Tilt angle optimization for bifacial PV module: Balancing direct and reflected irradiance on white painted ground surfaces

This study investigates the performance of a 440 W bifacial solar photovoltaic (PV) module installed on the rooftop of the Technology Tower (TT) building at Vellore Institute of Technology (VIT), Vellore. The influence of tilt angle on energy generation was examined by systematically adjusting the module from 0° to 90° during sunny days in February 2024. Measurements were collected at one-hour intervals between 9:00 AM and 5:00 PM. To enhance rear irradiation, the ground beneath the module was painted with white reflective material. Key performance parameters were recorded, and irradiation ratios were calculated for each tilt angle. Results showed a maximum daily average power generation of 316.85 W at a tilt angle of 30°. The corresponding bifacial irradiation ratio ranged from 0.20 to 0.40. Daily average power exhibited a progressive increase from 0° to 30° tilt, followed by a decline to a minimum of 148.51 W at 90°. Interestingly, the irradiation ratio displayed the opposite trend, increasing from 0.32 to 0.96 at 90°. These observations suggest that while overall irradiation reaching the module increases with tilt angle, optimal power generation is achieved at a 30° tilt due to a balance between front and rear irradiance. This study highlights the critical role of tilt angle and ground reflectance when using white paint in maximizing energy output from bifacial PV modules. Within the experimental setup, the PV module's power output remained relatively stable for tilt angles between 13° and 45°, even when considering a 5 % measurement uncertainty. Further investigations are affirmed to explore the impact of seasonal variations and weather conditions on the performance of bifacial modules in this specific geographical location.