Image: Next2Sun GmbH

Vertical solar systems reduce need for gas imports and electricity storage

Leipzig researchers show in new study: Vertical solar plants on agricultural land offer enormous potential for energy transition

Solar energy is not subject to supply bottlenecks, is cheap and CO₂-neutral. In order to achieve maximum energy yield, solar plants are usually installed facing south with an angle of inclination of 20 to 35 degrees. This generates a lot of electricity primarily in summer and at midday. In the future, renewable energies are to completely replace fossil fuels – a major challenge. If solar modules continue to be installed primarily in a southern orientation in the future, additional electricity storage systems will be needed to compensate for fluctuations depending on the day and season. In a new study published in the specialist journal “Smart Energy”, a Leipzig research team shows that it would make sense in the future to install bifacial solar modules vertically as a matter of priority and to use agricultural land for this purpose, for example.

“Bifacial solar modules can use solar energy from both sides. Installed in an east-west orientation, most electricity is generated in the morning and evening. This would reduce the need for electricity storage while at the same time keeping the amount of land required for electricity generation low,” says Sophia Reker from the Leipzig University of Applied Sciences (HTWK Leipzig) and lead author of the study “Integration of vertical solar power plants into a future German energy system”. The researchers base their argument on a simulation of the German energy system using the Energyplan software.

New legislative package to accelerate expansion of renewable energies

In order to become independent of energy imports and reduce CO₂ emissions, the Bundestag passed a comprehensive package of legislation at the beginning of July to expand renewable energies in Germany. According to this, the share of renewable energies in total electricity consumption is to be increased from just under 50 percent at present to at least 80 percent by 2030. To achieve the goal, the framework conditions for new solar plants are to be improved, among other things.

“Bifacial solar modules are somewhat more expensive than conventional solar systems. But because they increase the number of hours of available solar energy, other electricity needs, such as at gas-fired power plants, are reduced. Installed vertically, solar arrays can be well sited on agricultural land. This creates additional income opportunities for farmers and increases the land potential for renewable energy in Germany to such an extent that we would only need to import a small amount of additional energy,” says Jens Schneider, Professor of Networked Energy Systems at HTWK Leipzig and co-author of the study. Solar panels installed on agricultural land can support the growth of certain crops by protecting the plants from wind and heat. Flowering strips for more biodiversity are possible directly under the modules. The German government’s new legislative package is intended to provide special support for so-called agri-photovoltaics in the future.

Modeling of the energy system in 2030 as a basis

For their study, Sophia Reker, Jens Schneider and Christoph Gerhards used Energyplan software to model an energy system for Germany that, in line with Germany’s climate protection targets, would produce a total of 80 percent fewer CO₂ emissions in 2030 compared to 1990. For this, the researchers assume an increase from currently 64 to 195 gigawatts of wind energy capacity and from currently 58 to 400 gigawatts of solar energy capacity. In order to actually use this installed power, electricity storage is needed. In their study, the researchers show that the need for electricity storage decreases when most of the added solar capacity is installed vertically in an east-west orientation. For example, in a scenario without additional electricity storage, more than 10 megatons of CO₂ per year can be saved simply by installing 70 to 90 percent of the added solar modules vertically in an east-west orientation rather than tilted to the south.

Sophia Reker studied energy, building and environmental technology in her master’s degree at the HTWK Leipzig. The paper is based on her 2021 master’s thesis. Reker works as a research associate in the research group of Prof. Jens Schneider. Sustainability and climate neutrality are a cross-cutting issue in research and teaching at HTWK Leipzig.