Experimental analysis of vertical bifacial photovoltaics with flat and curved reflectors under tropical climatic conditions

The 21st century is increasingly defined by climate risks, and the global energy transition depends heavily on solar photovoltaics because of their scalability and declining costs. Within advanced photovoltaic designs, bifacial modules are attractive as they capture both direct and reflected irradiance, with reported gains of 10%–50% when optimized through tilt, elevation, or reflector use. Vertical bifacial photovoltaic systems provide added advantages such as reduced soiling, tolerance to partial shading, and alignment with grid demand peaks, making them well suited to diffuse-rich tropical regions. Despite extensive modeling and pilot studies, experimental comparisons of reflector geometries in such systems remain limited. This study addresses that gap through a controlled analysis of vertical bifacial modules integrated with flat and curved reflectors at tilt angles from 0° to 40° under tropical conditions. Results show that flat reflectors tilted between 20° and 30° deliver the most consistent improvements. F20 achieved up to 51% gain at noon, while F30 provided 15%–20% higher daily mean output and reduced the duck curve depth from 0.77 to 0.51. Curved reflectors reduced variability by about 18% and offered localized benefits such as 39% gain at 15:30 for C20, but suffered from non-uniform irradiance, hotspot formation, and fill factor collapse to 0.30 at 65 °C. Overall, flat reflector-assisted systems achieved superior peak power gain ratios of 1.2 in the morning, 1.27 at noon, and 1.75 in the evening, confirming their practicality for scalable and climate-resilient deployment.