Can the Energy Industry Keep up With MHHS?

The UK energy sector has long been working toward more accurate, transparent, and efficient settlement systems. In 2025, those efforts are accelerating under Ofgem’s mandate for Market-wide Half Hourly Settlement (MHHS). On paper, the migration promises big wins: better alignment of pricing and settlement, smoother integration of renewables, and a pathway toward Net Zero.

But while MHHS represents an important step forward for the industry and for consumers, the transition has exposed significant cracks in readiness, technology, and fairness. For suppliers and their partners, the question is whether the industry is truly prepared to meet the deadlines or whether it’s time to pause and rethink.

What is MHHS?

Market-wide Half Hourly Settlement (MHHS) is a reform of electricity market arrangements designed to enable a more flexible, cost-effective, and sustainable energy system. Instead of relying on estimated or infrequent meter reads, MHHS uses half-hourly data for all settled energy. This accuracy helps suppliers balance their portfolios, encourages consumers to shift demand to off-peak times, and supports the integration of renewable energy.

In practice, MHHS involves a phased migration of MPANs (Meter Point Administration Numbers) by supplier. Each phase requires suppliers to reconfigure their systems for new Settlement Configuration (SSC) IDs and updated Line Loss Factors (LLFs), replacing older identifiers like the Meter Time Switch Code (MTC).

The goal is to empower consumers with better tariffs and give the industry the tools to accelerate Net Zero. The challenge lies in execution.

Smart Meters are the First Roadblock

A critical part of MHHS success depends on widespread adoption of smart meters. Yet progress has been slower than expected. Despite years of promotion, 42% of UK meters are still not smart. That translates to millions of devices—around 30 million in total—that need upgrading to be MHHS-ready, including 2.6 million business meters.

For suppliers, this creates a double bind. Without smart meters, customers cannot participate fully in MHHS, but replacing them at scale before the 2025 deadlines is a monumental task. Older pre-smart meters present another hurdle because many cannot be transitioned at all.

The result? A transition plan that looks good on paper but runs into a wall in practice.

A Phased Rollout with Ripple Effects

Ofgem’s migration plan begins in September 2025, when the first group of suppliers—likely including two of the “big six”—must switch to half-hourly billing. Four phases are scheduled across a one-year period, ending in 2026, with full industry-wide migration set for 2027.

While phased rollouts are intended to manage complexity, in this case, they may be making matters worse. Each supplier in an earlier phase must reformat Top Line Supply Numbers differently, creating ripple effects across billing systems, customer invoices, and industry databases.

For suppliers, this means their systems must be capable of handling both old and new formats simultaneously. This is a significant technical challenge, especially for those with legacy billing platforms. For customers, it could mean inconsistent billing and confusion.

Uneven Supplier Readiness

One of the most pressing issues is inconsistency. Because each supplier interprets Ofgem’s requirements differently and has different technical stacks, the industry faces a patchwork of solutions. Some larger, more advanced suppliers can absorb the complexity, but smaller or less digitally mature companies are at a disadvantage.

For those unable to process the new Top Line Supply Numbers, taking on new customers in MHHS becomes impossible. That creates an uneven playing field, where competitive advantage is determined less by service or price, and more by IT readiness.

This undermines the very principle of MHHS which is to ensure consumers have access to the best, most appropriate deals.

The Energy Industry is Unprepared

MHHS was meant to increase accuracy, stability, and consumer benefit. But with the industry racing to meet deadlines while juggling smart meter replacements, system overhauls, and inconsistent approaches, the reality looks much different.

Suppliers face mounting hurdles across the downstream supply chain, while customers may not see meaningful benefits until at least 2027, when the migration is complete. Even then, the introduction of time-of-use tariffs, the true consumer-facing value of MHHS, is still years away.

The result is reform designed to deliver fairness and transparency may, in the short term, create confusion and inequity.

Is It Time to Push Back on MHHS?

No one doubts the importance of MHHS for achieving Net Zero and empowering customers. But the industry’s lack of preparedness raises a difficult question…

“Should we be pressing pause?”

A delay could give suppliers more time to:

• Accelerate smart meter adoption.
  
  
• Standardize approaches to Top Line Supply Numbers.
  
  
• Level the playing field for smaller suppliers.
  
  
• Ensure systems are tested and resilient before going live.

Without this breathing room, MHHS risks creating instability instead of solving it. This undermines confidence from suppliers and customers alike.

Moving Forward with MHHS

Market-wide Half Hourly Settlement represents a bold vision for the UK energy industry. It promises accuracy, flexibility, and sustainability. But the road to implementation is fraught with practical obstacles. Unless the industry can align on timelines, standards, and system readiness, MHHS may become another well-intentioned reform that fails to deliver in practice.

For suppliers, the next year is critical. Engage now in preparation, collaboration, and advocacy. As the September 2025 deadline looms, the industry must ask itself a tough but necessary question…

Is it better to push ahead unprepared, or push back until we’re ready to deliver on MHHS’s promise?