Electrical grids are undergoing a transformation driven by the increasing integration of renewable energy sources on the consumer side. This shift, alongside the electrification of consumption—particularly in areas such as electric mobility—has the potential to significantly reduce CO₂ emissions. However, it is also contributing to a rise in electricity prices due to growing demand and infrastructure costs. Paradoxically, these higher prices serve as a catalyst for further investment in renewable energy technologies by reducing the payback periods of such systems. Recent European legislation has accelerated this transformation by mandating the liberalization of energy markets. This regulatory shift enables the emergence of prosumers—consumers who are also producers of energy—by granting them the right to generate, store, and trade electricity using the existing distribution grid. In this new landscape, photovoltaic systems represent a viable and increasingly attractive investment option for both households and businesses. This study presents an economic evaluation of photovoltaic system investments across different European countries, focusing on key indicators such as payback periods and the impact of local solar irradiation on the resulting electricity price. The analysis provides insight into the varying economic feasibility of distributed solar energy deployment, offering a comparative perspective that supports both policymakers and potential investors in making informed decisions about renewable energy adoption.

Digital Twin (DT) technologies are increasingly central to the decarbonisation of energy systems, enabling close coupling between physical infrastructures and continuously updated virtual models. Through real-time data exchange, simulation, and predictive analytics, DTs support advanced monitoring, optimisation, and control of distributed renewable resources. This paper reviews the evolution of DT applications in the energy domain, tracing their development from asset-level simulations and supervisory control systems to hybrid, community-scale architectures that integrate multiple energy vectors, stakeholders, and governance layers. Drawing on recent literature published between 2022 and 2025, the review identifies key conceptual, computational, and institutional shifts underpinning this transition, including hybrid physics–data modelling, edge–cloud orchestration, co-simulation, and artificial-intelligence-assisted forecasting, alongside growing attention to interoperability, privacy, and social legitimacy. The analysis is anchored in the SMART (SMart transition to renewAble eneRgy communiTies) project, implemented within the Culatra2030 Sustainable Energy Community in southern Portugal. SMART is presented as an application-oriented DT framework that addresses persistent gaps in the literature, notably the limited long-term validation of DTs, the weak integration of participatory governance, and the misalignment between technical optimisation and community values. The proposed architecture conceptually couples distributed photovoltaics, energy storage, and electrified mobility with cooperative governance mechanisms. It integrates interoperable individual energy management systems, a central smart monitoring and control platform, and a web-based user interface that enables both operational coordination and citizen engagement. The paper argues that DTs are evolving into socio-technical infrastructures mediating technical performance, institutional design, and human behaviour, positioning renewable energy communities as living laboratories for energy transitions.