GB Grid Stability Digest
The week on the grid — 27 July – 2 August 2026
Issue 2026-w31
The system imbalance price peaked at £254/MWh in settlement period 38 on 2026-07-29.
Wind and solar peaked at 79.5% of GB generation at Wed 13:45 — the highest share in the 5 weeks the digest has tracked.
Wind and solar peaked at 79.5% of GB generation at Wed 13:45.
Vital signs
| This week | vs last week | |
|---|---|---|
| Inertia min / avg / max | 67.7 / 115.9 / 197.5 GVA·s | ▼ −0.1 GVA·s (min) |
| Frequency range (sampled) | 49.882–50.112 Hz · 152 samples beyond ±0.1 Hz | ▼ −0.128 Hz (min) |
| Peak wind + solar share | 79.5% (Wed 13:45) | ▲ +23.0 pp |
| Peak demand | 23.0 GW (Wed 01:15) | ▲ +0.9 GW |
| System price max / min | £254/MWh / −£14/MWh | ▲ +£34/MWh (max) |
Event of the week
The system price went negative in 5 settlement periods, bottoming at −£14/MWh.
Learn: Net-zero grid challenges
Decarbonising means replacing the heavy spinning plant that stabilised the grid for a century. Inertia is the quiet constraint on how fast that can happen.
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Data: Elexon BMRS · NESO · Carbon Intensity API · Sheffield Solar · All issues