UK Grid Operator Warns of Tighter Power Margins During Solar Eclipse

Britain's National Energy System Operator (NESO) issued a notice to the power market and generators on Wednesday, August 12, 2026 (21 Mordad 1405), according to Oilprice.com, to encourage actions to widen the system's safety margin between 18:00 and 20:00 local time that day, when a solar eclipse, coinciding with a widespread European heatwave and higher power demand, would block sunlight needed for solar generation. The estimated system margin shortfall for the period was put at about 1.2 gigawatts, against a current contingency requirement of 676 megawatts, with 1,000 megawatts of generation capacity also excluded from the available margin due to system constraints. The operator said the notice does not signal a risk of blackouts for customers, though a Maximum Generation Service instruction may be issued. Wednesday's total solar eclipse, Europe's first in three decades, was total across parts of Greenland, Iceland, Spain and Portugal and partial across most of Europe, including the UK, where up to 95% of the sun was obscured in Cornwall. Energy operators across Europe had prepared for a temporary drop in solar output during the event.