TNUoS charges: why HV connected sites pay more from 2026, and what to do

What changed in April 2026

Transmission Network Use of System (TNUoS) charges pay for the national grid. The largest part, the residual charge, is a fixed amount per site per day, recovered through your standing charge. From April 2026 it increased by roughly two thirds on average to fund grid reinforcement for clean power, and it is forecast to keep rising through to 2031.

Because it is charged per site rather than per unit, using less electricity does not reduce it. What decides your charge is the band your site falls into, set by its connection voltage and agreed capacity.

Why HV sites are most exposed

• Sites connected at high voltage (HV) sit in higher charging bands than low voltage (LV) sites, and the increases have been largest in the higher bands.
• The bands were reset in April 2026 and are locked for the five year price control. A site that has landed in a higher band will stay there until 2031 unless something changes physically.
• For a large HV site the difference between bands can run to tens of thousands of pounds a year, and for a portfolio of HV sites, considerably more over five years.

The options

• Check your band. First, confirm what band each site is in, on what basis, and whether the agreed capacity behind it is still right. Some sites are in a higher band than their real needs justify.
• Agreed capacity review. Where a site is carrying capacity it no longer uses, a formal reduction can move it to a lower band. This must be done carefully so supply is not put at risk.
• Metering relocation from HV to LV. For some sites, moving the point of metering from the high voltage side to the low voltage side changes the band the site is charged in. It is an infrastructure change, involving transformers and switchgear, and needs a feasibility study, design and build. On the right site it can remove most of the increase; on the wrong site it is not worth doing.
• On-site generation and flexibility. Reducing peak demand and capacity requirements over time can support a lower band at the next review.

What a proper feasibility study looks at

Relocating the metering from HV to LV lowers the TNUoS band, but it is not a free saving. Some costs move in the other direction, and a credible study nets them off before it recommends anything:

• Distribution charges rise. An LV metered site pays LV distribution rates, which are higher per unit than HV rates.
• Transformer losses become yours. Once the meter sits on the low voltage side, the electricity lost in the transformer is billed to you rather than absorbed upstream.
• Network operator costs and consent. The change usually needs a network operator or independent network operator to adopt the arrangement, with a technical submission, design and possibly new equipment.
• Physical works. Metering, current transformers, cabling and protection settings, with a survey and a technical pack before anything is priced firmly.

The output you should expect is a net figure over the price control period, an indicative payback, a clear recommendation to proceed, proceed with conditions, or not proceed, and a list of the information still needed. If a proposal only shows the TNUoS saving, ask what has been left out.

How Energy Planner helps

• Identify the band and the charge on each site from your bills and connection agreements.
• Model the options and what each is likely to save over the price control period.
• Manage capacity reviews with the network operator.
• Where relocation makes sense, bring in specialist engineering partners for feasibility, design and build, coordinated by us.
• Check the new charges appear correctly on your bills afterwards.

Common questions

Can I reduce TNUoS charges by using less electricity?
Not the residual part. It is a fixed charge per site per day based on your charging band, so it does not fall with consumption. The band itself is what you need to look at.

Can my site move to a lower charging band?
Sometimes. Bands are set by connection voltage and agreed capacity. Reducing capacity you no longer need, or changing where the site is metered, can change the band, but each needs assessing properly.

Is metering relocation right for every HV site?
No. It depends on the site's load, the existing equipment and the cost of the works against the saving over the price control period. A feasibility review comes first.

This page is general information based on published charging methodologies and forecasts as at September 2026, not advice on your specific sites. Charges, bands and forecasts change, and any physical works need a proper feasibility study, so it is worth confirming the position for your sites before making a decision.