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When solar heating systems are worthwhile for industry

Fraunhofer ISE: Solar thermal energy pays off - process heat from solar energy can economically replace fossil systems

22.05.2025

Source: E & M powernews

A study by Fraunhofer ISE concludes that solar thermal energy can also be an economical solution for industrial heat supply in Germany.

Investing in solar thermal systems can be more economical than operating purely fossil-fired systems to generate process heat. This is the conclusion of a study published by the Fraunhofer Institute for Solar Energy Systems ISE. On behalf of the German Solar Industry Association (BSW-Solar), the scientists investigated the yields and economic efficiency of solar process heat compared to conventional industrial heat supply. The study "Solar process heat for German industry" is available online.

According to the results of the study, investments in solar thermal energy are more economical than fossil fuels in all scenarios examined if the solar share of heat generation is up to 50 percent. The payback periods for solar thermal systems are between three and eight years, depending on the scenario, location and temperature range - provided that an investment subsidy is claimed via the federal subsidy for energy and resource efficiency in the economy (EEW).

At the Würzburg site, for example, the investment in a 34 MW parabolic trough system with a 20 full-load hour storage system pays for itself in 5.5 years. At the same time, it would lead to cost savings of over 40 million euros over its lifetime (20 years). Discounted to today's value, this results in savings of around 25 million euros, whereby the investment of 12.6 million euros has already been taken into account.

The study is based on dynamic system simulations and considers various site-specific solar radiation values, collector technologies, temperature ranges and the integration of heat storage systems in over 6,000 simulated system configurations. In each case, real and forecast natural gas prices, CO2 taxes and existing funding instruments were taken into account.

The Fraunhofer study confirms "that an optimized system design and targeted support measures can significantly improve economic efficiency," said Carsten Körnig, Managing Director of BSW-Solar.

Author: Heidi Roider