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Understanding MHHS
Market-wide Half-Hourly Settlement (MHHS) is a major industry-wide reform to how electricity usage is measured and settled.
Understanding MHHS and what it means for your electricity supply
The UK energy market is changing. Market-wide Half-Hourly Settlement (MHHS) is a major industry-wide reform to how electricity usage is measured and settled, designed to create a more accurate, flexible and efficient energy system. At SmartestEnergy, we’re committed to guiding our customers through this change clearly and confidently, managing the complexity behind the scenes while keeping you informed about what matters to your business.
What is Market-wide Half-Hourly Settlement?
Market-wide Half-Hourly Settlement (MHHS) is a significant regulatory change for the UK MHHS energy market, mandated by Ofgem and delivered by Elexon. It requires electricity consumption for all customers to be measured and settled using half-hourly data.
MHHS at a glance
Currently, many sites are settled using estimated or profiled data. MHHS replaces this with actual consumption data, creating a more accurate reflection of how and when electricity is used.
Large businesses have benefited from half-hourly settlement for many years. MHHS extends these proven advantages across the market, modernising settlement arrangements and supporting a smarter, more flexible energy system.
Why is MHHS being introduced?
MHHS energy reforms are designed to improve how electricity is settled across the market, ensuring MHHS electricity costs more accurately reflect how and when energy is used.
How customers will benefit from MHHS
Many of the benefits of MHHS happen behind the scenes, but they create long-term value for customers. Customers moving from non-half-hourly settlement may see the greatest change, as billing and settlement become more closely aligned to actual consumption.
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Fairer, more accurate settlement
Reduced reliance on estimated billing and improved transparency.
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Improved energy management
Access to richer data to support insight-led decision-making.
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A more stable electricity system
Better network data helps balance supply and demand more effectively.
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Fewer disruptions
Less need for manual meter reads or engineer visits.
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Supporting sustainability goals
More accurate data supports efficiency initiatives, reporting and the transition to a lower-carbon energy system.
SmartestEnergy, your partner through the MHHS transition
As an experienced business electricity supplier, SmartestEnergy is preparing for MHHS energy changes by enhancing systems, processes and industry coordination well ahead of migration.
We are:
- Enhancing our systems and processes to fully support half-hourly data and MHHS settlement requirements.
- Training our teams to provide clear, expert guidance throughout the transition.
- Working closely with trusted industry agents and technology partners to ensure changes are coordinated and customer-focused.
We’ll manage the migration for you and keep you informed at every stage.
The MHHS timeline
What you need to do now
For most customers, no immediate action is required. If we need anything from you, we’ll contact you directly with clear guidance. However, a few simple checks now can support a smooth transition:
Customers who wish to unlock the full benefits of MHHS sooner may also choose to review their metering arrangements or energy usage patterns. We can support you with this when the time is right.
Frequently asked questions
When will my sites be migrated to MHHS?
The industry is migrating in waves from Octover 2025 to May 2027. SmartestEnergy customers are scheduled for Wave 3, running from August 2026 to May 2027. We’ll confirm your migration timing directly in advance.
Will it cost me anything?
No. There is no migration cost to customers. SmartestEnergy will manage the process.
Will my contract or prices change because of MHHS?
No. Your contracted rates, terms and tariff structure remain unchanged for the full contract term, including future-dated contracts. Any tariff changes would only occur at renewal, not mid-contract.
Do I need a smart or advanced meter?
Most customers do not need to take action right now. Smart and advanced meters help unlock the full benefits of MHHS, but we’ll contact you directly if a site visit or meter upgrade is recommended.
Existing customers will be supported by our team. New customers can check eligibility for a free meter exchange as part of the switching process.
I’m already half-hourly, does anything change for me?
Yes, but mainly behind the scenes. All customers, including those already half-hourly, will migrate to the new MHHS arrangements. You’ll see updated MPAN topline formatting, but your billing and contracts remain unchanged.
I’m a generation customer, will I be impacted?
Yes. Generation customers will also migrate to MHHS arrangements and see updated MPAN topline information. Settlement timelines will align with the new MHHS framework from July 2027.
What does “migration” actually mean?
Migration is the process of moving your Meter Point Administration Numbers (MPANs) to the new MHHS settlement arrangements. All customers will be settled on a half-hourly basis once migrated.
How will meters be classified under MHHS?
Under MHHS, portfolios will be grouped by meter type rather than HH or NHH:
- Advanced – existing HH or AMR meters
- Smart – smart and traditional Non-Half Hourly meters
- Unmetered – unmetered supplies
What will I see change on my bill or day to day?
During your current contract, billing arrangements stay the same. Settlement will use more accurate half-hourly data behind the scenes. We’ll notify you before any visible changes occur.
Can all my sites be migrated at the same time?
We aim to migrate all MPANs within the same window, but this may not happen on a single day. We’ll plan migrations to minimise disruption and keep you informed.
Get in touch
We’re here to support you throughout the MHHS transition. If you have questions about MHHS or your electricity supply, contact our dedicated inbox: SEL-MHHS@smartestenergy.com