How do half-hourly meters work?

If you run a large business that uses lots of energy, you might need a half-hourly meter by law. But what exactly are half-hourly meters, how do they work and can they help you save on your business electricity bills?

Written by

Dan Tremain

Energy and business energy expert

Last Updated

27 JULY 2023

5 min read

What is a half-hourly electricity meter?

A half-hourly meter, also known as a HH or 00, is an electricity meter for businesses that sends automatic readings to your energy supplier every 30 minutes.

Both the older-style Advanced Meter Reading (AMR) devices and the newer smart meters can take half-hourly readings.

HH meters are a legal requirement for businesses that consume 100 kilowatts (kW) or more during any half-hour period. They’re mainly used by larger, energy-intensive businesses like factories, warehouses or large office complexes.

However, small businesses that have a maximum half-hourly demand of 70kW or more can also opt to have a HH meter installed.

Half-hourly meters explained

HH meters take a meter reading every half hour and automatically send the information to your supplier via a mobile signal or fixed phone line. As they’re fully automated and work remotely, there’s no need for you to take any manual readings.

Your supplier will receive up-to-date details of your business energy usage, so you can enjoy accurate bills instead of estimates.

Does my business need a half-hourly meter?

If your business has a peak demand of 100kW or more every half hour, you’ll have no option but to have a HH meter installed. Under the government strategy to reduce energy usage, all businesses must be offered the chance to have a smart meter installed by 2025.

If your business doesn’t have a smart meter yet, you should already be on an Advanced Meter Reading (AMR) device. This remote reading device also automatically sends readings to your supplier every half hour.

Although HH meters are mandatory for larger, energy-intensive companies, smaller businesses could also benefit from switching to a half-hourly tariff. Accurate readings mean you only pay for exactly what you use. It’s also a good way of monitoring your energy usage so you can take steps to increase your energy efficiency. Reducing your carbon footprint could also help cut the cost of your energy bills.

How are half-hourly meter charges different from normal billing?

Traditional electricity meters necessitate that you have to take manual readings and you could receive estimated bills. Half-hourly billing uses accurate, up-to-date readings of your energy usage. You’ll only be billed for the energy you use

What is a P272 mandatory meter change?

P272 is an Ofgem rule that’s been in force since April 2017. Under the regulation, energy suppliers are responsible for moving businesses with profile class 05-08 meters to 00 HH meters.

This means that non half-hourly meter readings are now settled as half-hourly.

P272 was introduced to make the energy market more efficient and create more accurate billing for business consumers.

Frequently asked questions

What is a DNO?

DNO stands for Distribution Network Operator. Your local DNO manages and maintains the electricity network for your area. They’re in charge of the cables and wires that deliver electricity from the National Grid to your business. They’re not the same as your electricity supplier.

If your business has a half-hourly meter, you must have an agreement with your local DNO about the maximum amount of power your premises can take from the National Grid. This will ensure they can supply you with enough power for your needs.

In turn, you’ll need to pay a charge based on your agreed maximum power load. This is called a Maximum Import Capacity (MIC), also known as Available Supply Capacity (ASC) or Authorised Supply Capacity.

What is an MOP?

MOP stands for meter operator.

An MOP is the company responsible for fitting your electricity meter and for its upkeep. If you have a half-hourly meter, you’re legally obliged to have an MOP agreement in place.

Prices and services can vary, and contracts can be as long as five years. It’s a good idea to shop around and compare quotes from a few MOPs before signing up.

What is a capacity charge?

The capacity charge, also called an availability charge, is what you’ll be charged by your local DNO. It’s charged monthly per unit (kilo-volt-amper - kVA) and covers maintenance of the electricity network.

What is a kVA charge?

This is another name for a capacity or availability charge. This covers the available power capacity provided to your business and is based on your Maximum Import Capacity (MIC).

The kVA charge is paid to the DNO indirectly via your energy supplier on a monthly basis. You can find your MIC and kVA charge on your energy bill or by calling your local DNO.