Energy communities are emerging as key enablers of the energy transition, facilitating greater electrification and providing essential flexibility services in urban energy systems. This study explores the economic performance of energy communities in Mediterranean cities, focusing on integrating solar generation with a battery energy storage system, electric vehicles, air-source heat pumps, and electric water heaters. Using a mathematical optimisation model applied to a case study in Catarroja, Spain, the research evaluates the techno-economic interactions of these technologies under different economic and regulatory conditions. The results highlight that combining solar generation with flexible technologies enhances economic viability. At the same time, the level of electrification plays a crucial role in determining the profitability of battery storage and photovoltaic systems. These findings underscore the importance of flexibility in designing and operating energy communities, offering valuable insights for policymakers and stakeholders aiming to optimise collective energy systems and support a sustainable transition.