Within the framework Solar Heating and Cooling Programme of the International Energy Agency Task 51 “Solar Energy in Urban Planning”, case studies from Norway, Sweden, and Denmark were collected and analyzed through a comparative approach. The cases were first classified based on their urban characterization (existing and new urban areas) and then compared within the same country or in a cross-country perspective according to three areas of interest (i.e., Scale and planning process, Legislation and planning process, Targets and goals). The comparisons follow a common template of five sections describing the role of the involved stakeholders and highlighting challenges, barriers, and opportunities for the deployment of active solar systems and passive solar strategies. Both technical and non-technical aspects are considered. Among the technical aspects, the focus is on the adoption of solar energy strategies (e.g., solar accessibility, daylighting), the estimation of solar potential and energy generation. Regarding the non-technical aspects, the focus is on identifying barriers and challenges for the adoption of solar systems in relation to national and local legislation. The findings show that municipalities can have a crucial role in facilitating the adoption of solar energy solutions in cities by embracing ambitious visions and storytelling, as well as being directly financially involved as owners or subsidizing bodies. The findings also demonstrate the value of the use of indicators to evaluate the performance of masterplans, the combination of analogue and digital tools in the design process, and the performance of solar simulations from early stages to foster awareness among the involved stakeholders. Despite these positives, the Scandinavian legislation on solar energy utilization in the urban context still displays fragilities, making the creation of guidelines a pressing need.

This paper presents the results of the analysis conducted on six case studies related to solar energy integration in urban and rural environments located on the Italian territory. The analysis has been carried out within the Subtask C—Case Studies and Action Research of the International Energy Agency Solar Heating and Cooling Program Task 51 “Solar Energy in Urban Planning”. Three different environments hosting active and passive solar energy systems (existing urban areas, new urban areas, and agricultural/rural areas) have been investigated to attain lessons learned and recommendations. Findings suggest that (a) it is important to consider solar energy from the early stages of the design process onwards to achieve satisfactory levels of integration; (b) a higher level of awareness regarding solar potential at the beginning of a project permits acting on its morphology, achieving the best solution in terms of active and passive solar gains; (c) when properly designed, photovoltaic systems can act as characterizing elements and as a distinctive architectural material that is able to valorize the aesthetic of the entire urban intervention; (d) further significant outcomes include the importance of supporting the decision strategies with quantitative and qualitative analyses, the institution of coordinating bodies to facilitate the discussion between stakeholders, and the need for deep renovation projects to fully impact existing buildings’ stock; (e) when large solar installations are planned at the ground level, a landscape design approach should be chosen, while the ecological impact should be reduced by carefully planning the adoption of alternative solutions (e.g., agrivoltaics) compatible with the existing land use.