Tübingen commissions large solar thermal park Au and large heat storage facility

25.11.2025

Source: Stadtwerke Tübingen GmbH and Alois Müller GmbH

With the new Au solar thermal park and the associated large heat storage facility, Tübingen has taken an important step on the path to climate-neutral heat supply.

The plant is one of the largest solar thermal parks in southern Germany and by far the largest solar thermal generation plant in Tübingen and the region to date. As the first renewable heat source in the planned heat transformation of Stadtwerke Tübingen (swt), it plays a key role in the university city's goal of becoming climate-neutral by 2030.

Strong contribution to the heat transition

With an installed heat output of 7 MW and an expected annual heat generation of around 6,000 MWh, the solar thermal park will cover an important part of the growing district heating demand in future. In total, around 880 tons of CO₂ can be saved per year.

In order to fully exploit the potential of the plant, swt is also building a 1,250 m³ large heat storage tank. This will allow the solar thermal energy to be flexibly integrated into the municipal heating network and increase security of supply. The project is being supported with 5.6 million euros from the federal subsidy for efficient heating networks.

Technology at a glance

• Location: Tübingen, B27/B28 junction
• Collector area: 12,000 m²
• Heat generation: 6,000 MWh/year
• Heat storage tank: 1,250 m³
• CO₂ savings: 880 t/year

Building technology of the system:

• Flow 95/85 °C
• Return flow 50-65 °C
• Heat output up to 3.7 MW
• Water volume 105 t/h
• 210 m³ pressure equalization tank

Alois Müller GmbH played a central role in the implementation. It realized the heat extraction into the district heating network, the pressure maintenance as well as the complete heating, ventilation and sanitary technology of the company building.

A model for the region

With a total area of 23,000 m² and 12,000 m² of collector surface, the Au solar thermal park is one of the most important solar heating projects in Germany. The combination of renewable generation and large-volume storage is set to serve as a blueprint for other cities in the future.

Stadtwerke Tübingen speaks of a "real milestone". The plant shows how municipal heating networks can be decarbonized quickly and efficiently with the help of modern solar thermal energy.