The development of renewable energy sources is putting more strain on electricity systems. Effective energy management requires precise projections of the amount of solar power that will be sent into the grid.
Aerosol particles, in addition to clouds, have a significant impact on the amount of electricity generated by photovoltaic systems. Current air quality models are a useful starting point for predicting solar energy production.
They should, however, be improved further. Researchers from Bonn-Rhein-Sieg University of Applied Sciences’ Leibniz Institute for Tropospheric Research (TROPOS), the German Weather Service (DWD), and the International Centre for Sustainable Development (IZNE) came to this conclusion.
They contrasted the Copernicus Atmosphere Monitoring Service (CAMS) reanalysis with real solar radiation measurement data from 25 DWD sites in Germany for a year as part of the collaborative project “MetPVNet.”
The research was just published in Atmospheric Chemistry and Physics (ACP). Clouds and greenhouse gases are not the only factors that influence the temperature of the atmosphere.
The Future of Solar Energy looks at only two well recognized technologies for turning solar energy into electricity: photovoltaics (PV) and concentrated solar power (CSP, often known as solar thermal) in their current and possible future forms.
Aerosol particles play a significant influence as well. The microscopic particles (also known as particulate matter) float in the air, reflecting and absorbing some of the sun’s energy despite their small size. The extent to which this factor influences the amount of electricity generated by photovoltaic (PV) systems is currently unknown.
In our study, we were only able to study one year. However, solar radiation and air quality sometimes fluctuate significantly between years. Therefore, in the next step, we want to consider a longer time period, from 2003 to 2021, and we are curious to see whether our findings from 2015 are also applicable to other years.
Jonas Witthuhn
Experts from atmospheric research and the field of renewable energies collaborated in the interdisciplinary research project “MetPVNet” to (further) develop innovative energy meteorological methods for predicting irradiation and PV output at the plant level, and to test them with real-world partners.
The expense of small-scale PV generating is often overcome by the very high value of access to power for lighting and charging mobile phone and radio batteries for the more than one billion people in the developing countries who lack access to a stable electric grid.
Furthermore, in some poor countries, solar generating may be cost-effective in reducing reliance on imported oil, particularly if that oil must be transported by truck to remote generator sites. Both of these important functions for solar energy in the developing world are discussed in a companion working paper.
A study was done as part of the joint project, which spanned from 2017 to 2021, and it has now been published. Using two alternative modeling methodologies, this study investigated the radiative influence of aerosol on the ground and within the atmosphere in Germany during 2015. To begin, data on solar radiation in cloud-free conditions were analyzed at 25 stations across Germany from the German Weather Service’s (DWD) observation network and the global AERONET network.
The radiative effect, on the other hand, was calculated using explicit radiative transfer models based on the Copernicus Atmosphere Monitoring Service (CAMS) of the European Union (ESA) reanalysis of atmospheric composition.
The evaluation, which has now been published, showed that there is a clear solar energy gradient in Germany: due to the sun’s higher position, it shines more intensely in the south of the Federal Republic on an annual average of up to 0.5 megawatt hours per square metre than in the north on an annual average of up to 0.5 megawatt hours per square metre.
Solar energy is diminished in the east of Germany compared to the west due of aerosol from continental sources. Both influences combine to ensure that yearly average photovoltaic system yields on the Neisse River in eastern Germany are up to 0.05 megawatts per square metre lower than in the Alps in southern Germany. Other contributing elements, like as cloud cover and the height of the solar installation, play a role in practice.
“The radiative effect of aerosol should definitely be taken into account in daily solar power forecasts. The CAMS model of the European climate observation programme Copernicus is a good basis, but it should also be further improved so that grid operators can better control the increasing share of electricity from photovoltaic systems in their power grids. Our basic research thus provides an important building block for the energy transition and emphasises the social relevance of aerosol research beyond air quality,” emphasises Dr. Hartwig Deneke, head of the Satellite Remote Sensing working group at TROPOS.
His research group primarily employs satellite data to look into the features of clouds and aerosols, as well as their impact on solar and terrestrial radiation.
The study also emphasizes the importance of ground measurements of solar radiation as a reference, because actual solar energy on solar arrays varies widely and can only be predicted in part by air quality models thus far. The published analysis is a significant step toward a reliable solar weather forecast, but there is still a long way to go.
“In our study, we were only able to study one year. However, solar radiation and air quality sometimes fluctuate significantly between years. Therefore, in the next step, we want to consider a longer time period, from 2003 to 2021, and we are curious to see whether our findings from 2015 are also applicable to other years,” explains Jonas Witthuhn from TROPOS.
An enhanced estimate of photovoltaic output will assist not just electrical grid operators in Germany, but also the rest of the world. Tilo Arnhold
