Aerosols affect solar power yield in Europe

Research project by KIT, the German Weather Service and meteocontrol is investigating how tiny suspended particles in the air change the weather and the sun's radiation

The satellite image from October 17, 2017 shows an aerosol cloud over Germany, which originates from forest fires in Spain and Portugal. (Source:

The satellite image from October 17, 2017 shows an aerosol cloud over Germany, which originates from forest fires in Spain and Portugal. (Source:

Smallest particles lead to the formation of clouds high up in the atmosphere. If air currents carry Sahara sand to Europe, this also affects our weather. In the PermaStrom research project, a team of researchers from the Karlsruhe Institute of Technology (KIT), together with the German Weather Service (DWD) and the solar energy service provider meteocontrol, are investigating how such events can be better taken into account in weather forecasts. The findings should help to create more precise yield forecasts for photovoltaic systems. The Federal Ministry for Economic Affairs and Energy is funding the project with 2.5 million euros.

A weather forecast that is as accurate as possible not only helps plan the weekend trip, it is also crucial for the management of the power grids. Because the forecast of solar radiation is based on earnings forecasts for photovoltaic systems. Large-scale forest fires or the episodic transport of Saharan dust to Europe can, however, lead to clear false predictions of solar radiation on individual days. Ashes, dust and grains of sand release tiny particles into the atmosphere that contribute to cloud formation. If the photovoltaic yield forecasts are wrong, the missing energy must be made available elsewhere in the short term.

Scientists at KIT and DWD are working with solar energy service provider meteocontrol GmbH to investigate how atmospheric aerosol particles affect clouds and solar radiation in the project "Photovoltaic Yield Forecast for Better Management of the Influence of Atmospheric Aerosol on Power Grids in Germany and Europe "(PermaStrom). The main aim of the project is to better take these effects into account in the weather forecast and the photovoltaic yield forecast based on it. So far, this has not been the case at all or has been insufficient.

"For the investigations, we use both measurement data from weather stations and satellite data," says Bernhard Vogel, head of the "Trace substance modeling and climate processes" group at the Institute for Meteorology and Climate Research - Tropospheric Research at KIT. This data is processed in an extended numerical weather forecast system, which is operated by the DWD especially for this application.

In the previous PerduS project, the transport of Sahara dust to Germany was already examined and the predictions improved in this regard. According to the experts, however, that is not enough. It was both necessary to consider other types of aerosols, such as soot and dust caused by forest fires, and to model and predict the effect of these aerosol particles on cloud formation. "The latter, in particular, is still a challenge because the processes in clouds and their interaction with aerosol particles are not yet fully understood," says Axel Seifert from the DWD.

By combining observation data and an improved, physically-based modeling with the ICON-ART model system, the scientists hope to make progress in understanding these relationships and in concrete improvements in daily weather forecasts. This could also clarify whether clouds are actually different during a Sahara dust event and, if so, whether this difference can be attributed to the aerosol particles themselves.

Bridge between research and application in the power grid

As part of PermaStrom, meteocontrol GmbH is further developing the forecasting system, taking network operator requirements into account. "This means that the electricity network operators will be able to use the research results in the form of new forecast models in the future," says meteocontrol GmbH. The solar energy service provider is a developer and provider of professional monitoring and control systems for PV systems and portfolios. The company also creates solar power forecasts and energy and weather data analyzes.

In order to ensure that the users of the new predictions, which are specially optimized for energy meteorology, are involved in the development at an early stage, the project is accompanied and supported by the associated partners Amprion, 50Hertz and EnBW.


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