Optimizing tilt angles for solar energy harvesting on building façades: evidence from Babolsar, Iran

The production, conversion, and utilization of energy are central contributors to global environmental challenges. Among the various renewable energy solutions, solar energy has emerged as a promising and scalable option. The efficiency of photovoltaic (PV) systems, especially in building applications, is highly dependent on the configuration of the panels—particularly their tilt angle. This study investigates the optimal tilt angles for PV panels installed on the south-facing façades of buildings in Babolsar, Iran, with the goal of maximizing annual solar radiation reception and energy yield. Using the Liu and Jordan isotropic sky model, combined with meteorological data and custom MATLAB simulations, monthly, quarterly, and fixed-angle strategies were analyzed. A system capacity of 1.5 m² panel area was assumed, with annual energy output ranging from approximately 336 kWh/year for a flat (0°) installation to 377 kWh/year with monthly tilt adjustment. Economically, the quarterly strategy offered the highest return on investment (ROI), with an estimated payback time of 7.8 years and a levelized cost of electricity (LCOE) of approximately $0.083/kWh. Environmentally, the optimized system reduces CO₂ emissions by approximately 180 kg/year compared to conventional grid-based electricity. A fixed optimal tilt angle of 30° was also found to be a practical, low-maintenance alternative. These findings provide both technical and environmental insights for enhancing the efficiency and sustainability of solar energy systems in Babolsar and similar climates.