Solar Energy to Replace Fossil Fuel-Based Heating at Mahle Plant

November 2, 2026

Source: E & M powernews

Automotive supplier Mahle has commissioned a PVT system with over 1,000 modules in Vaihingen an der Enz. It is expected to cover nearly all of the plant’s heating needs with solar energy.

Automotive supplier Mahle has fully commissioned what is currently Germany’s largest photovoltaic-thermal (PVT) system. The system combines the generation of solar electricity and solar heat within the modules. With this project in Vaihingen an der Enz, the company aims to replace the site’s heating needs—which have been met primarily by fossil fuels to date—almost entirely with renewable energy.

The system covers an area of 2,000 square meters and includes more than 1,000 hybrid modules from the Dresden-based startup Sunmaxx, a geothermal probe field, and a heat pump. The electrical output is more than 430 kW. The projected annual thermal energy production is 1,086 MWh. This is expected to cover nearly the plant’s entire heating demand.

The geothermal probe field plays a central role as a seasonal heat storage system. In the summer, excess heat from the PVT modules is stored in the geothermal probes. In the winter, it serves as a heat source for the heat pump. In this way, the solar-generated heat can be used at a later time.

Automotive Technology for Energy Generation

In this project, Mahle is applying its thermal management expertise from the automotive sector to energy technology for the first time. The company developed special cooling plates for the rear side of the PVT modules. These absorb the heat generated by the solar cells during electricity production and transfer it to a heat transfer fluid. At the same time, they limit temperature-related power losses in the solar cells.

The cooling plates are thermally connected to the photovoltaic modules across their entire surface. According to Mahle, this improves heat transfer compared to conventional PVT modules, in which the rear finned heat exchangers are connected to the PV module only at specific points. The significantly improved heat transfer enables more efficient utilization of the heat generated in the solar cells.

The technology is based on components that Mahle already uses in series production for electric vehicles. In Vaihingen, it is being used for the first time to regulate the temperature of PVT modules.

“With our PVT plant in Vaihingen, we are building a unique bridge between mature automotive technology and pioneering energy technology, thereby underscoring the consistent implementation of our sustainability strategy,” explained Martin Wellhöffer, a member of Mahle’s Group Executive Board and head of the Thermal and Fluid Systems business unit.

The company also views the implementation at this site as an example of the industrial integration of renewable energy. “We are particularly proud to have installed this forward-looking technology here at the site—and to have done so using existing infrastructure without interrupting ongoing operations,” said Plant Manager Joachim Wulff.

Interest from the Regional Business Community

The facility is intended to serve as a reference project for the industrial supply of solar power and solar heat. According to Mahle, companies from the region have already expressed interest in the technology.

The plant in Vaihingen an der Enz was founded in 1979 and employs approximately 200 people. It is Mahle’s only European site for Visco products such as fans and pumps. These components regulate engine cooling based on actual cooling demand.

Author: Susanne Harmsen