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DUoS & TNUoS Charges

In this guide, we look at what DUoS and TNUoS charges are and everything you need to know about them.

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Duos and TNUoS charges.

What Are DUoS & TNUoS Charges How They Are Calculated?

DUoS and TNUoS are electricity charges that apply to business energy users. How these charges are calculated has recently changed to help support the electricity network for future flexibility and to meet demand.

What is DUoS?

DUoS is an abbreviation for the Distribution Use of System. This is a charge that is added to all business electricity bills to cover the costs of the electricity distribution network. The DUoS charge is based on the amount of electricity consumed by your business.

The DUoS charge covers the cost of maintaining the local electricity distribution network infrastructure including the cables, substations, poles, and transformers.

The distribution network is responsible for delivering the energy from the National Grid transmission network to homes and businesses.

These networks are locally operated within eight regions by six operators. If you want to find out who your local distribution network operator visit the Energy Networks Association website.

The DUoS charges vary by region as each distribution network operator sets their charges within the price restrictions placed on them by Ofgem and regulates them.

These charges are time-banded for different times of the day depending on how much electricity is in demand in that period. These time bands encourage energy usage at times when the network is under less pressure from demand and discourage use at high-demand periods, such as between 4 pm-7 pm.

What is TNUoS?

TNUoS stands for Transmission Network Use of System. This is also an electricity charge that forms part of the business energy users’ electricity bill. The TNUoS is the charge for the electricity transmission network, also referred to as the National Grid, the charge applies to generators as well as business end users.

The charge pays for the cost of maintaining the electricity transmission network in England, Wales, Scotland, and offshore. This includes the cables, pylons, transformers, and other electricity infrastructure that transport the electricity at a high voltage between the electricity generators and the local distribution networks.

Recently the TNUoS charges have increased as the cost of the transmission network has risen due to the network requiring upgrades to replace its ageing infrastructure and to enable more renewable energy generation on the network.

The TNUoS charge is based on the share of demand on the transmission network during the triad periods.

The TNUoS charges are also banded like the DUoS but in triads which refer to periods of the year. The triad periods are between 1 November and 28 February when demand on the transmission network is at its highest. During triad periods the TNUoS charges are higher.

How to Reduce the DUoS and TNUoS Charges

The DUoS charges are banded by time bands with different rates per time band, for example, electricity used between 4 pm-7 pm Monday to Friday is the highest rate as that is when electricity has its highest demand.

Therefore, if you can adjust when you consume electricity according to these time-bands you could reduce your energy costs and assist the network in reducing demand at peak times.

TNUoS charges are linked to the time of year so if your business can use less electricity between 1 November to 28 February each year, you will be able to cut the cost of your energy bills.

In most businesses, this may prove difficult, but it is still worth knowing in case you can adjust your consumption patterns.

What is BSC Modification P272?

BSC Modification P272 came into effect on 1 April 2017 and it applies to half hourly meter customers who are in profile classes 5-8.

These customers must use their half-hourly consumption data from their advanced meters and not estimates so that energy suppliers can apply DUoS and TNUoS charges correctly for the periods.

P272 was set up to protect energy users by promoting value for money and helping to create a more sustainable energy network. It will foster competition by encouraging energy suppliers to create a wider range of energy offerings that are tailored to different energy needs.

It helps to encourage energy users to change their energy consumption patterns which assist the electricity network in meeting high demand periods and reduce the pressure during these periods.

P272 brought in a change in how businesses are charged for DUoS and TNUoS which has changed the cost of these charges and what businesses pay on their electricity bill. Some businesses will see their charges increase and others might see them reduce.  

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