ISES mourns the loss of Prof. Volker Wittwer

In Memory of Prof. Dr. Volker Wittwer
25 June 1944 – 1 October 2025

In October, the solar energy community learned of the passing of a dedicated researcher and long-time contributor to solar energy innovation – Prof. Dr. Volker Wittwer.

Prof. Dr. Wittwer was an active and treasured ISES member for many years. Here at the ISES Headquarters, the historic Villa Tannheim, Prof. Dr. Wittwer even applied his many years of expert solar knowledge when the Headquarters received a major energy-efficient renovation.   

With this text, we wish to express our deepest sympathies to his family, friends, and colleagues and to honor his lifetime dedication to solar energy research.

Prof. Dr. Volker Wittwer studied physics at the Technical University of Munich, completing his doctorate in solid-state physics in 1974. He began his Fraunhofer career immediately afterwards at the Fraunhofer Institute for Applied Solid State Physics (IAF) in Freiburg. In 1979, he took over the leadership of the “Fluorescence Collector” working group under Prof. Dr. Adolf Goetzberger, developing technologies for concentrating sunlight and later contributed to the founding of the Fraunhofer Institute for Solar Energy Systems (Fraunhofer ISE) in 1981.

As one of Fraunhofer ISE’s founding members, Prof. Dr. Wittwer led the Department for Thermal and Optical Systems for more than 24 years and served as Deputy Director of the Institute from 1997 to 2006. In 2007, he received an honorary professorship at the University of Freiburg and continued to teach and mentor students, supervising numerous diploma and doctoral theses. Even after his retirement in 2009, he remained closely connected to Fraunhofer ISE as a consultant.

He was recognized internationally for his expertise, serving for example on the editorial board of the ISES journal Solar Energy and in 2006 Prof. Dr.  Wittwer received the Solar Heating and Cooling Award by the International Energy Agency (IEA).

ISES mourns the loss of a remarkable scientist and highly esteemed colleague. Our heartfelt condolences go to his family and friends. Prof. Dr. Wittwer’s dedication and contributions to solar energy will be remembered and cherished.