TNUoS

While DUoS covers your local network, TNUoS pays for the national transmission system - the network of high-voltage pylons and cables that transport electricity across Great Britain from power stations to regional networks. This is operated by the National Energy System Operator (NESO, formerly National Grid ESO).

TNUoS underwent major reform in April 2023 through the Targeted Charging Review (TCR). Previously, large businesses could reduce these charges through "Triad avoidance" - cutting usage during the three highest-demand half-hours each winter. Now, most businesses pay fixed charges based on capacity bands, removing the incentive (and complexity) of Triad management.

The charges vary by location across 14 zones - businesses in areas far from power generation typically pay more because electricity has to travel further, incurring more losses. These locational signals are designed to encourage new demand to locate nearer to power sources.

Key points:

• Set annually by National Grid ESO
• 14 demand zones (aligned with DNO regions)
• Post-TCR: ~88-100% recovered through fixed TDR bands
• Higher in areas far from generation (e.g., southern zones)
• Typically 5-10% of a business electricity bill