On 12 August 2026, a total solar eclipse will track from Siberia across the Arctic, Greenland and Iceland to reach northern Spain and north-eastern Portugal, marking the first total solar eclipse over mainland Europe since 1999. Much of the rest of Europe will see a deep partial eclipse in the early evening, while parts of the eastern United States and Quebec will see a smaller partial eclipse around midday. Eclipse events are a challenging real-world test for balancing solar-powered grids, due to the uniform and wide-scale drop in irradiance across every solar asset. Markets with lots of behind-the-meter rooftop solar also see a ramp in load on the grid, that is correlated with the drop in renewables, potentially testing response and peaking capacity and storage dispatch.
Cloud cover will determine how much of the eclipse is actually visible from the ground, and the severity of the grid impacts. Current forecasts suggest better viewing conditions in Madrid, Paris and London, with cloud opacity generally remaining below 25% during the eclipse. Amsterdam and Berlin are more likely to experience greater cloud interference, with cloud opacity forecast for around 40% and 35% respectively. Reykjavik, despite lying within the path of totality, is forecast to experience much cloudier conditions, with cloud opacity of around 60-80% potentially obscuring the views of the eclipse event.
Across Europe, the eclipse occurs during the evening, with maximum eclipse occurring at approximately 17:48 local time in Reykjavik, 19:13 local time in London (BST), 20:17 in Paris, 20:10 in Amsterdam, 20:08 in Berlin and 20:32 in Madrid (all CEST). Because the sun will already be low in the western sky, visibility will also depend on having an unobstructed western horizon.
Counterintuitively, the largest daily irradiance losses are not expected beneath the deepest eclipse. Only around 1% of daily irradiance is expected to be lost across most of Spain, Portugal, France and the UK, because the eclipse there occurs late in the day, when the Sun is already low and contributing little to the day’s total. By comparison, Iceland is projected to lose close to 3% of daily irradiance and Greenland up to 6%, despite experiencing a less complete eclipse. As the impact on daily irradiance is a function of time of day, and depth of eclipse, the greatest impacts are felt further west of the eclipse path where the eclipse occurs earlier in the day
The same principle applies across North America. While only a partial eclipse will be visible across parts of the eastern United States and Quebec, the event occurs much closer to solar noon. As a result, New York is expected to lose around 2% of daily irradiance, while Quebec may see losses of 3% to 4%.
Solcast’s grid aggregation modelling shows that small daily irradiance losses can still create significant operational challenges for electricity networks. Germany, despite losing only around 1% of its daily irradiance, is projected to see both the largest total loss and the sharpest ramp of any region studied – an estimated 1,250 MWh lost and a maximum ramp rate of 13,150 MW/h as generation recovers. France is forecast to lose 540 MWh, with a 5,070 MW/h ramp.
The Netherlands and the UK are expected to lose a similar amount of energy overall (1,050 MWh and 920 MWh), but with very different ramp profiles: the Netherlands’ 6,120 MW/h maximum ramp is considerably steeper than the UK’s 3,800 MW/h.
Across North America, the impacts are smaller: ISO-NE is expected to lose 550 MWh with a 1,180 MW/h ramp, and NYISO 340 MWh with a 790 MW/h ramp. Europe’s steeper ramp rates stem directly from timing again: the eclipse-driven dip and the natural approach of sunset happen in close succession, forcing grids to absorb both within a short window.
Solcast produces these figures by tracking clouds and aerosols at 1-2km resolution globally, using satellite data and proprietary AI/ML algorithms. This data is used to drive irradiance models, enabling Solcast to calculate irradiance at high resolution, with typical bias of less than 2%, and also cloud-tracking forecasts. This data is used by more than 350 companies managing over 350 GW of solar assets globally.
The views and opinions expressed in this article are the author’s own, and do not necessarily reflect those held by pv magazine.
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