Test of the inverter in the Multi-Megawatt-Lab of Fraunhofer ISE.
As the global energy transition accelerates, the shift from conventional rotating generators to inverter-based renewable energy sources—particularly solar—is transforming the structure and behavior of electricity grids. A groundbreaking German initiative, Project SUREVIVE, is addressing one of the most pressing challenges in this evolution: how to maintain voltage and frequency stability in a solar-powered future.
Led by Westnetz in collaboration with Fraunhofer Institute for Solar Energy Systems ISE, Schoenergie, and the University of Stuttgart, SUREVIVE is the first project in Germany to test grid-forming inverters and battery storage directly in the distribution grid under real-world conditions. Supported by Germany’s Federal Ministry for Economic Affairs and Energy (BMWK) under the OptiNetD funding call, the project is scheduled to run until June 2028.
Grid-forming inverters differ significantly from traditional inverters. While most solar inverters are grid-following—operating in sync with an existing grid frequency—grid-forming inverters can generate a stable frequency and voltage on their own, mimicking the behavior of conventional synchronous generators. This ability is crucial as conventional fossil-fuel plants are phased out.
In preparation for field deployment in Föhren (Rhineland-Palatinate) in October 2025, Fraunhofer ISE is conducting extensive pre-tests in its multi-megawatt laboratory in Freiburg. These include validating the grid-forming capabilities of a 20 MW / 55 MWh battery system, alongside a dedicated 5 MWh test system. The tests ensure the technology’s readiness for dynamic grid conditions and are paired with high-resolution simulations to assess system behavior under various grid scenarios.
“Our work at Fraunhofer ISE has focused for years on developing and refining grid-forming inverter technology. With this project, we are now bringing those innovations into real grid operation,” said Roland Singer, Group Manager for Converter-Based Grids at Fraunhofer ISE.
The results of the field tests will inform a best-practice guide for system manufacturers, project planners, and grid operators, paving the way for wide-scale adoption of grid-forming systems across Europe’s solar-rich networks. Additionally, the project aims to define generalized methods for grid stability assessments in inverter-based energy systems.
Project SUREVIVE represents a vital next step in future-proofing solar infrastructure, ensuring that the expanding role of photovoltaic systems in national grids is supported by robust, smart, and self-stabilizing inverter technologies.
