The integration of hydrogen-based energy systems is crucial for decarbonizing stationary applications, where fuel cells can enhance grid flexibility and reduce emissions. However, fuel cell degradation affects efficiency, lifetime, and cost-effectiveness, influencing optimal system design. This thesis investigates the impact of degradation on the techno-economic feasibility of hydrogen energy systems by optimizing a multi-energy framework integrating photovoltaic panels, battery storage, and fuel cells. A MATLAB-based Mixed-Integer Linear Programming (MILP) model is developed to incorporate performance degradation into system sizing and operational strategies. Three degradation models are analyzed. The first, based on load spectrum analysis, highlights that start-stop cycles and high-power operation significantly reduce fuel cell lifetime, which is much lower than the expected 40,000 hours for stationary applications.