppliers, regardless of when they qualify for MHHS, must ensure they are ready for these changes at MHHS Go-Live (M10):
- Changes to Supply Number content (R0083) - R0083 - Guidance for Supply Number population V2.0
- Change to data populated by DNOs as part of a New Connection, noting that all New Connections will be established as MHHS Metering Points, with associated MHHS data attributes from M10.
- Changes to D0311 Market Message
- Requirement removed by programme: Suppliers to ensure Appointed MOAs re-programme NHH Advanced Meter clocks to record time in UTC on or before the MHHS Migration EFD, provided that this activity is completed before the NHH Advanced Meter is used to support MHHS processes within British Summer Time
- If reprogramming is not possible within this timeframe, the Metering Asset shall be replaced
Qualified Suppliers Checklist
- Electricity Suppliers must ensure they are ready for these changes from when they start to migrate/accept MHHS Metering Points:
- Systems updated to send and receive registration data updates via the Data Integration Platform (DIP)
- This includes receipt of updates to Metering Point Location Address, Domestic Premises Indicator, Energy Direction Indicator, Metered / Unmetered Indicator, DCC Enrolment, IHD information, SMSO Id, Profile Class and Standard Settlement Configuration
- Controls in place to manage missing agent appointment notifications and invalid Market Segment notifications (IF-045)
- Business process updates to recognise the revised approach to managing Switch Meter Read exception
Electricity MEM/Meter Operator Agent - additional
M10 (MHHS go-live) Checklist
All Electricity MEMs/MOAs, regardless of when they qualify for MHHS, must ensure they are ready for these changes at MHHS Go-Live (M10):
- Changes to D0303 Market Message
- Requirement removed by programme: Suppliers to ensure Appointed MOAs re-programme NHH Advanced Meter clocks to record time in UTC on or before the MHHS Migration EFD, provided that this activity is completed before the NHH Advanced Meter is used to support MHHS processes within British Summer Time
- If reprogramming is not possible within this timeframe, the Metering Asset shall be replaced
Meter Asset Provider - additional
Changes Required for M10 (MHHS go-live)
All Meter Asset Providers must ensure they are ready for these changes at MHHS Go-Live (M10):
- Changes to D0303 Market Message
- Requirement removed by programme: Suppliers to ensure Appointed MOAs re-programme NHH Advanced Meter clocks to record time in UTC on or before the MHHS Migration EFD, provided that this activity is completed before the NHH Advanced Meter is used to support MHHS processes within British Summer Time
- If reprogramming is not possible within this timeframe, the Metering Asset shall be replaced
A full MHHS Readiness Checklist Matrix is also available.
Further reading
• Market-wide Half Hourly Settlement (MHHS) Hub on the REC Portal