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DUoS Charges

What are DUoS charges?

What is DNO?

Distribution Network Operators (DNOs) are licensed companies that own and operate a network of cables, transformers and towers that bring electricity from the national transmission network to businesses and homes. 

To find out who your Network Provider is, you can visit the Energy Networks Association website and search via your Postcode. 

There are a few third-party charges, also known as non-commodity charges, which are applied by DNOs. They are associated with delivering electricity from the source of generation to the end user via networks. These charges, if applicable to you, will be part of your overall electricity bill.   

DUoS cover the cost of operating and maintaining a safe and reliable electricity infrastructure between the transmission system and end users such as homes and businesses.  

All DUoS charges are set by DNOs.  

DUoS (Distribution Use of System) charges may consist of:  

  • Availability charge – Also known as KVA and Agreed Supply Capacity (ASC) charge. This is the charge for the power capacity held available for a supply point. It is charged in £/kVa/day whether you use it or not. 
  • Excess availability charge – Is charged if the Agreed Supply Capacity is exceeded. If the capacity is breached and excess power is used, this is chargeable as an excess availability capacity charge. It’s important that you set your kVA at the correct level, so you do not pay for capacity that you don’t need. You can contact your local DNO directly to discuss your kVA requirements.
  • Reactive power – Reactive power is a measure of “non-working” power. Some electrical equipment, typically motors and transformers, require reactive power to function effectively. Reactive power is chargeable if it exceeds limits set by the DNO. If your site has a poor power factor (ratio of active power to reactive power), it is possible to mitigate these costs by installing Power Factor Correction equipment.
  • Daily charge or Standing charge – This is a charge set by your supplier which must be paid, regardless of your energy usage. This covers the cost involved in distributing and supplying energy to you, as well as maintaining the infrastructure required to do this.
  • Unit rates – There are three-time band periods in which these rates are split into; Red, Amber and Green. We use the time banding that is created by the regional distribution companies. These will differ depending upon the company supplying that region.

Depending on the meter type and the product supplied some or all of these charges will be payable. 


DUoS Tips

The scale and time-bandings of DUoS charges can vary from region to region, but the red scale of charges is applied to the electricity used at ‘peak’ times where there is the most demand; between 16:00-19:00, Monday to Friday. 

 This is the highest charged period for DUoS. If you want to pay lower DUoS charges, you can try to use less electricity during peak times. 


TNUoS cover the cost of installing and maintaining the electricity transmission system in the UK. It is a non-commodity charge which will be reflected on your electricity bills if applicable to your business. 

Customers pay a charge based on their location and generation demand. TNUoS is calculated during the four-month winter period from November-February each year, when the National Grid’s demand is at its highest. This is known as the ‘Triad Period’. 

If you can use your energy strategically during the triad period, you will be able to pay a lower TNUoS charge. 

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