Half-hourly electricity meters can give businesses a much clearer picture of how and when they use energy.
For larger sites, high-usage businesses and multi-site portfolios, that data can be extremely useful. It can help identify usage peaks, improve budgeting, support procurement decisions and highlight areas where costs may be reduced.
However, half-hourly meters also come with more complexity.
Unlike a standard business electricity meter, a half-hourly meter can introduce additional contracts, extra invoice lines and network-driven charges that are easy to overlook if nobody is actively reviewing them.
For finance teams, this matters.
A half-hourly electricity contract is not just about the unit rate. Costs can also be affected by your agreed kVA capacity, Meter Operator contract, data services, DUoS charges, TNUoS exposure, reactive power and the timing of your site’s electricity demand.
If these areas are not reviewed properly, your business could be paying more than it needs to.
Who is this guide for?
This guide is mainly for finance directors, business owners, operations managers and anyone responsible for reviewing electricity costs across:
- Half-hourly electricity meters
- High-usage commercial sites
- Multi-site portfolios
- Manufacturing businesses
- Hotels, care homes and leisure sites
- Warehouses and distribution centres
- Sites with high peak demand
- Businesses with complex electricity invoices
The aim is to explain the main half-hourly cost areas in plain English, so you know what to check before agreeing to a new contract or accepting a renewal.
What is a half-hourly meter?
A half-hourly meter records electricity consumption in 30-minute periods.
Instead of relying on occasional manual reads or estimated usage, half-hourly data gives a more detailed view of when electricity is being used throughout the day and night.
This data is used for settlement, billing and network charging. It can also help businesses understand their usage pattern more accurately.
For example, half-hourly data can show:
- When your site reaches peak demand
- How much electricity is used during working hours
- Whether usage is high overnight
- Whether equipment is causing demand spikes
- Whether operational changes could reduce peak costs
- Whether your agreed capacity is set correctly
This makes half-hourly data useful, but it also means costs can become more sensitive to how and when your business uses electricity.
Why half-hourly meters can cost more if left unmanaged
Half-hourly meters are often associated with larger or more complex electricity supplies.
Because of this, the bill is usually more detailed than a standard business electricity bill.
Additional costs can include:
- Meter Operator charges
- Data Collection and Data Aggregation charges
- Availability or capacity charges
- Excess capacity charges
- Reactive power charges
- DUoS charges
- TNUoS-related costs
- Pass-through network and policy costs, depending on contract type
These costs are not always easy to spot.
A business may focus on the pence-per-kWh unit rate, while missing avoidable charges elsewhere on the bill.
This is why half-hourly meters should not be left on autopilot.
Managed properly, the data can help you reduce risk, improve budgeting and challenge unnecessary costs.
MOP, DC and DA contracts explained
With a half-hourly meter, there are additional metering and data services involved.
These are usually referred to as:
| Term |
What it means |
Why it matters |
| MOP |
Meter Operator |
Provides, maintains and supports the half-hourly meter. |
| DC |
Data Collector |
Collects and validates half-hourly consumption data. |
| DA |
Data Aggregator |
Aggregates and submits data for settlement. |
These services can be arranged separately or bundled into wider supply arrangements, depending on the supplier and contract structure.
The important point is that they should be reviewed properly.
Poorly managed MOP or data arrangements can lead to:
- Duplicate charges
- Poor data quality
- Estimated reads
- Delayed billing
- Rebilling issues
- Misaligned contract end dates
- Confusion over who is responsible for the meter and data
For finance teams, this can create unnecessary admin and make accruals harder to manage.
At WeSave, we help businesses review supply, MOP and data arrangements together, so the total cost and contract position are clearer.
What is kVA capacity?
kVA stands for kilovolt-ampere and is used to measure the agreed capacity available to your site.
For half-hourly electricity supplies, this is often referred to as your Maximum Import Capacity, or MIC.
Your MIC is the maximum level of electricity demand that has been agreed for your site with the local Distribution Network Operator.
In simple terms, it is the amount of electrical capacity reserved for your business.
You may see this appear on your bill as:
- kVA capacity
- Available capacity
- Authorised supply capacity
- Maximum Import Capacity
- Capacity charge
- Availability charge
This matters because many half-hourly sites pay a monthly charge based on the amount of capacity reserved, whether they use all of it or not.
Why kVA capacity should be reviewed
If your agreed capacity is too high, your business may be paying for capacity it does not need.
If your agreed capacity is too low, your business may face excess capacity charges if demand goes above the agreed limit.
That means both situations can cost money.
The aim is not simply to cut your kVA capacity as low as possible. The aim is to set it at a sensible level that reflects your actual demand, seasonal peaks, operational requirements and future plans.
For example, capacity may need to allow for:
- Seasonal trading peaks
- Commercial kitchens
- Refrigeration
- HVAC systems
- Lifts
- Manufacturing equipment
- EV charging
- Site expansion
- New machinery
- Future electrification plans
Reducing capacity too aggressively can create problems later if your site exceeds its agreed limit.
A proper capacity review should look at real half-hourly demand data, not guesswork.
A simple approach to reviewing kVA capacity
A sensible capacity review usually involves:
| Step |
What to check |
| 1 |
Review at least 12 months of half-hourly consumption data. |
| 2 |
Identify your maximum demand and regular peak demand. |
| 3 |
Compare actual demand against your agreed kVA capacity. |
| 4 |
Check whether you are paying for unused headroom. |
| 5 |
Check whether excess capacity charges have appeared. |
| 6 |
Allow for seasonal peaks, new equipment and future growth. |
| 7 |
Request a capacity change where appropriate. |
If your site has consistently used much less than its agreed capacity, there may be an opportunity to reduce the capacity charge.
If your site regularly exceeds the agreed capacity, it may need to be increased to avoid penalties and operational risk.
Reactive power and power factor charges
Reactive power is another cost that can appear on half-hourly electricity bills.
Without getting too technical, reactive power is linked to how efficiently electrical equipment uses power. If a site has poor power factor, the network may need to supply additional power that does not do useful work but still places demand on the system.
This can result in reactive power charges.
Common causes include:
- Large motors
- Refrigeration
- Pumps
- Compressors
- HVAC systems
- Older electrical equipment
- Poor or missing power factor correction
If reactive power charges appear regularly on your bill, it is worth investigating.
For some high-usage sites, power factor correction equipment can reduce or remove these charges and may provide a reasonable payback period.
DUoS and TNUoS charges explained
Half-hourly electricity bills can include network-related costs.
Two of the most common are DUoS and TNUoS.
What are DUoS charges?
DUoS stands for Distribution Use of System.
These charges recover the cost of using the local electricity distribution network.
DUoS charges can vary by:
- Region
- Meter type
- Voltage level
- Time of use
- Demand profile
For half-hourly meters, DUoS can be affected by when your business uses electricity.
In many cases, certain time periods are more expensive than others. These are often referred to as red, amber and green periods.
Red periods are usually the most expensive.
If your site has large demand peaks during red periods, your DUoS costs may be higher than necessary.
What are TNUoS charges?
TNUoS stands for Transmission Network Use of System.
These charges recover the cost of using the national electricity transmission system.
Depending on the type of contract you have, TNUoS-related costs may be included within a fixed unit rate or standing charge, or they may be passed through more explicitly.
Either way, demand patterns matter.
Businesses with high peak demand can be more exposed to network-related costs, particularly on more complex or pass-through contracts.
Fixed vs pass-through tariffs for half-hourly meters
Half-hourly electricity contracts can be structured in different ways.
Two common approaches are fixed tariffs and pass-through tariffs.
Fixed half-hourly electricity contracts
A fixed contract gives more budget certainty.
The supplier bundles many costs into a fixed unit rate and standing charge. This can make bills simpler to forecast and easier for finance teams to manage.
Fixed contracts are often suitable for businesses that want:
- Budget certainty
- Simpler invoices
- Less exposure to changing non-commodity costs
- Easier internal forecasting
For many businesses, this is the preferred route.
Pass-through half-hourly electricity contracts
A pass-through contract is more detailed.
Some costs may be fixed, while others are passed through at the rates that apply at the time. This can include network, policy and other non-commodity charges.
Pass-through contracts can suit businesses that:
- Have strong energy management processes
- Understand their usage profile
- Can shift demand away from expensive periods
- Want more visibility over cost components
- Have high usage or multiple sites
- Are comfortable managing more variable invoices
Pass-through can be useful, but it is not automatically cheaper.
It needs to be reviewed carefully against the site’s usage profile, risk appetite and budget requirements.
Common half-hourly billing issues to check
Half-hourly electricity bills can be complex, but there are some common red flags that finance teams can look for.
| Issue |
Why it matters |
| Capacity set too high |
You may be paying for unused kVA every month. |
| Capacity set too low |
You may face excess capacity charges. |
| Duplicate MOP charges |
You could be paying more than necessary for metering. |
| Reactive power charges |
Poor power factor may be adding avoidable costs. |
| Estimated HH data |
Billing may be less accurate than it should be. |
| High red-period DUoS costs |
Poorly timed usage peaks can increase total costs. |
| Misaligned contract dates |
Supply, MOP and data contracts may renew at different times. |
| Incorrect MPAN details |
Errors can create billing and tendering delays. |
These issues are often fixable, but they need to be identified first.
A regular half-hourly invoice review can help prevent small billing issues from becoming long-term costs.
Market-wide Half-Hourly Settlement and why data matters
The wider electricity market is also moving towards greater use of half-hourly data.
Market-wide Half-Hourly Settlement, often shortened to MHHS, is designed to settle electricity usage in half-hourly periods across a much wider part of the market. Elexon describes half-hourly settlement as measuring and settling electricity consumption at half-hour intervals, while the MHHS Programme says the reform is intended to support a more flexible and cost-effective electricity system.
This does not change the practical message for existing half-hourly sites today:
Accurate data matters.
The better your business understands its usage profile, capacity position and peak demand, the better placed it is to manage future electricity costs.
How finance teams can control half-hourly costs
A useful half-hourly review does not need to start with a complicated technical project.
It can start with a few practical checks:
| Area to review |
What to look for |
| kVA capacity |
Is your agreed capacity too high or too low? |
| MOP contract |
Are you paying a fair rate for meter services? |
| Data services |
Are reads accurate and being collected properly? |
| Reactive power |
Are regular charges appearing on invoices? |
| DUoS costs |
Are demand peaks falling in expensive time bands? |
| Contract type |
Is fixed or pass-through more suitable? |
| End dates |
Are supply, MOP and data contracts aligned? |
| Tendering |
Have supply and metering costs been reviewed together? |
The best results usually come from reviewing the whole position, not just one part of the bill.
How WeSave helps with half-hourly meter contracts
At WeSave, we help businesses review half-hourly electricity costs properly.
That means looking beyond the headline unit rate.
We can help review:
- Electricity supply prices
- Fixed and pass-through contract options
- kVA capacity charges
- Excess capacity charges
- MOP contracts
- Data contracts
- DUoS and network cost exposure
- Reactive power charges
- Contract end dates
- Multi-site tender opportunities
Where appropriate, we can compare supply, MOP and data services together so you can see the full picture clearly.
For businesses with multiple sites, we can also help align contract end dates, review usage profiles and tender sites together where this improves pricing or simplifies management.
Why the cheapest unit rate is not always the cheapest contract
With half-hourly meters, the cheapest-looking unit rate is not always the best deal.
A contract could have a competitive pence-per-kWh rate but still be expensive overall because of:
- High standing charges
- Expensive MOP fees
- Poorly structured pass-through costs
- Excess capacity charges
- Reactive power charges
- High red-period DUoS exposure
- Unclear non-commodity costs
- Misaligned contracts
This is why half-hourly electricity procurement needs to be reviewed as a full cost exercise.
The most important question is not simply:
“What is the unit rate?”
It is:
“What is the total expected cost of this contract based on our actual site profile?”
Quick decision path for finance teams
If you manage half-hourly meters, a simple review process could look like this:
- Pull your latest half-hourly electricity invoice.
- Check your agreed kVA capacity against actual demand.
- Look for any excess capacity or reactive power charges.
- Review MOP and data charges.
- Check whether any reads have been estimated.
- Compare DUoS exposure across time periods.
- Review whether fixed or pass-through pricing is more suitable.
- Check whether supply, MOP and data contracts have different end dates.
- Benchmark your renewal against current supplier prices.
- Tender the full position before agreeing to a new contract.
This does not need to be complicated, but it does need to be done before the renewal is agreed.
Quick FAQ
What is a half-hourly electricity meter?
A half-hourly meter records electricity usage every 30 minutes. This gives a detailed view of when electricity is used and is commonly used for larger or higher-demand business sites.
What is a MOP contract?
A MOP contract is a Meter Operator contract. The Meter Operator is responsible for providing, maintaining and supporting the half-hourly meter.
What are DC and DA charges?
DC stands for Data Collection and DA stands for Data Aggregation. These services collect, validate and submit half-hourly meter data for settlement and billing.
What is kVA capacity?
kVA capacity is the agreed electrical capacity available to your site. For half-hourly meters, this is often referred to as Maximum Import Capacity, or MIC.
Can reducing kVA capacity save money?
Yes, if your agreed capacity is higher than your site needs. However, reducing it too far can create excess capacity charges or operational issues, so it should be reviewed using actual half-hourly demand data.
What are DUoS charges?
DUoS stands for Distribution Use of System. These charges cover the cost of using the local electricity distribution network and can vary by time of use, region and demand profile.
What are reactive power charges?
Reactive power charges can appear where a site has poor power factor. They are often linked to equipment such as motors, refrigeration, compressors, pumps and HVAC systems.
Is a fixed or pass-through contract better for half-hourly meters?
It depends on the site. Fixed contracts usually provide more budget certainty, while pass-through contracts offer more visibility but can involve more cost movement. WeSave can compare both options where appropriate.
Compare your half-hourly electricity contract with WeSave
If your business has a half-hourly meter, it is worth reviewing more than just the unit rate.
Your kVA capacity, MOP contract, data charges, DUoS exposure and reactive power charges can all affect the total cost.
WeSave can review your half-hourly electricity position, compare available supplier options and explain the full cost clearly.
For a deeper look at specific half-hourly cost areas, you can also read our guides to half-hourly meter prices, half-hourly capacity charges, half-hourly MOP contracts and half-hourly pass-through charges.
To request a half-hourly electricity review, call 01872 495 111 or email hello@wesave.co.uk.