Understanding MHHS

The biggest change to electricity settlement in 30 years. Market-wide Half-Hourly Settlement changes how consumption is measured and charged across Great Britain.

What is MHHS?

Historically, only large business meters recorded exactly when electricity was used, in 30-minute intervals. Everyone else had their usage estimated from typical patterns for their customer type (Profile Classes 01 to 08).

MHHS changes this. By May 2027, all meters, including smart meters in homes and small businesses, will be settled on actual half-hourly data rather than estimates.

Your charges will reflect when you use electricity, not just how much. That opens the door to smarter energy management and more accurate validation.

Key timeline

1. Sep 2025: MHHS go-liveNew MPAN format and central systems ready
2. Oct 2025: Migrations beginSuppliers start moving meters to HH settlement
3. Oct 2026: 80% targetMajority of meters migrated
4. May 2027: Full completionAll meters on half-hourly settlement

The MPAN format change

Legacy MPANs are 21 digits; MHHS MPANs are 22. The extra digit comes from the SSC (Standard Settlement Configuration), a 4-digit code replacing the 3-digit MTC.

• Profile Class becomes 00. Migrated meters use PC 00: actual data replaces profile estimation.
• SSC replaces MTC. A 4-digit Standard Settlement Configuration, standardised nationally.
• LLFC unchanged for DUoS. Your tariff category link stays the same, so validation still works.

Key MHHS concepts

• SSC (Standard Settlement Configuration)A 4-digit code replacing the legacy MTC. Each SSC defines how many meter registers exist and which time periods each register captures.
• TPR (Time Pattern Regime)Defines exactly which half-hours each meter register records. Essential for multi-rate tariffs like Economy 7, where switching times vary.
• Profile Class 00PC 00 in an MPAN means that meter has migrated to MHHS. Settlement uses actual readings, not profile estimation.

What this means for your business

• More accurate charges. Charges based on actual usage patterns, not statistical estimates.
• Better demand management. Shift usage to cheaper time periods, knowing your charges will reflect it.
• Validation works the same. LLFC still sets your DUoS tariff, and EnergyCode reads both MPAN formats.
• Your supplier handles the move. No action needed from you: migration happens automatically.

How EnergyCode helps

• MPAN decode. Detects the 21 or 22-digit format and extracts the right fields.
• MHHS reference lookup. Search SSC codes to see meter register configurations and TPR timing.
• Validation on either format. DUoS charges for legacy and MHHS-migrated meters alike.
• Enterprise API. Full SSC and TPR reference data for system integration.

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