Study: Kassel funding for balcony power plants has an impact

The debate on the promotion of small solar power systems is in full swing at federal level. In Kassel, the number of so-called balcony power plants has recently risen sharply. One of the main reasons for this is a municipal subsidy for this type of solar power generation. This is shown in a thesis that has now been presented at the University of Kassel.

In 2025, the number of balcony power plants installed in Germany cracked the 1 million mark, and in Kassel alone there are already over 2,500. The small photovoltaic systems, also known as plug-in solar devices, mini solar systems or balcony PV systems, are inexpensive and do not need to be installed by a qualified electrician. They not only reduce your electricity bill, but also make your home more climate-friendly. Since October 2024, citizens of the city of Kassel in northern Hesse have been able to receive a subsidy for the purchase of a balcony power plant. It amounts to a lump sum of 150 euros per household.

Ronja Gehrke investigated the impact of the subsidy program on the city's installation figures for her master's thesis in the Sustainable Management degree programme at the University of Kassel. To do so, she analyzed data from the market master data register, in which all operators of a balcony power plant must register their system. "For the study period from October 2024 to June 2025, a significant increase in installation figures could be demonstrated. Using statistical methods, we can show that this effect is very likely due to the subsidy program," explains the Kassel student. Her supervisor Prof. Dr. Guido Bünstorf praised: "The work is of outstanding quality and convincingly demonstrates the effect of the subsidy."

To determine the effect, the development of installation figures in other major German cities that did not have comparable subsidies was used. As not all citizens registered their balcony power plants as required, the data in the market master data register is inaccurate and does not allow any precise statements to be made about the exact effect size. However, one effect in itself is undisputed: "With various assumptions, we can safely say that the subsidy program has increased the number of new balcony power plants installed by a factor of 1.5 to 3," Ronja Gehrke continues.

Contact:

Prof. Dr. Guido Bünstorf
Head of the Department of Economic Policy, Innovation and Entrepreneurship
Phone: +49 561 804-7403
Email: buenstorf[at]uni-kassel[dot]de

Ronja Gehrke
E-mail: ronja.gehrke[at]student.uni-kassel[dot]de
Further contact details on request

Press contact

Service für Presse und Medien (Press inquiries, requests and expert referrals)

Telephone: +49 561 804-1961
Email: presse[at]uni-kassel[dot]de

Website: Communications Office