GB Grid Stability Digest
The week on the grid — 3–9 August 2026
Issue 2026-w32
The system price went negative in 30 settlement periods, bottoming at −£48/MWh.
Wind and solar peaked at 78.6% of GB generation at Thu 15:45.
System inertia ranged from 103.9 GVA·s to 191.3 GVA·s (average 150.3 GVA·s).
Vital signs
| This week | vs last week | |
|---|---|---|
| Inertia min / avg / max | 103.9 / 150.3 / 191.3 GVA·s | ▼ −19.9 GVA·s (min) |
| Frequency range (sampled) | 49.827–50.179 Hz · 181 samples beyond ±0.1 Hz | ▼ −0.055 Hz (min) |
| Peak wind + solar share | 78.6% (Thu 15:45) | ▼ −0.9 pp |
| Peak demand | 26.0 GW (Fri 01:15) | ▲ +3.1 GW |
| System price max / min | £198/MWh / −£48/MWh | ▼ −£56/MWh (max) |
Event of the week
System inertia fell to 103.9 GVA·s at Thu 15:45 — the lowest weekly minimum in the 6 weeks the digest has tracked.
Worth reading
Learn: What is grid inertia?
Inertia is the grid’s stored rotational energy — its resistance to sudden frequency change. Less spinning metal means faster frequency swings when something trips.
Read the explainer →Get this in your inbox
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Data: Elexon BMRS · NESO · Carbon Intensity API · Sheffield Solar · All issues
Free to reuse with attribution (CC BY 4.0).