This report (in Portuguese) is the third and final study in the trilogy developed for the Telheiras/Lumiar Renewable Energy Community (CERT/L) within the European Energy Communities Facility. Building on the analysis of real operational performance and the assessment of photovoltaic potential in public buildings, it integrates technical, economic and financial modelling to support the CERT/L Business Plan for 2026–2030. The analysis represents the phased development of new photovoltaic systems, growth in community membership, renewable generation and energy sharing, while distinguishing the perspectives of the community operator, public producers, regular consumers, social/vulnerable members and additional local renewable-energy producers. The report assesses both a core scenario based on community-financed photovoltaic installations and a broader scenario incorporating additional producers and complementary liquidity financing. Key dimensions include capital and operating expenditure, recurring revenues, electricity-bill savings, the solidarity mechanism for vulnerable households, financing requirements and operational cost coverage. The modelling shows that the core community model can cover its recurring operating costs at scale, while most of the economic value generated is intentionally distributed to participating households and public producers through electricity-bill savings rather than retained as organisational profit. By 2030, the complete model considered in the study reaches approximately 1.06 MWp of participating photovoltaic capacity, annual renewable generation of around 1.53 GWh and approximately 1,345 members, while maintaining a high utilisation of electricity available for community sharing. The analysis therefore provides an integrated evidence base for strategic planning, financing and decision-making, while demonstrating how the economic performance of a citizen-led energy community must be evaluated across multiple actors and benefit streams.