The installation of photovoltaic systems, converting solar energy into electricity, has grown dramatically. However, the intermittent nature of the electricity produced from these systems, due to their dependence on weather conditions, is putting a growing strain on the electricity grids, which can lead to outages. BERLIN Project, focusing on the reduction of energy consumption and CO₂ emissions in public buildings, addressed this issue whilst still making the most of our region’s solar energy potential. The project pilots implemented in four different Mediterranean regions (namely Italy, Greece, Israel, and Cyprus) using different technologies enhanced both the interest and capacity of public authorities in building energy retrofit.