GB Grid Stability Digest
The week on the grid — 29 June – 5 July 2026
Issue 2026-w27
System inertia ranged from 125.2 GVA·s to 161.6 GVA·s (average 138.6 GVA·s).
Demand peaked at 19.7 GW at Sun 08:15.
The system price averaged £90/MWh, peaking at £193/MWh.
Vital signs
| This week | vs last week | |
|---|---|---|
| Inertia min / avg / max | 125.2 / 138.6 / 161.6 GVA·s | — |
| Frequency range (sampled) | 50.097–50.097 Hz · none beyond ±0.1 Hz | — |
| Peak wind + solar share | 53.6% (Sun 15:00) | — |
| Peak demand | 19.7 GW (Sun 08:15) | — |
| System price max / min | £193/MWh / −£77/MWh | ▼ −£607/MWh (max) |
A quiet week
The system price went negative in 32 settlement periods, bottoming at −£77/MWh. Wind and solar peaked at 53.6% of GB generation at Sun 15:00. Nothing cleared the bar for an event — no frequency excursion beyond 50 ± 0.3 Hz, no system price above £300/MWh, no unplanned loss over 500 MW, no archive record.
Partial data coverage this week (17 of 168 hours) — coverage grows as snapshot history accumulates.
Worth reading
Learn: How wind power affects grid stability
Wind turbines connect through inverters, so they don’t naturally add inertia. High wind output means cheap, clean power — and a lighter, faster-moving grid.
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Data: Elexon BMRS · NESO · Carbon Intensity API · Sheffield Solar · All issues
Free to reuse with attribution (CC BY 4.0).