For major energy users, Market-wide Half-Hourly Settlement (MHHS) isn’t just another regulatory change. The choices you make now about your data and metering infrastructure partners will directly impact your energy costs, billing accuracy, and operational efficiency for years to come.
Yet many businesses remain underprepared. The consequences of inaction are clear: estimated bills, unexpected manual read charges, and lost opportunities to optimise consumption. This article explains what MHHS migration means for your organisation and why preparation cannot wait.
Understanding MHHS migration and its timeline
MHHS migration is the process of moving all electricity supplies from the current settlement system to a new framework that settles all meters on a Half-Hourly (HH) basis. Currently, the market operates a dual system with both HH and Non-Half Hourly (NHH) settlement. MHHS eliminates this. MHHS is important because it opens opportunities to use more Time of Use (ToU) tariffs and gives more control over energy costs.
During migration, existing data collectors and meter operators are de-appointed from the old system and re-appointed to the new MHHS infrastructure. Your energy supplier coordinates this transition with their appointed agents, but the readiness of your metering estate determines whether migration proceeds smoothly or becomes a costly disruption.
Migration is occurring in carefully orchestrated waves. Each supplier needs to qualify for MHHS ahead of their wave to start migration of their supplies. When you migrate to MHHS depends on who your electricity supplier is, and which wave they are in. Migration started October 2025 and ends May 2027. More accurate data means more accurate bills.
The cost of poor metering infrastructure
MHHS requires accurate HH data collected remotely from all meters. If your metering estate cannot deliver this, you will face significant additional costs. Meters that require manual reads are incompatible with MHHS’s strict data quality targets. Under the current system, some meters might be read monthly or quarterly. Under MHHS, you’ll need accurate data every settlement period, meaning far more frequent manual reads if your meters cannot transmit data remotely.
Each manual read carries a cost. Multiply that across a large estate and frequent collection periods, and you’re looking at tens of thousands of pounds in unexpected charges. But the financial impact doesn’t stop there.
Without reliable HH data, your bills will be based on estimates rather than actual consumption. These estimates typically overcharge because they’re based on historical patterns and don’t account for recent efficiency improvements or changes in operational patterns. You’ll be paying for energy you didn’t use, with no visibility to challenge the charges effectively.
Plus, poor data quality makes it impossible to unlock ToU savings. ToU tariffs will be more prevalent under MHHS, but without the data and metering infrastructure in place, you lose the ability to shift demand to off-peak periods.
What your organisation must do now
Preparation for MHHS migration requires action in three key areas: understand your timeline, audit your metering estate and ensure you have qualified, high-performing agents in place.
1. Establish your migration timeline. Ask your supplier when your migration will occur. If you operate across multiple sites with different suppliers, you may face migration at different times. Map this out so you can prioritise preparation efforts.
2. Conduct an audit of your metering infrastructure. NHH meters should have faults identified and remote data collection enabled. Advanced (AMR) or Smart (SMETS) meters should have faults fixed and remote data collection enabled. Any traditional meters must be upgraded or replaced before migration. HH meters need re-appointments monitored. Your data and meter agents will be de-appointed and need to be re-appointed into the new MHHS. Make sure your preferred data and meter agents are being re-appointed.
3. Ensure your data collector and meter operator are qualified for MHHS. Not all metering agents are created equal. Performance varies significantly across the market, and this directly affects your costs. At Stark, we’ve been collecting HH energy data for over 40 years, and we’re the best-performing data and metering agent combination for settlement data in the market. We’re also the only agent qualified to dial all meter types and deliver all MHHS services under a single provider.
The strategic importance of data quality
Senior leaders must recognise the impact of data quality. High-quality HH data is foundational to nearly every energy management objective your organisation might have. Sustainability commitments require accurate measurement. Energy procurement becomes more sophisticated with granular data. Operational efficiency improvements depend on understanding where and when energy is consumed.
The businesses that emerge from MHHS migration strongest will be those that viewed it not as a compliance exercise but as an opportunity to establish best-in-class energy data infrastructure. Poor preparation means you’ll be playing catch-up for years.
Act now
MHHS migration is underway. Your supplier has a strict migration timeline. The clock is ticking. Organisations that act now will migrate smoothly, maintain accurate billing, and position themselves to capitalise on the opportunities that HH settlement creates. Those that delay will pay for it in estimated bills, manual read charges, and lost opportunities.