Operational Foresight in a Market-wide Half-Hourly Settlement World

By Richard Carnall, Head of Consulting Services

Market-wide Half-Hourly Settlement (MHHS) is the biggest change to the way the energy industry settles consumption in a generation. It brings richer data, new market messages and tighter deadlines, all at the same time. For energy suppliers, that combination can feel like a recipe for more firefighting.

Handled well, though, it can have the opposite effect: a shift from reacting to problems after the fact to spotting and preventing them early.

We recently went over some of the biggest impacts of MHHS on data handling and revenue assurance in our webinar “The Data Explosion: From Financial Firefighting to Operational Foresight Through the MHHS Transition”​. This article continues that by exploring what’s changing, where the risks sit, and how a more proactive approach can protect revenue and strengthen settlements performance.

What’s Actually Changing Under MHHS?

MHHS retires or repurposes many of the legacy market messages and introduces new ones, delivered through a new Data Integration Platform.

Roles are changing too. Data collectors, data aggregators and meter operators are giving way to data services and metering services, appointed according to the segment each customer falls into. A site with a smart meter, for example, needs a different type of data service from one with a traditional meter.

Two further changes matter for commercial planning. Settlement timescales are shrinking, and supplier charges are expected to reflect settlement performance, with some form of league table rewarding strong performers and incentivising improvement among the rest.

The upsides

The benefits are genuine. More reads mean less reliance on estimates, and where estimation is still needed, a more sophisticated load shaping methodology will apply.

Daily half-hourly consumption improves visibility of demand, helps network operators manage the grid, and opens the door to time-of-use tariffs, demand response and cheaper, cleaner energy. All of this, however, depends on one thing: being able to handle the data.

The Data Explosion

Under the legacy arrangements, a typical non-half-hourly MPAN delivers a single read each month. Under MHHS, that becomes a daily payload of 48 half-hourly intervals. Over a 30-day month that means around 1,440 intervals, and across a year the figure climbs from 12 data points to roughly 17,500. It all arrives in new, JSON-based messages carrying new content.

The practical consequences are significant:

Technology must do more than store data. Systems need to ingest, validate, process and present information at scale, in a form people can actually use.

• Two arrangements will run in parallel. Legacy and MHHS data must both be processed for a time, with the hosting costs that implies.
• Retention needs careful thought. Reports are sometimes rerun by reloading raw data, which becomes expensive and cumbersome if large volumes are held for long periods.
• Aggregation is essential. Half-hourly data is far too voluminous for portfolio-level reporting in its raw form, so it must be arranged by portfolio, site or month before it can be analysed.

Granular data makes it possible to see small changes within a 24-hour period that were previously invisible. That only becomes valuable, though, when it is turned into insight that someone can act on.

A Shrinking Window For Correcting Errors

As of October 2026, the RF settlement window reduced from 14 months to seven. Subject to confirmation, a further reduction to four months is expected from April 2027, pending a decision due in March 2027. The first settlement run, SF1, is also due to fall from 15 working days to seven in July 2027.

Fluidity of settlements

Because these changes land at different times, suppliers will find themselves managing a patchwork. Consumption for September 2026 sits under the 14-month arrangements, while October 2026, just one month later, is under the 7-month arrangement. A similar split will appear between March and April 2027.

The result is that anyone wanting to query last year’s charges will meet a mix of periods that are still open to adjustment and others that are already closed. Prioritising the periods approaching crystallisation, and forecasting the value of potential recoveries, becomes a vital discipline.

Why the old approach no longer works

Many suppliers already find the 97% actual-energy target difficult at 14 months. At four months, the expectation moves much closer to 100%, with performance published in league tables. The traditional cycle of reporting on the data, identifying errors, querying them and waiting for later settlement runs simply no longer leaves enough time.

Preventing errors and investing in a strong reads strategy that will prevent errors rather than correcting them is the only sustainable route forwards.

Migration Risks to Watch

The next 12 to 18 months will be dominated by migration. The early experience across the industry is encouraging: the issues seen so far have largely been teething problems, mostly data-related, and nothing show-stopping. Even so, several themes keep recurring.

Appointments

Every site must be de-appointed from its legacy data collector and aggregator and appointed to the relevant data services. The goal is no open appointments and no gaps between appointment periods.

Where old and new arrangements aren’t closed out and reconciled correctly, data can be duplicated and settlement impacted. An industry change due in November 2026 is intended to reduce this risk and the double counting that comes with it.

Assets, segments and consumption

Converting non-half-hourly AMR devices to half-hourly at the point of migration has created billing challenges. Market segments can also default incorrectly where meter details are missing, leading to parties assuming a site is smart when it is not.
Insufficient information in the central platform has at times produced inaccurate annual consumption figures, forcing suppliers to provide their own.

Consent granularity and contract references

The most frequent issue across go-lives has been consent granularity. It pays to check what each meter and its settings actually permit, rather than assuming. Contract references are another common stumbling block: agreements may be in place, yet messages are rejected because the reference has not been set up in another party’s system.

Rejections leave open appointments, so every party in the supply chain needs to be involved and the references confirmed everywhere.

Data quality and estimation

More granularity doesn’t automatically mean better quality. The data arriving needs to be validated, including settlement period consumption data and its warnings, and its downstream impact understood.

Estimation won’t disappear overnight either, because a large number of traditional meters remain in the market. At portfolio level, performance can look stable, while a closer look at individual sites reveals outliers.

Poor estimation at a single site can have a material impact, so it deserves investigation rather than being treated as noise. It’s also worth checking that current processes reflect the intended charging treatment of migrating customers, including the adjustments introduced under CMP430.

Moving From Firefighting to Foresight

The common thread through all of this is proactivity. Here’s what that means in practice.

Build your strategy on exception lists

Complete, up-to-date data allows you to create exception lists, and exception lists reveal root causes. Too many organisations still work through their reads from top to bottom, rather than targeting higher volumes or easier wins first.
Typical root causes include failing assets, inaccessible sites, erroneous read data and onboarding issues. All are manageable once they’re visible and quantified.

Treat missing reads as a relationship challenge

The biggest single driver of poor read performance is simply a lack of reads. That shifts the task from data management towards account management: working with data services, metering services and customers to secure site access and improve performance together.

With some suppliers already facing restrictions, collaboration benefits everyone.

Stay close to change, and share what you learn

MHHS adds more touch points to every process, and change proposals are arriving at pace. Each one needs an impact assessment, validation, a considered response and then implementation across systems and operations. Engaging early through industry forums gives visibility of what is coming, and raising challenges collectively carries more weight than a single voice. Open communication between every party in the chain makes a real difference when something goes wrong.

Turning Disruption Into Advantage

MHHS will test every supplier’s data capability, but it also rewards those who prepare. The organisations that cope best will treat granular data as a source of foresight: using it to prioritise the right fixes, protect revenue before settlement windows close, and move calmly through migration.

ESG Global’s consulting team has spent 16 years helping suppliers turn granular energy data into recovered revenue, and we’re currently supporting clients through every stage of migration.