Optimization of Rooftop PV Layouts in Baghdad Using 3D Shading and PVsyst with Energy-Density Approach

Abstract

This work focuses on a common real rooftop PV challenge in Baghdad: roof space is limited and usually includes obstacles such as rooftop rooms, parapet walls, water tanks, and service structures. These objects create near-shading that can reduce annual energy yield and even change how PV design options rank against each other. Because of this, comparing alternatives using annual energy only can be misleading. A design may look “better” simply because it installs more capacity and occupies more roof area. To address this, several rooftop PV variants are evaluated using an integrated workflow that links detailed 3D modeling of the roof and obstacles with PV performance simulation. A near-shading scene is built in 3D and imported into PVsyst, so the annual results include shading impacts along with practical loss terms such as soiling, system unavailability, and aging. The tested variants represent common rooftop strategies, including fixed shading-aware layouts, seasonal adjustment, and tracking. The results show that the highest-energy option is not always the most feasible choice. The maximum annual production, 272,308 kWh/yr, is achieved by the tracking configuration (Variant 4: HJT_680_L_Tracking), while the highest performance ratio, 85.22%, is achieved by the seasonal-adjustment configuration (Variant 3: HJT_680_L_Seasonal). Considering practicality and economics, the fixed shading-aware design (Variant 5: HJT_680_P_Shading) is recommended as a balanced rooftop solution, producing 181,510 kWh/yr with LCOE = 0.0245 USD/kWh and a payback period of 2.8 years