The THERESA test facility is used to investigate and validate scientific issues relating to the flexibilization of thermal energy plants through the use of energy storage systems. For this purpose, the THERESA test facility has an electrically heated steam generator and steam storage (power to heat) as well as a thermal battery developed in-house. Furthermore, it is possible to test components at the experimental plant in order to answer questions regarding function, efficiency and durability (pressure and temperature load), for example. Therefore, the steam generator is designed for a very wide control range and can be operated very variably. In addition, the plant has a downstream controllable electric superheater and a controllable saturated water injection system. This makes it possible to precisely adjust the process parameters pressure, temperature and steam content to reproduce water-steam processes under defined conditions. The THERESA experimental plant is also used in teaching at the Zittau/Görlitz University of Applied Sciences and offers practical application areas for engineering students.