UK businesses with a Maximum Import Capacity (MIC) above 100kW are required to have a half-hourly (HH) meter. Smaller businesses can be moved onto HH metering voluntarily or following the P272 and P322 mandate programmes. HH meters enable more granular billing, access to time-of-use tariffs, and the visibility needed for demand management. Installation and ongoing costs vary by supplier and data service provider.
Last reviewed: 12 May 2026
What Half-Hourly Metering Is and Why It Exists
A half-hourly (HH) electricity meter records consumption every 30 minutes and transmits that data to a data collector and data aggregator who feed it into the electricity settlement system operated by Elexon. Non-half-hourly (NHH) meters record a cumulative total that is read periodically, usually once or twice a year, with consumption estimated between reads.
The settlement system exists to balance the electricity market. At any point in time, the amount of electricity generated must match the amount consumed. Settlement is the process by which every supplier is financially credited or debited based on the difference between what their customers actually consumed and what the supplier contracted to buy. HH data makes settlement more accurate because it provides a 48-point consumption profile for every trading day rather than a single annual figure.
For businesses, HH metering has a direct billing implication: your electricity costs are calculated using actual half-hourly consumption data, matched against the wholesale prices in each settlement period, rather than a flat or two-rate estimated profile.
The 100kW MIC Threshold: When HH Metering Is Mandatory
The trigger for mandatory HH metering is the Maximum Import Capacity (MIC), sometimes called the agreed supply capacity. This is the maximum rate at which a business can draw electricity from the grid, set at the point of connection and recorded on the Distribution Use of System (DUoS) agreement with the DNO.
Businesses with a MIC above 100kW (kilovatts) are classified as mandatory half-hourly (MHH) customers and must have an HH meter installed. This threshold has been in place since the early 2000s. It applies to the supply point's registered capacity, not to actual peak demand observed in billing data, although in practice the two are related.
For businesses approaching the 100kW threshold, it is worth understanding what the MIC figure on your connection agreement actually is before assuming NHH metering applies. If your MIC was set at connection to allow for future expansion and exceeds 100kW even though actual demand is lower, HH metering is still mandatory.
P272 and P322: The Extension of HH Metering to Smaller Sites
The P272 modification, implemented by Elexon and the industry in April 2017, extended mandatory HH settlement to profile class 05-08 meters (customers consuming between approximately 50,000 and 200,000 kWh per year). These sites had NHH meters but were already capable of recording half-hourly data. P272 required their data to be settled on a half-hourly basis rather than using the estimated profile approach.
P322 followed as a further modification to address P272 implementation issues, including the treatment of sites where the meter could not transmit data reliably. The combined effect of P272 and P322 was that a large tranche of medium-sized business customers moved from NHH to HH settlement, in most cases without needing a physical meter replacement because their existing advanced meters already had HH capability.
The significance of P272 for businesses affected by it was twofold: first, billing became more accurate and more variable (because actual half-hourly consumption was matched against time-specific wholesale prices rather than a flat profile); second, access to time-of-use tariffs became possible, potentially reducing costs for businesses able to shift load away from peak periods.
Data Collectors and Data Aggregators: Their Roles in HH Billing
HH metering involves a chain of data services between the meter and the supplier. Understanding this chain explains why HH billing involves more parties and potentially more cost than NHH.
Data Collector (DC): The DC is responsible for retrieving half-hourly consumption data from the meter, validating and estimating it where necessary, and passing it to the data aggregator. The DC is appointed by the supplier but operates under Elexon licence conditions.
Data Aggregator (DA): The DA receives validated data from the DC and calculates the aggregate consumption values that feed into Elexon's settlement system. The DA reconciles consumption against the supplier's contracted positions.
Both the DC and DA charge for their services. These charges are typically passed through to the business by the supplier as part of the non-commodity cost element of the electricity bill. On a small HH-metered site consuming 200,000 to 500,000 kWh per year, DC and DA charges typically add £200 to £600 per year to the total bill.
Larger businesses on flex contracts or pass-through arrangements may see DC and DA charges itemised separately on the invoice.
Settlement Profile Classes Explained
Before P272, and still for businesses below the HH threshold, NHH customers are billed using estimated consumption profiles. Elexon assigns each meter point to a Settlement Profile Class (PC) that represents a typical consumption shape for that type of customer. Profile classes 01 to 04 cover domestic and small business customers; 05 to 08 cover larger non-domestic customers.
The profile is used to allocate a customer's total annual consumption across all 17,520 half-hour periods in the year, based on published shapes for that customer type. The allocated half-hourly figures are then used in settlement, meaning the supplier is buying electricity based on an estimated profile rather than actual consumption.
The practical implication for businesses on NHH metering is that their bill does not reflect actual peak consumption behaviour. If a business in profile class 03 consistently uses more energy during high-price morning peak periods and less during off-peak periods, the NHH settlement approach averages this out and the business pays neither more nor less because of its actual shape. Under HH settlement, a business with a peaky consumption profile would typically pay more, while one with a flat or off-peak profile would often pay less.
Capacity Charges and Half-Hourly Metering
HH-metered businesses are typically subject to capacity-related charges that do not apply in the same way to NHH customers. The two main capacity charges are:
Distribution Use of System (DUoS) availability charges: These are charged by the DNO on HH-metered sites based on the agreed supply capacity (MIC). They reflect the cost of maintaining network capacity available to the business whether or not it is used.
Triad charges: Large HH customers above certain consumption thresholds are exposed to Transmission Network Use of System (TNUoS) charges based on their demand during the three periods of highest national grid demand in the winter (the Triads). Triad exposure can add materially to the electricity cost of large industrial and commercial sites. Smaller HH sites in profile class 05-08 are not typically exposed to Triad charges but may be exposed to DUoS capacity charges.
For businesses newly moved onto HH metering under P272, understanding whether capacity charges now apply to their account is an important step in verifying their bill is correct.
What HH Metering Costs and When an Upgrade Is Forced
For businesses where HH metering is mandatory (MIC above 100kW), the supplier is required to arrange the meter installation. The meter itself is typically owned by the Meter Operator (MOP), a separate accredited party who installs and maintains the hardware under a Meter Operator Agreement. MOP charges are passed through on the bill and typically range from £100 to £500 per year for a standard commercial HH meter.
For businesses where HH metering is optional (MIC below 100kW but the business wants the granular data), the process is the same: appoint a MOP via the supplier and agree DC and DA services. The upgrade cost depends on whether the existing meter is advanced meter capable (in which case only a configuration change and data service appointment is needed) or whether a full physical replacement is required.
Physical meter replacement for a commercial site typically costs £300 to £1,500 in installation fees. Ongoing MOP, DC, and DA charges add £400 to £1,200 per year. The financial case for a voluntary upgrade depends on whether the business expects to benefit from time-of-use tariffs, demand management programmes, or improved billing accuracy.
For the change of tenancy context, if you are taking over a site that already has an HH meter, you inherit the MOP agreement as part of the supply point record. Check whether the MOP contract terms are favourable or whether you should negotiate new terms at the point of taking over the account.
Frequently asked questions
Editorial disclaimer: This information is provided for general guidance only. Half-hourly metering arrangements involve regulated energy industry processes. Seek advice from a licensed energy adviser or supplier if you are unsure of your obligations.
What does MIC stand for in electricity billing?
MIC stands for Maximum Import Capacity. It is the maximum rate at which a business's premises can draw electricity from the grid, agreed with the Distribution Network Operator at the point of connection and measured in kilowatts (kW).
What was the P272 modification and does it still affect my bill?
P272 was an Elexon modification implemented in 2017 that moved profile class 05-08 meters to half-hourly settlement. If your site was moved under P272, your billing has been based on actual half-hourly data since April 2017. The modification is no longer a transition process; it is now the standard settlement method for those sites.
Can I request a half-hourly meter if my MIC is below 100kW?
Yes. Any business can request an upgrade to HH metering regardless of MIC. The business will need to appoint a Meter Operator, Data Collector, and Data Aggregator through the supplier. The decision is usually worth making if the business wants access to time-of-use tariff structures or better consumption visibility.
What are Triad charges and do they apply to my business?
Triad charges are TNUoS charges based on demand during the three periods of highest national grid demand in winter. They apply to large half-hourly sites with demand above certain thresholds. Profile class 05-08 sites affected by P272 are not typically subject to Triad charges, but if your consumption is above 1 GWh per year, check with your supplier.
What is a Meter Operator Agreement?
A Meter Operator Agreement (MOA) is the contract between a business and an accredited Meter Operator (MOP) for the installation and ongoing maintenance of an electricity meter. For HH-metered sites, the MOP is separate from the supplier and charges for their services, usually via a passthrough on the electricity bill.
How we verified this
This article draws on published guidance from Ofgem, the Department for Energy Security and Net Zero, and the primary legislation and regulatory sources listed in the Sources section. No aggregator or supplier-produced content was used as a primary source.
