How Suppliers Buy Electricity

Your Supplier purchases electricity from generation companies on your behalf. The Supplier is then charged by the National Transmission Network and Distribution Network Operators who deliver electricity to  your premises. The Supplier passes these charges to you – shown as TNUoS and DUoS charges (if they appear on your bill).

UK Energy Network 2

Distribution Use of System (DUoS) charges

What?
Recovers the cost of installing and maintaining the local distribution networks.

How?
Your charge is based on the volume of electricity, which has passed through the Distribution Network, that is consumed at site. Rates vary depending on your region, as well as the time of day, and are represented by a Red (Red Band), Amber, Green scale of charges.

Who?
Distribution Network Operators (DNOs).

Where?
You can identify which rates apply by finding the ‘Line Loss Factor’ for your site and looking it up on your DNO’s scale of charges.


Transmission Network Use of System (TNUoS) charges

What?
Recovers the cost of installing and maintaining the transmission system in England, Wales, Scotland and offshore.

How?
Your charge is based on your share of demand on the transmission network during its peak periods (Triads).

Who?
National Grid.

When?
Triad periods occur between 1st November and 28th February each year when demand on the National Grid is at its highest.