Scientists have enhanced the efficiency of photoelectrochemical (PEC) cells for green hydrogen production by conducting research on the impact of operating pressure on water splitting. The team at HZB discovered that increasing the operating pressure to 8 bar can halve total energy loss, leading to a potential 5-10% increase in overall efficiency. By evaluating the benefits and drawbacks of elevated pressure operation, the study highlighted the importance of bubble characteristics, gas crossover, and optical losses in achieving optimal device performance. Published in Nature Communications, the findings suggest an optimum pressure range of 6–8 bar for minimizing losses during PEC water splitting. Using a multiphysics model, the researchers were able to assess how pressure affects gas bubble size and behavior at electrodes. The study's results not only contribute to improving green hydrogen generation but also have implications for enhancing the efficiencies of other electrochemical systems. This research signifies a step forward in the development of sustainable energy technologies and emphasizes the role of elevated pressure in optimizing the production of green hydrogen.