To realise the installation targets of 10 GW electrolysis capacity in Germany and 40 GW in the EU until 2030, extensive standardisation and testing is required. The electrical characteristics of electrolysers need to be fully understood and mastered for a reliable operation within distribution grids and decoupled grids of systems to produce green hydrogen, e.g. off-shore. Using a modular test infrastructure and multi-functional test pads, electrolysers, but also fuel cells and CHP units, can be tested in emulated grid conditions. To emphasize the range of feasibility regarding testing, three different scenarios were developed, covering the challenges between single unit grid connection and offshore hydrogen production. The test results serve as input for standardisation committees to expand existing and develop new guidelines.