Half‑hourly settlement a year after MHHS reforms for UK businesses

A year after Ofgem introduced market‑wide half‑hourly settlement (MHHS), the impact on UK businesses is becoming measurable: more granular data is unlocking new tariff structures, driving cost efficiencies and exposing contracts that still rely on outdated half‑hourly‑agnostic pricing.

What MHHS changed

Granular consumption data

MHHS requires all non‑exempt electricity meters to submit half‑hourly (HH) readings to the system operator. This replaces the historic half‑hourly settlement (HH) regime that applied only to large generators and a small subset of large consumers. For most businesses the change is invisible on the front‑end, but on the back‑end the data feed feeds directly into the balancing mechanism, enabling more accurate settlement and, crucially, the creation of tariffs that reflect true consumption patterns.

New tariff categories

With HH data in the market, suppliers can now offer three distinct tariff families:

• HH‑specific tariffs – priced on the actual half‑hourly profile, often with time‑of‑use (TOU) or peak‑shaving components.
• Hybrid tariffs – a blend of HH‑derived charges for peak periods and traditional flat rates for off‑peak.
• Legacy non‑HH tariffs – still permitted for small, exempt sites but increasingly out‑competed as the market matures.

Ofgem’s MHHS rulebook (2023) mandates that suppliers publish the methodology used to calculate HH‑derived charges, providing transparency that was previously missing.

Opportunities for UK businesses

Access to HH‑specific tariffs

The most immediate benefit is the ability to negotiate tariffs that reward low‑usage periods. For a typical 200 kW site, moving from a flat rate of 12 p/kWh to a TOU tariff that charges 8 p/kWh during off‑peak and 15 p/kWh at peak can shave 5‑10 % off the annual electricity bill, depending on load shape. The savings are amplified when combined with demand‑side response.

Flexibility services and demand response

Because HH data feeds the balancing mechanism in real time, businesses can now participate in capacity market contracts, frequency response and other ancillary services without the need for bespoke metering. TUS Group currently manages over 150 GWh of flexibly‑controlled consumption and has beat supplier projections by 20 % in the last 12 months, demonstrating that even mid‑size sites can generate revenue streams from flexibility.

Key steps to capture this value:

1. Map the half‑hourly load profile to identify peak windows.
2. Enrol in a demand‑response programme that offers a per‑MWh payment for load reduction during System Operator (NESO) call‑outs.
3. Use automated controls or simple manual shifting to meet the call‑out, ensuring that the cost of any operational change is less than the market payment.

Voltage optimisation and other on‑site savings

While MHHS focuses on energy settlement, many businesses overlook power quality. Voltage optimisation can deliver 5‑15 % reduction in kWh consumption with a typical payback of 2‑3 years. When combined with HH‑aware tariffs, the cumulative effect can push total electricity cost reductions beyond 15 % for energy‑intensive sites.

Switching with the Yolk portal

TUS’s free Yolk portal aggregates the latest HH‑compatible offers from a 30+ supplier panel. Users who have switched through Yolk report an average 27 % saving on their electricity spend, driven by the ability to compare true HH‑derived rates rather than flat‑rate proxies.

When your contract still treats you like a non‑HH meter

Identify the mismatch

The first sign of a legacy contract is a flat‑rate invoice that does not reference half‑hourly data, even though the site is now required to submit HH readings. Compare the invoice’s settlement methodology with the data published on the Ofgem portal; any discrepancy is a negotiation lever.

Steps to renegotiate

1. Gather evidence – Export the last six months of HH data from your Energy Management System (EMS) and calculate the theoretical HH settlement using the published Ofgem methodology.
2. Benchmark – Use the Yolk portal to obtain at least three comparable HH‑specific tariff quotes from the 30+ supplier panel.
3. Engage the supplier – Present the benchmark and request a contract amendment that aligns settlement with HH data. Highlight that Ofgem expects suppliers to treat HH‑enabled sites fairly under the MHHS rulebook.
4. Escalate if needed – If the supplier refuses, lodge a complaint with Ofgem’s Consumer Protection team, referencing the MHHS compliance obligations.

Leverage TUS expertise

TUS can audit your existing contract, model the financial impact of moving to an HH tariff and, where appropriate, manage the transition to a new supplier via Yolk. Our experience with 150 GWh of flex management means we understand the interplay between tariff selection, demand response and on‑site optimisation, ensuring you capture the full value of the MHHS regime.

Bottom line

MHHS has turned half‑hourly data from a compliance requirement into a commercial asset. Businesses that adopt HH‑specific tariffs, participate in flexibility markets and optimise voltage can realise double‑digit savings, while those stuck on legacy contracts risk overpaying and missing revenue opportunities. Review your settlement methodology, benchmark against the 30+ supplier panel on Yolk and, if needed, enlist a specialist such as TUS to secure a contract that reflects the true cost of your electricity use.