Half-hourly vs non-half-hourly metering: the key differences
How does a half-hourly meter differ from a non-half-hourly one? Compare readings, settlement, charges and contracts side by side, and see which common myths about half-hourly metering are wrong.
Business electricity meters have traditionally fallen into two groups: half-hourly (HH) and non-half-hourly (NHH). The difference affects how your use is measured and settled, what appears on your bill and which contracts you need. This guide compares the two, corrects some common myths and explains how market-wide half-hourly settlement (MHHS) is changing the picture.
Key points
- HH meters record use in every 30-minute period; NHH meters record totals between reads.
- Sites with maximum demand over 100 kW in any half-hour must be HH metered.
- HH sites usually pay capacity, time-banded and reactive power charges.
- HH sites need metering and data services, often under separate contracts.
- MHHS is moving every meter in Great Britain to half-hourly settlement, with a full migration deadline of May 2027.
How each type of meter measures electricity
A half-hourly meter records consumption in each 30-minute settlement period: 48 readings a day and 17,520 a year (17,568 in a leap year). The data is collected remotely, usually daily, and your supplier is charged for what you actually used in each period. Our guide to what half-hourly metering is covers the basics.
A non-half-hourly meter records a running total, sometimes split into day and night registers. Readings are taken monthly, quarterly or less often, by a meter reader, a customer or a remote read. Under traditional NHH settlement, the market estimates when the electricity was used by applying a standard profile for the meter's profile class (01 to 08), rather than measuring it.
Side-by-side comparison
| Feature | Half-hourly (HH) | Non-half-hourly (NHH) |
|---|---|---|
| Readings | 48 a day, collected remotely | Periodic totals, sometimes day and night registers |
| Profile class on MPAN | 00 | 01 to 08 |
| Settlement | Actual use in each half-hour | Estimated from standard profiles (until migrated under MHHS) |
| When required | Maximum demand over 100 kW in any half-hour | Smaller sites below that threshold |
| Capacity charge | Yes, per kVA of Agreed Supply Capacity | Not usually |
| Network unit rates | Red, amber and green time bands | Usually single rate or day and night |
| Reactive power charges | Yes, when power factor is poor | Not usually |
| Metering and data services | Usually needed, often contracted separately | Usually arranged by the supplier |
| Data available to you | A detailed 30-minute profile | Limited to meter reads |
Why the charges look different
HH bills carry more lines because network charges for HH sites are site-specific. As well as the energy cost and policy costs, you will typically see DUoS unit rates in red, amber and green bands, a fixed daily charge, a capacity charge for your ASC, excess capacity charges if you go over it and reactive power charges if your power factor drops below about 0.95. Our guide on how to read a half-hourly bill explains each line.
NHH bills are usually simpler: a unit rate or day and night rates plus a standing charge, with network and policy costs built in.
Common myths about half-hourly metering
Myth: "Sites using over 100,000 kWh a year must be half-hourly"
The mandatory threshold is about demand, not annual consumption. A site must be HH metered if its maximum demand is over 100 kW in any half-hour. A site with short, sharp peaks can cross that line on modest annual use, while a site with a flat, steady load can use a lot of electricity without crossing it. Separately, the P272 rule change moved profile class 05 to 08 sites to HH settlement from April 2017. Our guide to the 100 kW rule goes into detail.
Myth: "Half-hourly always costs more"
HH bills have more charge lines and usually a metering contract, which can make them look more expensive. But HH pricing reflects when you actually use electricity. A site that uses most of its power overnight or at weekends, outside the red band, may be priced more favourably than a standard profile would suggest. Whether HH works out higher or lower depends on your load shape, capacity and contract, not the meter itself.
Myth: "A smart meter puts me on a half-hourly contract"
A smart meter can record half-hourly data, but that does not mean your site is billed like an advanced HH site with an ASC and capacity charges. Meter type, settlement and contract structure are separate things. Check your contract and the charges listed on your bill.
Myth: "Once I am half-hourly, metering looks after itself"
HH sites need a meter operator and data services, and these are often separate contracts with their own end dates. If one lapses without being renewed, charges can rise and data problems can lead to estimated bills. Keep a note of who provides each service and when the agreements end. Our metering and data services page explains the options.
How MHHS changes the picture
Market-wide Half-Hourly Settlement is Ofgem's programme, run by Elexon, to move every electricity meter in Great Britain, around 33 million, to half-hourly settlement. Suppliers began migrating meters on 22 October 2025, and the full migration deadline is May 2027.
MHHS is mainly a change to settlement, meaning how suppliers are charged for the electricity their customers use. It does not by itself turn a small site into one with an ASC and capacity charges. For existing HH sites the most visible change is to agent roles: the meter operator role for advanced meters becomes Metering Service Advanced (MSA), and data collection becomes the Advanced Data Service (ADS). Read more in our MHHS guide for businesses or on Elexon's MHHS pages.
Which applies to your site?
Five quick checks using your bill and meter data:
- Check the top line of your MPAN: profile class 00 indicates half-hourly metering.
- Look for a capacity charge or an ASC figure on your bill.
- Find your highest half-hour demand. If it is over 100 kW, HH metering is mandatory.
- Find out who your meter operator and data service are, and when those contracts end.
- Note your supply contract end date so you can review options in good time.
Get help with half-hourly metering
If you are unsure whether your site should be HH metered, or what your HH bill should include, we can check it for you and explain what we find.
Request a free quote or bill check or call 07565 147 170.
Frequently asked questions
Can I switch from a half-hourly meter back to non-half-hourly?
If your maximum demand is over 100 kW in any half-hour, half-hourly metering is mandatory, and sites moved under P272 cannot simply revert. With MHHS moving all meters to half-hourly settlement by May 2027, the old non-half-hourly arrangements are being phased out. The more useful question is whether your contract and capacity suit your profile.
Do half-hourly sites always need a separate meter operator contract?
Usually, yes. Larger half-hourly sites have traditionally appointed their own meter operator and data collector, roles that become Metering Service Advanced and the Advanced Data Service under MHHS. Some suppliers bundle these services into the supply contract. Check your bill and contract to see which applies, and note any separate end dates.
How can I tell whether my site is half-hourly?
Look at the top line of the MPAN on your bill. A profile class of 00 means the supply is half-hourly metered. Other signs include a capacity charge based on Agreed Supply Capacity, network charges split into red, amber and green bands, and charges for reactive power.
