Unlocking the potential of unregulated rooftops for solar PV on residential buildings: Identifying and addressing key challenges

Buildings represent one of the largest energy-consuming sectors globally, accounting for over one-third of final energy use and carbon emissions, underlining the urgent need to transition this sector towards sustainability. Integrating solar PV onto building rooftops offers immense potential to meet onsite electricity needs from clean, renewable sources while alleviating grid dependence. However, the availability of rooftops for PV panel installation varies significantly, with architectural, structural, and service-related features posing significant barriers to widespread PV adoption, especially in the Middle East. This study examines the restrictive impact of these obstacles and explores potential solutions to optimize rooftop utilization for PV deployment. Comprehensive audits of 30 residential buildings first identified prevalent obstructive features on rooftops, including parapet walls, stairwells, water tanks, AC units, and service equipment. Detailed 3D modeling of a representative apartment block with similar hurdles revealed an extremely low roof utilization factor of just 28 % available for PV installation in the base case. To address this underutilization, the study examines three distinct rooftop optimization scenarios: rearranging movable obstructions (Case B); lowering parapet wall height (Case C); and constructing an elevated PV canopy or “fly-roof” over existing obstructions (Case D). Advanced building-integrated PV simulations demonstrate progressively higher energy yields from the rooftop interventions, with the fly-roof maximizing utilization and annual generation. However, a multi-criteria assessment incorporating technical, economic, regulatory and social perspectives revealed that pragmatically rearranging rooftop obstructions (Case B) was the most preferred solution with a score of 0.311, followed by Case C (0.262) and Case D (0.190). These findings provide valuable insights for optimizing rooftop PV applications in regions facing similar challenges. The study contributes to advancing scientific understanding of rooftop PV optimization strategies and offers actionable recommendations for policymakers, building designers, and PV professionals to accelerate the deployment of distributed solar energy systems.