What happened

The National Energy System Operator (NESO) published its Outturn Balancing Costs report for 2025/26 and a2026 Thermal Constraints Update on 11 November 2026, as Lucy King reported for Energy Live News. The main figures:

  • Total: balancing costs rose 16% to £3.1bn in 2025/26. NESO says it and industry partners saved £891m that would otherwise have been spent.
  • Constraints: thermal constraints cost £2.0bn, 65% of the total and £250m more than the year before. Wind output was 17% higher, while network work cut capacity on the key Scottish boundaries to 57% of their maximum on average.
  • Gas fills the gap: about three quarters of the constraint cost linked to turning wind down was payment for replacement power, typically from gas plants.
  • Other costs: voltage support rose 23% to £366m and frequency response 36% to £267m; reserve fell 7% to £375m.
  • Outlook: NESO projects thermal constraint costs of £3.9bn in 2027 and between £6.8bn and £7.7bn in 2030 on its net zero pathways (in 2025 prices, before savings from planned initiatives), falling once major new transmission lines are built in the early 2030s.

What it means for your business

Balancing costs are recovered through the Balancing Services Use of System (BSUoS) charge, a fixed tariff per MWh that suppliers pass on to customers. NESO'slatest forecast shows the tariff at £12.49 per MWh from October 2026 to March 2027, and a draft tariff of £21.67 for April to September 2027, a rise of about 73%, then £18.42 from October 2027. Final tariffs are due in December.

Take an illustrative business using 200,000 kWh of electricity a year on a contract that passes BSUoS through at cost. At today's tariff that is about £2,498 a year. At the April 2027 draft rate it would be about £4,334 a year, and across April 2027 to March 2028 about £4,009. The carbon on the same electricity, using the 2026 government factor, is 26.19 tonnes CO2e (Scope 2, location-based), and that does not change with balancing costs: your reported figure uses the average UK factor for the year.

The bigger point is that a congested grid costs money and carbon at the same time. When wind in Scotland is turned down, gas plants in England are usually turned up to replace it. Until new lines are built, more of the clean power the UK pays for goes unused.

What to do now

  • Check your contract. Find out whether BSUoS and other non-energy costs are fixed in your price or passed through. If you are renewing before April 2027, ask your supplier or broker how the draft tariff is treated.
  • Budget for it. Multiply your yearly MWh by the tariff difference to see the likely change; the draft rate may still move in December.
  • Use less. Efficiency cuts both the BSUoS charge and your Scope 2 emissions, since both are charged per unit used.
  • Keep your meter data. Monthly kWh by site lets you show both the cost and carbon effect of any change.