Half Hourly Meters: Understanding Capacity Charges

Electricity pilons
March 9, 2023
Min Read

Customers with Current Transformer (CT) Half Hourly Meters are subject to capacity charges.

A Capacity Charge is a fee you pay to ensure you are supplied with enough energy to meet your highest demand. The level of your Capacity Charge is agreed between you and your local Distribution Network Operator (DNO).

The threshold you set which determines your Capacity Charge is called a kVA Allowance.

Half Hourly Meters and Capacity Charges: The Background

Half hourly meter is designed for businesses that consume larger quantities of energy. They send a reading to your supplier every half an hour. This not only ensures your bills are accurate, it also helps to ensure the grid can cope with demand.

Based on your expected maximum usage, you will set your kVA allowance – and in turn, your capacity charge – at a certain level. This is agreed between you and your local DNO. The DNO then ‘reserves’ a certain amount of energy for you to use. The capacity charge will appear on your energy bill.

How to Avoid Excess Capacity Charges

If you exceed your agreed usage threshold in any billing cycle, you will notice an ‘Excess Capacity Charge’ on your bill.

To avoid an excess capacity charge, you have two options:

- Increase your kVA allowance, or

- Review your usage

If you are repeatedly exceeding your kVA allowance, you may want to increase your agreed capacity. This will raise your monthly capacity charge, but will reduce the risk of you repeatedly paying an excess.

Alternatively, you may be able to avoid exceeding your kVA allowance by preventing spikes in usage. This could involve staggering breaks or shift start times, or performing certain tasks overnight, such as charging forklifts and electric vehicles. Doing this is even more beneficial if you have a dual rate Half Hourly Meter, as it will enable you to make the most of the cheaper night rate.

Understanding your Usage

Half Hourly Meters are ideal for helping you to understand your usage, due to the frequency of readings they take. To determine where spikes in your usage are happening, you can request your half-hourly readings from your supplier. However, we offer our clients a much easier way to visualise their usage, via our Energy Management System.

This online dashboard shows you your half-hourly usage via easy-to-read graphs and charts. It’s available at no extra cost to all Tritility clients with Half Hourly Meters.

Is Your Capacity Charge Set Too High?

Reviewing your usage will also tell you if your kVA allowance has been set too high. If you are using significantly less energy than your agreed kVA capacity, your Capacity Charge could be higher than is necessary.

Example of a kVA allowance set too high

The above Half Hourly Meter usage data shows a kVA allowance that is set too high. Even at its highest, this customer’s usage peaks at 85kWH, while their kVA is set to 100kWH. In this situation, we would advise the client to reduce their Capacity Charge, cutting needless expenditure.

How to Get Help

If you need help understanding your Half Hourly Meter Capacity Charges, your supplier may be able to help. However, when you procure your energy through Tritility, our experts will be on hand throughout the duration of your fixed term to give advice and support.

We’ll give you full visibility of your half hourly usage as well as cost and carbon output. Understanding how you use energy will enable you to avoid usage spikes which could lead to an excess Capacity Charge. If we think yours is set too high or too low, we’ll quickly put it right.

To find out more about Half Hourly Meters, read our full guide here. To find out how much you could save on your energy, get a quote today.