TL;DR: Key Takeaways
- MHHS is migrating all UK business meters to half-hourly settlement by mid-2027. If you’re on a non-half-hourly meter (NHH - Profile Class 03 or 04), this change is coming whether you’re ready or not.
- Half-hourly meters carry up to 5 extra charge layers that NHH meters don’t have: MOP charges, DC/DA charges, capacity charges (CT meters only), restructured DUoS, and reformed TNUoS.
- Not every business faces every charge. The biggest cost - capacity charges - only applies to businesses with CT meters (larger connections that are already on half-hourly settlement). If you’re being migrated under MHHS, you almost certainly have a whole current meter and won’t face capacity charges.
- The charges you will definitely face are MOP (£150-£600/year) and DC/DA (£120-£300/year). That’s roughly £270-£900/year in new charges on top of your existing bill. (Based on a typical SME using around 25,000 kWh/year - your actual costs will vary by consumption, supplier, and provider.)
- You can reduce the impact by appointing your own MOP and DC/DA providers (rather than accepting supplier defaults), and by exploring time-of-use tariffs.
If you run a small or medium-sized business in the UK, your electricity meter is about to change. Not physically (in most cases) - but how it’s used to calculate your bill. MHHS itself doesn’t require a meter replacement - traditional meters can continue operating using profiled estimates. However, a separate DESNZ consultation (opens in new tab) proposes that from 1 January 2027, suppliers cannot offer new fixed-term contracts unless the business has (or agrees to have) a smart or advanced meter installed. So while MHHS is about settlement methodology, the smart meter rollout is pushing hardware upgrades through contract requirements.
Market-Wide Half-Hourly Settlement (MHHS) is an Ofgem-led programme that requires all UK electricity meters to be settled based on actual half-hourly consumption data. Previously, most SME meters were on non-half-hourly (NHH) settlement - your supplier assumed a typical usage pattern based on standard industry profiles and billed accordingly. Under MHHS, your supplier will know exactly how much electricity you used in every 30-minute window of every day. Your meter moves from NHH to half-hourly (HH) settlement.
The MHHS system went live on 22 September 2025 (opens in new tab), with suppliers beginning to migrate meter points from late 2025. Mass migration runs through 2026, with full completion targeted for mid-2027.
The headline benefit? More accurate billing. No more estimated reads, no more manually submitting meter readings, no more surprise catch-up bills. Ofgem estimates (opens in new tab) the programme will deliver £1.6 billion to £4.5 billion in benefits between 2021 and 2045.
What’s talked about less is the cost side. Moving from NHH to HH settlement introduces charges that most SME owners have never seen before. Here are the 5 you need to know about - what they are, whether they apply to you, and what you can do about them.
MOP Charges: The Meter Operator Fee You’re Probably Overpaying
Every half-hourly meter requires a licenced Meter Operator (MOP) - the company responsible for installing, maintaining, testing, and commissioning your metering equipment. NHH meters have MOPs too, but HH meter operators deal with more complex equipment, so they charge more.
Under MHHS, the MOP role is being renamed to MOA (Meter Operating Agent). Same job, new name.
Here’s how it works: when you get an HH meter, your supplier automatically appoints a MOP on your behalf. You don’t get asked. The MOP charges get bundled into your standing charge without being itemised - so most businesses have no idea what they’re paying for this service, or that they even have a choice.
How much do MOP charges cost on a half-hourly meter?
- Supplier-appointed default MOPs: typically £400-£600/year (opens in new tab)
- Independent MOPs: typically £150-£320/year (opens in new tab)
That’s a difference of up to £300/year - just by choosing your own provider instead of accepting the default.
Can you choose your own meter operator?
Yes. You can find accredited independent meter operators through the Association of Meter Operators (opens in new tab). The process involves choosing a provider, negotiating a contract (usually 3-5 years), and notifying your supplier of the change. Under BSC procedures, your supplier should process the appointment - this is a standard industry process that suppliers handle routinely, though individual supplier processes may vary.
Why suppliers don’t appoint the cheapest option for you: Because they don’t have to. Supplier-appointed MOPs often involve preferred provider arrangements where the supplier gets a rebate or margin. The cost difference is buried in your standing charge, so there’s no competitive pressure to find you a better deal. It’s the same problem we see across the energy market - opacity benefits the intermediary, not the customer.
DC/DA Data Charges: Paying for Your Meter to Be Read
Half-hourly meters generate 17,520 data points per year (48 half-hours x 365 days). That data needs to be collected, validated, and submitted into the national settlement system. Two separate licenced roles handle this:
- Data Collector (DC): Reads your meter remotely every half hour, validates the data, and checks it for errors
- Data Aggregator (DA): Combines your half-hourly data with data from other sites and submits it to Elexon for settlement
NHH meters don’t have separate DC/DA charges. Their reads are either collected automatically via AMR (Automatic Meter Reading - where the meter sends readings via GPRS or 3G without anyone visiting) or estimated using standard industry profiles. With estimated reads, your supplier assumes a typical usage pattern and bills you based on that. The problem? If your actual usage doesn’t match the estimate, you either get a catch-up bill (if you used more than estimated) or a reconciliation credit (if you used less). These adjustments can arrive months later, making budgeting unpredictable. Suppliers do request actual meter readings at certain points in the year to keep estimates in range - but the gap between estimated and actual usage is a constant source of billing disputes.
MHHS fixes this. With half-hourly data flowing automatically from your meter, your supplier knows exactly what you used and when. No more estimates, no more surprise catch-up bills months later. Billing accuracy improves significantly - which is genuinely good for budget certainty, even if it comes with the additional cost layers we’re describing here.
Under MHHS, DC/DA roles are being restructured into SDS (Smart Data Services) for smart meters and ADS (Advanced Data Services) for advanced meters.
How much do DC/DA data charges cost?
DC/DA charges are usually bundled into your standing charge, which makes them hard to isolate. Based on industry sources (opens in new tab), combined DC/DA fees typically run £120-£300/year depending on the provider and whether you accept supplier defaults or appoint independently.
How to appoint your own DC/DA: Just like with MOPs, you have the right to choose your own DC and DA rather than accepting the supplier’s default. You can find accredited providers through the BSC (Balancing and Settlement Code) framework. The process is similar - choose a provider, agree terms, and notify your supplier. Independent DC/DA providers are typically cheaper than supplier defaults, though the exact saving varies by provider and contract terms.
Why this matters: MOP + DC/DA combined could cost your business £270-£900/year. Every HH meter has these charges. If you’re a small business using 25,000 kWh per year, even at the lower end that’s adding about 1.1p/kWh to your effective electricity rate - and at the higher end (accepting supplier defaults), it’s 3.6p/kWh. For context, that’s equivalent to a broker commission sitting on top of your bill that you never agreed to.
Capacity Charges (kVA): The Big One - But It Probably Doesn’t Apply to You
This is the charge that sounds the scariest - but here’s the critical detail that most guides miss: capacity charges only apply to businesses with CT meters (current transformer meters). And if you have a CT meter, you’re already on half-hourly settlement. MHHS migration doesn’t give you a CT meter - if you’re being migrated, you almost certainly have a whole current meter.
What’s the difference between a CT meter and a whole current meter?
Think of it like the water supply to a building. A house has a standard pipe coming in from the mains - it handles normal domestic flow and nobody asks you to pay for the size of the pipe. That’s a whole current meter. The electricity passes straight through it, it measures what you use, and that’s it. Most small businesses - shops, offices, cafés, salons - have this type.
But a warehouse, factory, or large office block needs a much bigger supply. The electrical current flowing in is too strong for a standard meter to measure directly, so it uses current transformers (CTs) - devices that step the current down to a level the meter can read (opens in new tab). That’s a CT meter. Because you’re drawing from a bigger chunk of the network, your local Distribution Network Operator (DNO) sets an agreed Maximum Import Capacity (MIC) - the maximum amount of power (measured in kVA) your premises can pull at any moment. Think of it like reserving lanes on a motorway - you pay a fixed daily charge for that reserved capacity whether you use it or not.
Why this isn’t an MHHS issue: Businesses with CT meters are on Profile Class 00 - they’re already on half-hourly settlement and have been for years. The businesses being migrated under MHHS are on Profile Class 03 and 04 - and these are whole current meter connections. So if MHHS is the reason you’re reading this article, capacity charges almost certainly don’t apply to you. We’re including them here for completeness, and because it’s important to understand the full picture of HH meter charges.
How to tell which one you have: If your business runs off a standard supply - the kind you’d find in a high street shop or small office - you have a whole current meter (opens in new tab). No MIC, no capacity charges. If you’re in a larger unit with three-phase power and a meter cupboard full of equipment, you likely have a CT meter - and you’re probably already on HH settlement. You can also check your bill - if you see a line for “availability charges” or “capacity charges”, you have a CT meter.
What it costs (for businesses that do have CT meters):
Capacity charge rates vary by DNO region. Based on real data from our THIS Workspace case study, a flexible office provider in Bournemouth was quoted 9.67p/kVA/day by Tem Energy. Rates vary depending on your region and voltage level - some DNO regions charge more, some less. For more on how kVA and capacity charges work (including the motorway lane analogy), see our guide to business electricity standing charges.
For a business with a 40 kVA connection at 9.67p/kVA/day, that’s about £1,412/year in capacity charges. For a 100 kVA connection at the same rate, it’s £3,530/year. These are significant costs - but they only apply to CT meter connections that are already on HH settlement.
Excess capacity charges can make it worse. If your actual demand exceeds your agreed MIC at any point, the excess is charged at a penalty rate that’s significantly higher than the standard rate (opens in new tab).
The opportunity: If your business has downsized, removed equipment, or improved efficiency since your MIC was originally set, you may be paying for capacity you don’t need. Requesting a kVA review from your DNO can significantly reduce these charges. In our THIS Workspace case study, the previous supplier had quoted 32.94p/kVA/day - more than triple what Tem Energy quoted for the same 40 kVA connection.
One business owner reported on MoneySavingExpert (opens in new tab) paying a £12/day standing charge on an HH meter for a site using just 1,300 kWh per year. At that consumption level, the fixed charges massively outweigh the energy cost itself.
DUoS Charges: How Network Costs Change on HH Meters
Distribution Use of System (DUoS) charges exist on both NHH and HH meters - you’re paying for the local distribution network either way. But the structure changes when you move to HH settlement.
On an NHH meter, DUoS is simple: a flat p/kWh rate plus a daily standing charge. Straightforward, predictable, and easy to understand on your bill.
On an HH meter, DUoS splits into time-of-use bands (red/amber/green periods with different rates depending on when you use electricity). If you also have a CT meter with an agreed capacity, DUoS includes a kVA-based component too.
The difference between NHH and HH DUoS varies significantly across the 14 DNO regions in Great Britain. The impact depends on your region, your consumption pattern, and whether you have a CT meter. For businesses that can shift usage away from red-band periods (typically 4pm-7pm on weekdays in winter), the time-of-use structure could actually reduce DUoS costs compared to the old flat rate.
Important context: Much of the DUoS difference is driven by the capacity component - which only applies to CT meters. If you have a whole current meter (and if you’re being migrated under MHHS, you do), the DUoS restructuring is less dramatic. You’ll move from a flat rate to time-of-use bands, but you won’t pick up the capacity element.
TNUoS Charges: The Big Pylons Explained
Transmission Network Use of System (TNUoS) charges pay for the national high-voltage transmission network - the big metal pylons you see when you drive along the motorway. This is the infrastructure that carries electricity across the country from power stations and wind farms before it reaches your local distribution network. Think of it as the motorway system for electricity, while DUoS covers the local roads.
Many guides about HH meters describe the old Triad-based charging system as if it still fully applies. It doesn’t. The rules changed in April 2023, and those changes specifically protect businesses like yours from the old HH-style TNUoS costs.
What changed: Ofgem’s Targeted Charging Review (TCR) (opens in new tab) reformed how TNUoS demand charges work. Before the TCR, HH-metered businesses were charged based on their usage during the three highest demand half-hours each winter (called Triads). This was unpredictable and could be expensive. The TCR moved 80-90% of those charges to fixed bands based on your connection size - so you know what you’ll pay upfront, regardless of when you use electricity.
On top of that, CMP266 (opens in new tab) specifically prevents businesses migrating from NHH to HH settlement from facing the old HH-style TNUoS demand charges. This was designed precisely to make sure MHHS migration doesn’t land SMEs with surprise TNUoS costs.
What this means for your business: If you’re moving from NHH to HH under MHHS, TNUoS charges will shift from a flat p/kWh charge bundled into your unit rate to a fixed capacity band. In cost terms, this is broadly similar - it’s a restructuring of how the charge appears on your bill rather than a big increase.
Total TNUoS charges across GB were £5.3 billion in 2025/26 and are forecast to reach £6.2 billion in 2026/27 (opens in new tab) - a £1 billion increase driven by rising network investment costs. But this increase affects all customers equally, not just HH meters.
Regional note: TNUoS charges are locational. Businesses in northern England and Scotland generally pay lower TNUoS rates than those in the south, because they’re closer to major generation assets. NESO publishes the tariffs annually (opens in new tab). For more on how location affects your energy costs, see our guide to regional business energy prices.
What This Actually Costs: A Real-World Example
How much extra does a half-hourly meter cost per year?
Let’s work through what these charges mean for a real business. We’ll use a 25,000 kWh/year business - a typical small office, retail unit, or café - with a whole current meter (no CT meter, no capacity charges). This is what most businesses being migrated under MHHS look like.
| Charge | NHH Meter | HH Meter | Annual Difference |
|---|---|---|---|
| MOP (Meter Operator) | ~£100/year (bundled) | £150-£600/year | +£50-£500 |
| DC/DA (Data Collection) | ~£0 (bundled/minimal) | £120-£300/year | +£120-£300 |
| DUoS (restructured) | Flat rate | Time-of-use bands | Varies by region and usage pattern |
| TNUoS (reformed) | Flat p/kWh (bundled) | Fixed capacity band | Broadly similar post-TCR |
| Total additional charges | ~£170-£800/year |
Note: This is for a whole current meter without capacity charges, based on a 25,000 kWh/year business. “Supplier default” means your supplier appoints the MOP and DC/DA for you (top end of the range). “Independent providers” means you shop around (lower end). DUoS and TNUoS differences vary by region - they’re structural changes rather than straightforward cost additions.
For a 25,000 kWh business:
- Best case (independent MOP + DC/DA): roughly +0.7p/kWh in additional charges
- Worst case (accepting all supplier defaults): roughly +3.2p/kWh in additional charges
That’s a meaningful difference. For context, competitive fixed electricity rates for SMEs are currently around 22-24p/kWh (as of February 2026). Adding 3.2p/kWh in HH charges is a 13-15% increase on your effective rate - just from accepting supplier defaults you didn’t know you could change.
How these charges appear on your bill: MOP and DC/DA won’t change your unit rate - you’ll still see 23p/kWh (or whatever your contracted rate is) on the unit rate line. Instead, these charges get added to your standing charge or appear as separate daily line items. Your unit rate stays the same, but your daily fixed costs go up. We express the impact as “effective p/kWh” throughout this article because it’s the clearest way to show the real cost relative to your consumption - but on your actual bill, it’s your standing charge that takes the hit.
If you already have a CT meter, the picture is different. Capacity charges of 2-10p/kVA/day on top of MOP and DC/DA can push total additional costs to £1,500-£3,500+/year depending on your connection size and DNO region. But these businesses are already on HH settlement - this isn’t a new cost from MHHS migration.
The Upside: Why HH Metering Isn’t All Bad News
This isn’t all doom and gloom. There are genuine reasons Ofgem is pushing this reform, and some businesses will benefit:
More accurate billing. No more estimated reads, no more manually submitting meter readings, no more surprise catch-up adjustments. You pay for exactly what you used, when you used it. If your actual consumption pattern is different from the assumed profile your supplier was using, you might end up paying less. This is the same transparency principle we talk about with broker commission disclosure - when you can see the real numbers, you can make better decisions.
Time-of-use savings. If your business can shift consumption to off-peak periods (overnight, weekends, early morning), time-of-use tariffs become available. A bakery starting at 4am pays less than a restaurant firing up ovens at 6pm - even if both use the same total kWh.
Demand-side response revenue. Half-hourly data is a prerequisite for participating in flexibility markets - where you get paid to reduce or shift consumption during peak periods. For businesses with flexible loads (EV chargers, HVAC, refrigeration), this can generate genuine revenue.
Better load shape visibility. Half-hourly data shows exactly when you’re using electricity and how much. This makes it easier to spot waste, optimise operations, and challenge your supplier if their charges don’t look right.
The catch is that these benefits disproportionately favour larger businesses with energy managers, automated systems, and the scale to justify demand-side strategies. A small shop has limited ability to shift its usage to 3am. But the MOP and DC/DA savings from appointing independent providers? That’s available to everyone.
How to Manage Your Half-Hourly Meter Charges: 6 Steps
1. Check your meter type. Look at the first two digits of your MPAN (on your electricity bill). Profile Class 03 or 04 means you’re on NHH and will be migrated. Profile Class 00 means you’re already HH. Then find out whether you have a CT meter or a whole current meter - this determines which charges apply to you.
2. Ask your supplier about your migration timeline. Suppliers are migrating customers in phases. Find out when your meter is scheduled to move to HH settlement so you’re not caught off guard. Consultus has a useful overview (opens in new tab) of what to expect from the MHHS transition.
3. Request itemised billing. Once on HH settlement, ask your supplier to break out MOP, DC/DA, and (if applicable) capacity charges separately. If they’re bundled into your standing charge, you can’t tell whether you’re overpaying. This is the same principle behind Ofgem’s push for commission disclosure - transparency is the first step to managing costs.
4. Appoint your own MOP and DC/DA. This is the single biggest thing you can do. You don’t have to accept the supplier’s defaults. Get quotes from independent providers through the Association of Meter Operators (opens in new tab) for MOPs and accredited DC/DA providers through the BSC framework. Switching from supplier defaults to independent providers can significantly reduce these charges.
5. Review your capacity charges (if you have a CT meter). There are two separate ways to reduce capacity costs. First, contact your DNO to review your agreed MIC - if your business has downsized or improved efficiency, your actual peak demand may be lower than your agreed capacity. Reducing your MIC from, say, 100 kVA to 40 kVA means you pay capacity charges on fewer kVA. Second, the p/kVA/day rate itself varies by supplier. In our THIS Workspace case study, the previous supplier quoted 32.94p/kVA/day while Tem Energy quoted 9.67p/kVA/day for the same 40 kVA connection - so shopping around on supplier rates matters too.
6. Check your contract for HH settlement provisions. Does your current contract account for these charges? Many older contracts priced for NHH billing don’t include provisions for the additional HH cost layers. If your renewal is coming up, make sure the new contract reflects the HH charging structure. Our guide on business energy contract red flags covers the key clauses to watch for - including pass-through charges and volume tolerance traps that become more relevant under HH settlement.
What This Means for Your Business
MHHS is part of a broader shift in how the UK energy market works. Non-commodity charges - network costs, policy costs, and levies - now make up roughly 60% of a typical business electricity bill (opens in new tab). With MHHS, many of these charges become more visible and more granular. That’s good for transparency. But it also means more complexity to navigate.
The key takeaway: not all HH charges are equal, and not all businesses face the same charges. If you have a whole current meter (most small businesses, and all businesses being migrated under MHHS), your additional HH charges are primarily MOP and DC/DA - and you can reduce those by appointing independent providers. If you already have a CT meter and are on HH settlement, capacity charges are the big one - and those are worth reviewing with your DNO.
The businesses that benefit most from MHHS will be those that understand which charges apply to them, take control of their appointments, and use the improved data visibility to optimise their usage. The ones that get stung will be those who accept every default and never look at the detail.
Sound familiar? It’s the same dynamic we see with broker commissions, deemed rates, and contract red flags. In energy, the businesses that pay the most are usually the ones that know the least about what they’re paying for.
If you’re unsure how MHHS will affect your specific business, request a free analysis and we’ll break down exactly what these changes mean for your bill.
Further Reading
- Understand your current bill: 7 Red Flags in Business Energy Contracts - including pass-through clauses that become more relevant under HH settlement
- Standing charges & capacity: Business Electricity Standing Charges UK Guide - including how kVA capacity charges work and the motorway lane analogy
- The cost pressure on SMEs: The SME Energy Triple Whammy - prices, brokers, and transparency
- Regional differences: Regional Business Energy Prices UK - why DUoS and TNUoS vary by location
- Broker transparency: The TPI Code and Energy Broker Transparency - how commission disclosure is changing the market
- What a broker letter means: What is a Letter of Authority? - know your rights before signing anything
For official guidance, Ofgem’s MHHS decision and full business case (opens in new tab) sets out the regulatory framework and expected benefits. NESO publishes TNUoS tariffs annually (opens in new tab) if you want to check regional transmission charges.
Important: The charge ranges in this article are based on publicly available industry data and sources cited throughout. Actual charges vary significantly by DNO region, supplier, connection size, and meter type. MHHS timelines are subject to change - Ofgem has revised the programme schedule multiple times since the original 2021 decision. Always confirm specific charges with your supplier or DNO.
Sources: MOP cost ranges from Perfect Clarity (opens in new tab) and Touchstone Services (opens in new tab). DC/DA cost ranges from industry sources including Touchstone Services (opens in new tab). Capacity charge data from Perfect Clarity (opens in new tab) and Meet George case study data. MOP appointment process from Association of Meter Operators (opens in new tab). BSC framework from Elexon (opens in new tab). CT meter vs whole current meter from GoSwitchgear (opens in new tab). TCR reform from Energy Industries Council (opens in new tab). CMP266 from Ofgem (opens in new tab). TNUoS tariff data from NESO (opens in new tab). Non-commodity charge percentage from Cornwall Insight (opens in new tab). MHHS programme details from Ofgem (opens in new tab).