Energy suppliers are moving the electricity supply of every single business in Great Britain over to half-hourly settlement by 7 May 2027. The new Market-wide Half-Hourly Settlement (MHHS) may force your bills higher if you draw most of your electricity from the grid during expensive periods.
In this article, we explain the new system, how likely it is to affect your business and how your company can use commercial battery storage to protect itself from potential price increases.
What is half-hourly settlement?
Energy suppliers use half-hourly settlement to check whether they bought enough power for their customers in each 30-minute period.
If its customers use more electricity than the supplier bought, the supplier has to pay for the shortfall. If they use less, the supplier gets paid for the electricity it bought but didn’t need.
For people outside the electricity industry, this is confusing so here’s an explanation.
Say a supplier expects its customers to use 10,000 kWh between 2pm and 2.30pm, so it buys 10,000 kWh for that half hour.
If its customers actually use 10,500 kWh, the supplier is 500 kWh short and has to pay for the difference. If they only use 9,500 kWh, it has bought 500 kWh too much and is paid for that extra electricity through the settlement system.
A company called Elexon runs the settlement system in Great Britain and works out who owes what.
Your supplier doesn’t send you a separate bill for these half-hourly differences. What you pay still depends on your tariff.
So, why is this important to you? The new system makes it easier for suppliers to see when businesses use electricity. This may affect the tariffs they offer, and how much you pay, as they try to protect themselves from losses when customers use more electricity than expected at expensive times.
What is changing under the Market-wide Half-Hourly Settlement?
In Great Britain, many larger businesses already have half-hourly meters and are settled half-hourly, so very little will change for them. It’s the small businesses that will feel the effect the most because suppliers have often relied on estimates of when they used electricity, rather than actual meter readings.
Under the Market-wide Half-Hourly Settlement (MHHS) programme, suppliers will use actual 30-minute readings where they can. This gives them a much clearer picture of when each company actually uses electricity.
Sometimes there will be no actual meter reading for a particular half hour. When that happens, the supplier uses an estimate instead.
MHHS should make these estimates better. Instead of using the old standard patterns, suppliers use real half-hourly readings from smart and advanced meters to estimate the missing half hour. So even when an actual reading is missing, suppliers should have a better idea of when electricity was used.
The move to MHHS is not optional. Your supplier must move your electricity supply onto the new system by 7 May 2027. You do not apply for it, and you cannot choose to stay on the old settlement system.
Your supplier will tell you if your meter or metering arrangements need to change.
Here is the main dates in the MHHS timeline:
| Date | What happens | What it means for you |
|---|---|---|
| 28 October 2026 | All suppliers must be ready for MHHS. | Your supply does not necessarily move on this date. |
| 7 May 2027 | All electricity supplies must have moved to MHHS. | Your supplier may move yours before then. |
| 2 July 2027 | Final settlement is due to fall from 14 months to four months. | Suppliers will have less time to correct settlement figures. This does not change how often you are billed. |
Will MHHS make your electricity bill more expensive?
Not automatically. MHHS changes how suppliers record when you use electricity but it doesn’t set the prices on particular tariffs. For example, if you pay the same unit price all day, using more electricity at 2pm than 2am won’t change that unit price.
But if you are on a time of use tariff, you might be affected. On time of use tariffs, you pay one rate at one part of the day and another one at other times (sometimes there are more than two).
If a lot of your electricity use falls into the expensive periods, you could pay more. This is because more of the electricity you use is charged at the higher rate. Conversely, you could pay less if you draw more grid electricity in cheaper periods.
If your supplier contacts you with a new tariff that could cost more, ask them to show what it would have cost against your last 12 months of half-hourly electricity use before you agree to it.
What should you check with your supplier?
Before your supply moves to MHHS, ask your supplier four things:
- When will my supply move? It can happen any time before 7 May 2027.
- Are you getting actual half-hourly readings from my meter? If not, ask which periods are being estimated and whether anything needs fixing.
- How can I download my half-hourly data? A full year of readings will show when your business uses the most electricity and can be used for half-hourly data analysis.
- Will anything change when I move? Ask whether your tariff, charges, meter or metering service will change, and get any changes to what you pay in writing.
If you have more than one electricity supply, check each one separately. The Meter Point Administration Number (MPAN) on your bill tells the supplier which supply you are asking about.
Battery owners: protection against potential MHHS-driven price hikes
If your business already has a compatible battery, GridVolt can use your half-hourly data and tariff to work out when it should charge and when it should supply your site.
Energy Manager analyses current pricing, electricity use and, where applicable, expected solar generation, to charge and discharge your batteries to save the most money.
If your peak rates go higher after the change to MHHS, we can automatically adjust the battery schedule to reduce how much electricity you buy at those higher prices.
Fill in the form on the right to find out more, or get in touch via our contact page.
Half-hourly settlement FAQs
Does half-hourly settlement mean my electricity price changes every half hour?
No. Half-hourly settlement records how much electricity you use in each 30-minute period. Your tariff still decides what you pay and whether the price changes at different times of day.
Does the MHHS programme apply in Northern Ireland or the Republic of Ireland?
No. MHHS only applies in Great Britain. Northern Ireland and the Republic of Ireland use a separate electricity market called the Single Electricity Market.
Can my installer automatically access my half-hourly data?
No. Your installer does not automatically get access just because your supplier uses the data for settlement.
Ask your supplier how you can share the readings, or how to give your installer permission to access them. If you sign a letter of authority, check exactly what access you are giving.
Does profile class 00 still prove my supply is half-hourly settled?
No. Under the old system, profile class 00 showed that a supply was settled half-hourly. MHHS changes the information used to identify supplies, so profile class 00 is no longer a reliable way to check every migrated site. Ask your supplier to confirm the current settlement arrangements for your MPAN.
Does half-hourly settlement make your battery eligible for trading?
No. Half-hourly settlement on its own does not make a battery eligible for battery energy trading. A trading provider still needs to check your battery, meter, inverter, grid connection and contracts. In Great Britain, P415 allows independent providers to trade certain changes in how much electricity a customer uses.