MHHS-related REC Guidance Homepage

This article signposts to guidance that has been published by the REC Code Manager as part of, or since Market-wide Half Hourly Settlement (MHHS) Go-Live on 22 September 2025. This guidance is provided in addition to the MHHS design, that is now captured in the industry codes, and supports REC Party understanding of MHHS specific scenarios.

The guidance has, and will be, updated from time to time as lessons are learnt through MHHS Early Life Support and queries are received into the REC Service Desk and other service desks.

Registering New Connections during MHHS Transition Period

The following article provides guidance on how New Connections and Initial Registrations are to be managed during the (MHHS) Transition period, until Migrations are completed at MHHS Milestone M15, Registering New Connections during MHHS Transition Period.

Standard Settlement Configuration, Time Pattern Regime and Profile Class

Queries are commonly being received in relation to how the use and sharing of certain Data Items has been changed under the MHHS arrangements. Primarily, the queries relate to the Standard Settlement Configuration, Time Pattern Regime and Profile Class Data Items. There have also been some queries on the Meter Timeswitch Code.

Guidance on all these Data Items can be found in the following REC Wiki articles:

In addition, the Sharing of SSC for MHHS Smart and Advanced Meters - Interim Guidance document has been created under REC Issue I0273. This interim guidance is intended to support Parties specifically during the MHHS migration period and establishes expected behaviours and good practice to maintain data integrity, continuity of service, and market operability.

It should be noted that Profile Class is a BSC owned Data Item and any further queries on its population and use in the MHHS arrangements should be raised with Elexon Support.

For specific guidance on population of the Supply Number, see the R0083 - Guidance for Supply Number population V2.0.

D0150 Guidance for MHHS Reverse Migrations

The following REC Wiki article provides guidance on how to populate mandatory Data Items in the skeleton D0150 - Traditional Meter Technical Details on a Reverse Migration, D0150 Guidance for MHHS Reverse Migrations.

Meter Technical Details for NHH Metering Points, Reverse Migrated from Advanced

There is a scenario where a Metering Point can have been operating in the Advanced Market Segment under MHHS, and then when Reverse Migrated and the new Supplier opts to operate it under Non-Half Hourly (NHH) arrangements. The Meter Operator Agent (MOA) will therefore need to provide NHH Meter Technical Details (MTDs) but will have received Half Hourly MTDs as part of the Reverse Migration.

The Population of NHH MTDs when Reverse Migrated from Advanced guidance document has been created to support MOAs and Suppliers in managing this scenario.

The Sharing MTDs on MHHS Reverse Migrations, no Gaining MOA details article provides guidance to Meter Operator Agents (MOAs) on expectations related to missing Gaining MOA details impacting the ability to send MTDs following de-appointment as part of a Reverse Migration.

Using SDEP to communicate with SMRS for MHHS Queries

As part of the MHHS Service Management process, participants may need to raise queries with the Supplier Meter Registration Service (SMRS). This would be for queries under the new MHHS arrangements from MHHS Milestone M11 & M12 (Migration Start, 22 October 2025) through to MHHS Milestone M15 (Migration completion, May 2027) and which include the sharing of MPAN or address information.

The Using SDEP to communicate with SMRS for MHHS Queries guidance has been developed as an additional resource to help parties navigate these processes efficiently and securely.

Data Alignment of Meter Information Through MHHS Migration

REC Issue I0240 was raised to address that when Meter updates are made during a Market-wide Half Hourly Settlement (MHHS) Migration, whilst the Meter Technical Details (MTDs) will be shared between participants, there will be no update sent to the Registration Service as the Gaining Meter Operator Agent (MOA) will not know that they need to send a D0312 (for Reverse Migration) or IF005 (for Forward Migration) and the Losing MOA cannot send the message.

The issue was resolved through the development of scenario guidance to ensure REC Parties are aware of the appropriate steps to take when meter information is updated during the period of a Metering Point's migration. The I0240 - Data Alignment of Meter Information Through MHHS Migration - Scenario Guidance Document V2.0 was published on 30 April 2026.

Meter Install EFD earlier than Meter Point Creation Date

The following article provides guidance to Meter Operator Agents (MOAs) operating in the Electricity Market-wide Half Hourly Settlement (MHHS) market, who are receiving objections from the Supplier Meter Registration Service (SMRS) when attempting to update Meter Technical Details (MTDs) where the DI-057 ‘Meter Installation Date and Time’ is prior to the ‘MSID Creation Date’ held by SMRS, Meter Install EFD Earlier than Meter Point Creation Date.

MHHS Metering Guidance

Category 3 documents providing guidance on metering process under MHHS arrangements were implemented as part of the REC release for MHHS on 22 September 2025:

Energisation Status Effective from Date discrepancy in EES and SMRS

This article is to provide guidance to Electricity Enquiry Service (EES) Users on a known data misalignment between EES and the Supply Meter Registration Service (SMRS) around the Energisation Status Effective from Date (EFD) for Market-wide Half Hourly Settlement (MHHS) Metering Points, Energisation Status Effective from Date discrepancy in EES and SMRS.

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