© BMWi/ Holger Vonderlind
And now to the dust forecast
Many of you will know all too well how dust likes to settle where you least want it. What applies to cars, for example, also holds good for solar installations all over the country.
Some of this dust has not been stirred up here but far away in the Sahara desert. Mineral particles from the desert accumulate in the air and may under certain atmospheric conditions arrive all the way here in Central Europe. That is rather a long way for a grain of sand: the distance from the south of Germany to the northern parts of the Sahara desert alone is around 4,000 kilometres.
PV capacity lowered by up to 20 per cent
Once it arrives in Germany, the desert dust starts to make itself known. For example, it is responsible for solar installations producing less energy. This is not only because it settles on PV systems and other installations, but also because the small particles cloud the atmosphere. Less solar radiation means less solar power.
Initial preliminary studies show that a high amount of dust in the air can lower PC capacity in Germany by 10 to 20 per cent merely due to the additional clouding of the atmosphere. This does not include the dust that accumulates on the PV modules in the following days. What is needed is a reliable dust forecast. This is exactly what scientists are working on in the PerduS project.
Dust forecasting thanks to PerduS
PerduS is short for “Photovoltaic Yield Reduction Caused by Saharan Dust” and aims to predict how the Saharan dust will affect the performance of photovoltaic installations. Performance prediction systems for photovoltaic installations already exist today. However, they cannot yet realistically predict the effects of Saharan dust. PerduS combines all of the components necessary for this task.
The German Meteorological Service (DWD) is working on the project in collaboration with the Karlsruher Institute for Technology (KIT) and company meteocontrol. Dr Bernhard Vogel, meteorologist at the KIT, explains: “During an outbreak of Saharan dust, atmospheric streams transport the dust whipped up by the Sahara over great distances and take it all the way to central Europe. In terms of a long-range average, we see this four days a month in Germany during spring and summer. In some years, this might even be up to nine days in a month.”
Weather forecasting system is being enhanced
The basis for PerduS is the weather forecasting model “ICON” developed by the DWD. Its functions are being expanded in cooperation with the KIT to include dispersion forecasts for desert dust. It can therefore simulate how the dust from the desert will likely disperse in Germany and also make predictions concerning how it will affect solar radiation. This will form the basis for the weather forecasting and monitoring company meteocontrol to predict the performance of photovoltaic installations. Everything is accounted for: for the prognosis, even subsequent rains which will wash off the settled Sahara dust are taken into consideration.
The Federal Ministry for Economic Affairs and Energy is funding PerduS for four years: from March 2016 until February 2020.