Rising Fixed Charges on Import Power Supplies

What do the acronyms DUoS and TNUoS mean?

Guidance for renewable generators

Distribution Use of System (DUoS) and Transmission Network Use of System (TNUoS) are fixed charges, which are increasing from April 2024. These charges apply regardless of energy used and thereby impact unfairly on generators with relatively low import.

How much will DUOS & TNUOS increase by?

It depends on your apparent power

Optimised are here to help with guidance on what you need to know and how to mitigate impacts. On average, costs are increasing by £4,050 (for 100kVA supply) and £11,729 (for 500kVA supply).


In the table below, our experts present the current and new rates, and the costs incurred based on supplies with an available capacity of 100kVA and 500kVA.

 

kVA (Kilo-volt-amperes) is a measure of apparent power. This accounts for inefficient output where the kVA is below 100% and therefore less than kW (Kilo-watt) output.

How are energy exporters impacted?

Depending on your ENERGY contract

If you are on a fixed contract, this should not impact your costs until you renew, but if you are on a pass-through contract, you will see them on your April bill.

What are the next steps?

Optimised are experts on renewable generators

Fixed charges can be reduced if your site is non-final demand. Classification of a non-final demand site is listed below and if you believe you qualify, please get in touch to see how we can assist.


  • Have electricity generation
  • Only export electricity from your electricity generation or storage assets
  • Only import electricity to operate your generation and storage assets

Furthermore, Optimised can help prepare and mitigate impacts, by developing a strategy and tapping into our support packages to manage and reduce energy costs.

Custom Cost Mitigation Plans:

Tailored strategies to minimise the impact on your electricity bills. 

In-Depth Analysis:

We've crunched the numbers for you, to help you understand the specific changes in your area. 

Strategic Consultation:

Proactive measures to navigate and optimise your energy consumption.

Reach out for a consultation to safeguard your business from unexpected electricity cost hikes. Let's explore how we can tailor solutions to your unique needs.

RECENT NEWS

By Neil Fraser September 1, 2025
From 1 October 2025, the UK’s electricity balancing charge—known as the Balancing Services Use of System (BSUoS)—will rise significantly, with the tariff increasing from £10.74/MWh (1.074 p/kWh) to £15.69/MWh (1.569 p/kWh). The new rate will remain in place until 31 March 2026. This 46% increase will have a direct impact on businesses with pass-through energy contracts, as BSUoS costs are itemised separately on invoices and passed directly to end-users. For companies with substantial electricity consumption, the change will represent a noticeable uplift in costs. What is BSUoS? BSUoS stands for Balancing Services Use of System . It is a charge set by the UK’s National Energy System Operator (NESO) to recover the cost of keeping the electricity grid stable and secure. These costs cover activities such as: Adjusting generation when demand suddenly changes Managing supply during periods of constraint Maintaining system frequency and reliability Since April 2023, BSUoS has been recovered from final demand users through their suppliers. For businesses on pass-through contracts, this means the charge is shown transparently as a line item on invoices and fluctuates in line with NESO’s six-monthly tariff updates. The October 2025 Increase The next tariff change (Fixed Tariff 6) will see BSUoS rise by nearly half compared to the April–September 2025 level. For illustration: Period BSUoS Rate (p/kWh) Consumption (kWh) BSUoS Cost Change Apr–Sep 2025 1.074 1,400,000 £15,036 — Oct–Mar 2026 1.569 1,400,000 £21,966 +£6,930 For a business consuming 1.4 GWh over six months , this represents a cost increase of nearly £7,000 purely from BSUoS charges. Why the BSUoS Increase Matters for Corporate Buyers For organisations managing large or multi-site portfolios, the upcoming rise underscores the importance of understanding the components of pass-through contracts. While these contracts provide transparency and can offer cost advantages when markets fall, they also expose businesses directly to changes in regulated charges such as BSUoS. Key considerations include: Budget certainty : Forecasting for April 2025–March 2026 should include higher BSUoS costs. Procurement strategy : Weighing the pros and cons of fixed vs pass-through contracts depending on appetite for risk and transparency. Efficiency focus : Reducing overall consumption can help mitigate the impact of rising non-commodity costs like BSUoS. Looking Ahead: Forecasted BSUoS Rates for 2026 The October 2025 increase is part of the UK’s evolving energy cost landscape, with balancing costs expected to remain under pressure as the grid transitions to higher levels of renewables and flexibility services. NESO sets BSUoS tariffs twice a year, meaning further adjustments can be expected from April 2026. We will continue to keep you updated but at present, the forecasted rates f or April 2026 - October-2026 are: April 2026 to September 2026 – 1.455 p/kWh October 2026 to March 2027 – 1.103 p/kWh For corporate buyers, understanding these changes - and building them into procurement and risk management strategies - is essential to staying in control of energy budgets. References https://www.neso.energy/industry-information/charging/balancing-services-use-system-bsuos-charges?
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