Half‑Hourly Electricity Meters: Why You Might Be Stuck With One — and What You Can Still Do to Save
Why Half‑Hourly (HH) Settlement Exists
Since 2017, Ofgem has required larger business electricity supplies to use Half-Hourly (HH) settlement — a system where your energy use is recorded every 30 minutes. This provides the grid with real-time usage data, helping to balance supply and demand more efficiently.
✅ The upside? More accurate billing and better network forecasting.
❌
The downside? Higher standing charges, more data management, and extra equipment — especially for low-usage businesses that don’t need heavy infrastructure.
The Two Types of HH Meters
Even though both are classed as HH meters, there are two distinct types, each with different cost implications:
🔌 Whole-Current (WC) HH Meter
Also known as a direct-connected meter.
- Fuse limit: Up to ~100 A per phase (~69 kVA total)
- No external current transformers
- Similar in appearance to a smart meter
- Suited to small-to-medium businesses with modest energy demand
⚙️ Current-Transformer (CT) HH Meter
Heavy-duty setup used for larger loads.
- For supplies over 100 A per phase
- Uses external CTs to measure current and a ratio (e.g. 200/5 A)
- Installed in a separate meter cabinet or CT chamber
- Can support loads in the hundreds of kVA
- Brings higher compliance, capacity, and maintenance charges
Typical Cost Stack for Each Type
| Cost Component | Whole‑Current HH (≤ 69 kVA) | CT HH (≥ 69 kVA) |
|---|---|---|
| DNO capacity charge | Usually none (profile‑class tariff) | £1–£2 per kVA / month (e.g. 150 kVA → ~£225 / mth) |
| Meter Operator (MOP) fee | Bundled with supply or ~£0–£100 / yr | £150–£250 / yr |
| HH Data Collector/Aggregator | N/A or bundled | £200–£400 / yr |
| Supplier standing charge | £0.60–£3 / day (can be slightly higher too) | £2–£4 / day (can be much higher) |
| Reactive power penalties | Rare | Possible if PF < 0.95 |
| Fixed‑cost ball‑park | ~£200–£500 / yr | £3 000–£4 500 / yr |
Paying four‑figure standing charges for a
site that uses less than a domestic house?
Book a free 15‑minute Capacity Review with our energy engineers
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🛑 Can You Downgrade from HH to Non-HH?
In short: No.
Several suppliers — including Crown Gas & Power and SSE — confirm that industry rules no longer allow downgrades from Half-Hourly (HH) to Non-Half-Hourly (NHH) metering.
⚠️ “It is not possible to downgrade a HH meter to NHH. The only option would be to disconnect your current service and lay a new NHH service.”
— Crown Gas & Power, June 2025
⚠️ “The industry rules don’t allow you to downgrade a half-hourly meter… Ofgem wants to move as many businesses as possible onto HH meters.”
— SSE Business Energy
So while you may come across outdated advice online about switching to a WC smart meter or downgrading from Class 00 to Class 03/04,
this is no longer permitted in practice.
🧠 But If You Can’t Downgrade… What Can You Do?
Even if you're stuck with a CT-configured HH supply, you don’t have to put up with inflated charges. Here’s how we help clients reduce costs:
📉 1. Review and Reduce Capacity (kVA)
If your business has scaled back — maybe you’ve downsized, closed a floor, or upgraded to low-energy equipment — you could still be paying for far more capacity than you use.
By reducing your Agreed Supply Capacity with the DNO (known as MIC or ASC), you can slash monthly charges. A capacity cut from 200 kVA to 69 kVA can save over £2,500/year on DUoS alone.
💼 2. Switch to a Supplier with Lower Fixed Costs
HH tariffs vary massively between suppliers.
Some charge minimal standing charges and offer bundled services for lower-usage CT clients — while others bolt on expensive MOP and data collector fees.
🔍 We compare prices from 28+ suppliers and help you find one that matches your usage and setup — not just your kVA.
📊 3. Request a Personalised Cost Review
We’ll analyse your HH data, review your current setup, and explore options to either cut costs or redesign your metering setup. If disconnection and reinstallation ever makes sense — we’ll walk you through it, including timeframes and costs.
🧾 What If You Really Want to Remove Your CT Meter?
If you still want to explore replacing your CT HH meter with a smaller WC smart meter, you’ll likely need:
- A full service disconnection
- New NHH supply cable installed by the DNO
- Metering reclassified and reinstalled by a supplier
It’s not cheap — but in some rare cases (e.g. closing production facilities or sub-letting the site), it might be worth it. We can help you assess the feasibility, risks, and total cost.
✅ Final Thoughts
Half-Hourly settlement is here to stay — but overpaying for oversized infrastructure doesn’t have to be. Whether it’s trimming your kVA, switching suppliers, or exploring a meter redesign, there are still plenty of ways to get control of your electricity costs.
🔍 Let’s review your setup.
A 15-minute check could unlock thousands in annual savings.
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