Impacts of reflector positioning on horizontal bifacial photovoltaic module performance: an experimental case study

Abstract

Bifacial photovoltaic (bPV) technology, which converts solar irradiance from both the front and rear surfaces into electricity, represents a promising solution for enhancing solar energy conversion. While numerous studies have explored bPV performance under different environmental and geometric conditions, limited research has addressed the influence of horizontal reflector placement for horizontally mounted bPV modules, particularly under real-world conditions. This study fills that gap by experimentally evaluating the effect of five horizontal reflector configurations on the electrical performance of a bPV module. The experiments were carried out over three consecutive winter days on the rooftop of a university campus in Istanbul, Türkiye. Performance metrics included power yield and electrical efficiency, along with ambient temperature, relative humidity, wind speed, and module surface temperature. Results demonstrated that reflector positioning significantly influences performance, with reflector positions 2 and 3 consistently delivering the highest power output and efficiency. Average relative increases in power yield were 9.61 %, 13.88 %, 14.71 %, 9.54 %, and 5.43 % for positions 1 through 5, respectively. Corresponding average electrical efficiencies for positions 0 through 5 were 22.91 % (no reflector), 25.14 %, 26.08 %, 26.31 %, 25.12 %, and 24.18 %. These findings suggest that proper reflector placement enhances irradiance availability on the rear side of the module, particularly at low solar elevation angles, leading to notable improvements in performance. The study provides valuable experimental data under realistic conditions and contributes to the design optimization of bifacial PV systems, supporting the advancement of renewable energy technologies aligned with Sustainable Development Goals.