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GB electricity market summary: Q3 2025

Renewables hit a Q3 record. What does it mean for prices, demand, and supply in Great Britain?

This report breaks down the key market movements between July and September. You will gain a comprehensive understanding of how renewables, fossil fuels, and imports have shaped supply, how prices have evolved, and what lies ahead for Q4. All based on real data, not projections.

What happened in Q3?

Q3 2025 saw the highest-ever level of renewable generation for a third quarter, led by strong wind and solar output. Wind generation rose 6% from the same period last year, despite frequent curtailments. Gas-fired generation stayed low, though not as low as the Q3 2024 record.

Summer temperatures softened demand, but cooling needs during heatwaves drove short-lived spikes in consumption and prices. Meanwhile, nuclear output hit a new low, and net imports continued to play a key balancing role.

The wholesale price environment remained relatively stable, but continued to reflect daily swings in weather and renewable availability.

Who should read this?

This summary is relevant if you’re involved in any part of the GB power market:

  • Energy traders can better understand day-ahead market behaviour and volatility triggers.

  • Utilities and suppliers gain insights on generation trends and pricing dynamics.

  • Renewable developers see how curtailments and negative prices impact revenues.

  • Policy and regulatory professionals get data-backed context on the energy mix and demand patterns.

European electricity market summary: Q3 2025

From negative prices to nuclear surprises - what shaped the EU power market this summer?
Download report

Key takeaways

  1. Renewables led the mix At 31.9 TWh, renewables (including biomass) made up just over half of total GB consumption. Wind contributed 17.7 TWh, solar 6.2 TWh, and biomass 7.0 TWh
  2. Curtailments remain high Wind curtailments averaged 1,051 MW per hour, peaking at 6.7 GW on 4 August - highlighting network constraints.
  3. Negative prices surged again EPEX recorded 104 half-hourly negative day-ahead prices 8 more than in Q3 2024. This triggered difference payment suspensions under CfD rules on 7 September.
  4. Gas prices dipped National Balancing Point (NBP) prices averaged GBP 27.26/MWh, down 3% year-on-year, moving in a see-saw pattern tied to renewables, maintenance, and geopolitical signals.
  5. Electricity prices rose Despite lower gas prices, day-ahead electricity averaged GBP 72.40/MWh, up from GBP 68.22/MWh in Q3 2024. Heatwaves and low renewables in July drove price peaks.

What to expect in Q4?

Looking ahead, wholesale prices are likely to remain stable but that could change quickly.

Early signs of La Niña suggest colder-than-normal weather this winter. If that plays out, demand may climb while renewables drop, leading to tighter margins and fewer negative price events.

Gas storage levels across Europe are healthy for now. But if demand surges, supply pressures could return fast especially if geopolitical risks escalate.

FAQ

  • Periods of low demand and high renewables, especially wind, drove prices below zero - even as heatwaves pushed up demand and average prices in other hours.
  • Yes. At 7.8 TWh, it was the lowest Q3 nuclear output since 2014 due to planned outages. Some plants are being extended, while Sizewell C construction has been approved.
  • France and Norway were the largest contributors, supplying 6.74 TWh and 2.10 TWh respectively.

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