The European Green Deal, with the aim of climate neutrality in the energy- and entire economic system by 2050, is intended to be achieved through efficiency enhancement measures of existing technologies and the deployment of new technologies to decouple the economy from greenhouse gas-intensive activities. In order to develop an energy system with an extensive amount of CO2-free electricity, studies indicate that this can be achieved through renewable energy, electrification, energy efficiency, flexibility in both production and demand, hydrogen economy, carbon capture and utilisation (CCU), and circular economy.

Consequently, one of the key challenges in current technology development is obtaining higher technological readiness levels beyond the "Proof of Concept" stage and operating in real-world environments. To ensure an optimal integration of technologies into existing energy systems, comprehensive validation and demonstration strategies are required in actual operational settings.

A promising methodology to accelerate the implementation phase of developed prototypes is the "Power System Hardware in the Loop (PSHIL)" approach. PSHIL tests combine the benefits of numerical simulations and hardware testing by utilizing actual physical energy exchange between real components, allowing for improved testing and validation under realistic and extreme operating conditions.

In this context, we have established a PSHIL laboratory to conduct extensive testing and validation of multi energy systems, including PV inverters, energy storage systems such as a flywheel energy storage, electric vehicle charging infrastructure, energy management systems, and power-to-heat systems.

In this study, we provide an innovative approach for conducting timely resolved multi energy system tests with physical interconnections to the aforementioned technologies in order to investigate feedback effects on the energy system and its components. This bidirectional interaction between energy system models and physical system components opens up a new field of research for flexible energy supply systems, which is normally investigated through extensive laboratory and field tests. Accordingly, the results of the system tests include a significant step forward in understanding the complex interactions between various components of an energy system, recommendations for grid-compliant operating behaviour as well as optimisation approaches for the grid's interaction with key technologies.