By Jonathan Simon, Product Manager at enercast

On 12 August 2026, a solar eclipse will occur across large parts of Europe. For solar power plant operators, grid operators, direct sellers and energy traders, the question arises: how will this event affect photovoltaic generation? And how is this effect considered in the enercast solar generation forecast?

Source: NASA/GSFC Scientific Visualization Studio (NASA SVS), “Animations of the August 12, 2026, Total Solar Eclipse – Following the shadow”, visualization by Ernie Wright (USRA), produced by Joy Ng (eMITS). NASA SVS – Eclipse 2026

From the Arctic to the Iberian Peninsula: the solar eclipse is sweeping across large parts of Europe

The path of totality will cross the Arctic Ocean, Greenland, Iceland, the Atlantic Ocean, and parts of Spain and Portugal on 12 August 2026. In large parts of Europe, the Sun will only be partially obscured by the Moon.

Solar eclipses have been predicted with precision since the Renaissance, such as by Edmond Halley, and Chinese historical records suggest that people in China were already engaged in the observation and possible prediction of solar eclipses some 4,000 years ago.

Thanks to highly precise observations and modelling of the Earth’s rotation and the Moon’s orbit, researchers can predict astronomical conditions such as the timing and path of a solar eclipse many years in advance, with an accuracy of less than one second and one kilometre. This makes it possible to calculate the onset, duration and degree of shading at the location of a specific solar power plant. By combining the Sun’s position with cloud cover and the characteristics of the plant, it is then possible to predict the plant’s power output during the solar eclipse.

Solar eclipses are a standard component of enercast’s power forecasts

enercast has been automatically accounting for solar eclipses in its solar power forecasts for many years. The effect is calculated individually for each location at 15-minute intervals within the enercast PFS, enercast PFA, enercast SEF and enercast YAS products. It is therefore incorporated into both current forecasts and backcasts.

Since 2026, several numerical weather prediction (NWP) models from the European Centre for Medium-Range Weather Forecasts (ECMWF) and the German Weather Service (DWD) have also taken the effects of solar eclipses into account. However, the data provided by these weather services represent the effects of a solar eclipse at a comparatively coarse temporal resolution, such as hourly intervals. enercast therefore applies specialized irradiation interpolation algorithms based on clear-sky models adapted to solar eclipses. This ensures that the attenuation of the PV generation is accurately reflected in the quarter-hourly solar power forecast, also when using these NWP models.

The forecast chart in the enercast portal shows how the bell-shaped curve typical of PV systems drops more sharply during the solar eclipse on the evening of 12 August 2026 than on other days. Depending on the location, the curve then either rises again shortly before sunset or gradually levels off.

Short totality and low evening sun limit the impact of the eclipse on PV generation

Even within the path of totality, the forecast curve does not necessarily drop sharply. For one thing, the fraction of the Sun covered by the Moon changes rapidly during the eclipse. At most locations, less than two hours elapse between the first contact of the Moon with the Sun’s disk and the end of the eclipse, with the event lasting only slightly longer in Iceland and Greenland. Even at the locations most affected, totality lasts for just over two minutes. As a result, the attenuation of the PV generation, averaged over each 15-minute interval, is never 100 per cent.

Another factor is that this year’s solar eclipse will take place in the evening – in Spain, for example, shortly before sunset. PV generation is already low at that time of day. Furthermore, cloud cover may make the additional reduction in solar power generation caused by the eclipse less noticeable.

Get to know more!

At enercast, we are constantly working to improve our forecasts of wind and solar power generation. If you would like to find out more about our latest product improvements and how you can benefit from them, please contact us.