Agrivoltaics for fir trees

Researchers from Germany's Fraunhofer Institute for Solar Energy Systems (Fraunhofer ISE) have installed a 135 kW grid-connected overhead solar PV plant designed to provide shading to two types of young fir trees.

At a height of 6 m, the shading effect of the agrivoltaic solution is similar to what fir trees grown in a southern German forest might experience, about 40% shading, according to the researchers.

The pilot is part of a land rehabilitation or renaturing initiative (Rekultivierung) initiative at a commercial quartz sand mine that belongs to German materials supplier Emil Steidle GmbH, which financed the project with additional support from the Ministry of Food, Rural Affairs, and Consumer Affairs of the Baden-Württemberg state.

“It is grid connected with 100% self-consumption during the week, and fed into the grid on weekends when the mine does not operate,” Fraunhofer ISE researcher, Oliver Hörnle, told pv magazine.

The installation has a steel and aluminum mounting system with a screw-style foundation and is meant to be removable and reusable. It is equipped with IBC MonoSol 405 modules from Germany’s IBC Solar.

Disassembly will take place after six to ten years, which is when the trees should reach the height of the racking. “It can be constructed and deconstructed without interfering with the surrounding area, such as harvesting lanes common in commercial forests,” said Hörnle noting that the timeframe is a range due to the novelty of the application.

In the meantime, the growth, height progress, and water requirements of the PV-shaded trees will be observed and compared with an adjacent unshaded reference plot in a study conducted by the Forest Research Institute Baden-Württemberg (FVA).

The hope is that the fir tree project will draw awareness to the potential for agrivoltaics in forestry. It is one of at least ten projects underway in southwest Germany as part of an agrivoltaic research initiative known as Modellregion Agri-Photovoltaik für Baden-Württemberg.