Analysis, evaluation and development of sustainable system concepts for solar district heating systems with seasonal thermal energy storage

Brief description

In the futureSuN project, existing solar district heating systems in Germany are analyzed, evaluated and, based on that, sustainable solar district heating concepts with seasonal thermal energy storage are developed. The overall project includes several subprojects by several project partners:

  • Subproject “Transformation of solar district heating systems in the context of the Energy Transition 2050”, managed by SIZ energie+
  • Subproject “Evaluation of existing and sustainable system concepts for solar district heating systems with seasonal thermal energy storage”, managed by IGTE, University of Stuttgart
  • Subproject “Cross-evaluation of seasonal solar long-term energy storages in district heating systems”, managed by ZAE
  • Subproject “Evaluation of the solar district heating systems with seasonal thermal energy storages from the research concepts Solarthermie2000 and Solarthermie2000plus”, managed by SIZ-EGS

The basis and starting position for futureSuN are the pilot systems and storages realized from 1993 to approx. 2010 in the funded projects “Solarthermie2000” and “Solarthermie2000plus”.

In the project, the respective current expansion and operating status are identified. The system is evaluated as comprehensively as possible. Based on this evaluation, measures for an increase in efficiency and for the optimization for the existing systems are identified and presented to the operators; future innovative system concepts for solar district heat supply are developed, in combination with seasonal thermal energy storage. Especially for the newly developed system concepts, the interaction between thermal energy and electricity (sector coupling) is considered in its entirety.

The futureSuN project contributes to the expansion of Germany’s technology leadership in the field of solar district heating and seasonal thermal energy storage and, as a result, contributes to the increase in the international competitiveness of German companies and research institutions as well as to the creation of future sustainable, high-quality jobs.


Project duration

04/2017 - 09/2019


Project partners

Joint research project coordinator:

  • Steinbeis Innovationszentrum (SIZ) energie+, Germany

Joint research project partners:

  • Bayerisches Zentrum für Angewandte Energieforschung (ZAE), Garching, Germany
  • SIZ-EGS Steinbeis Innovationszentrum für Energie-, Gebäude und Solartechnik, Stuttgart, Germany



The futureSuN project is funded by the Federal Ministry for Economic Affairs and Energy (BMWi), based on a decision of the German Bundestag, via Project Management Jülich (PtJ) under grant number 0325897A-C. The authors would like to sincerely thank for their support and take responsibility for this publication.


Dr.-Ing. Harald Drück

Dr.-Ing. Harald Drück

Research Coordinator and Team Lead

To the top of the page