Transmission Network Use of System

What Are TNUoS Charges?

TNUoS (Transmission Network Use of System) charges are levied by the UK’s electricity transmission network operators for the operation, maintenance and development of the UK’s national transmission networks.

For half-hourly customers, TNUoS is billed using Triads, the three half-hour periods during winter where the demand on the UK’s transmission network is at its highest. The charges are calculated on a £/kW basis in April every year, using your average maximum demand across the three Triad periods.

That means that the more power you consume during the Triad periods, the higher your TNUoS costs will be. Conversely, if you reduce your load during these periods, you can cut your TNUoS costs significantly.

How Can I Reduce My TNUoS Charges?

Load management, if used correctly, can completely eliminate TNUoS charges, particularly if you are able to switch to on-site generation for short periods of time over the winter period – however you need to be sure that this benefit will be passed through to you by your supplier. Contact us to find out how you can effectively avoid Triads using effective load management.

Billing errors are common within TNUoS charges, due to the complexity of the charging mechanism and the typical supplier methodology of splitting the charges into monthly instalments with annual Triad reconciliations. Contact us to carry out a full audit of your historical TNUoS costs and Triad reconciliations.