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September 10, 2025Open Access

Bifacial Solar Modules Under Real Operating Conditions: Insights into Rear Irradiance, Installation Type and Model Accuracy

Key Points

Bifacial photovoltaic modules showed a maximum energy output at a module tilt angle of 0°, indicating the optimal configuration for energy generation.
The study found a 32% variation in rear-side irradiance across the module, which affects overall energy performance and efficiency.
Using volcanic red stone as a reflective surface enhanced energy capture, demonstrating the importance of tailored installation settings for bifacial PV.
The thermal performance model predicted power outputs that exceeded measured values, highlighting the need for accurate modeling in bPV performance evaluation.

Abstract

Bifacial Photovoltaic (bPV) technology is rapidly becoming the standard in the solar photovoltaic (PV) industry due to its ability to capture reflected radiation and generate additional energy. This experimental study analyses the electrical performance of bPV modules under specific installation conditions, including varying heights, module tilt angles (MTA), and surface reflectivity. The methodology combines controlled indoor testing with outdoor experiments that replicate real-world operating environments. The outdoor test setup was carefully designed and included dual data acquisition systems: one with independent sensors and another with wireless telemetry for data transfer from the inverter. A thermal performance model was used to estimate energy output and was benchmarked against experimental measurements. All electrical parameters were obtained in accordance with international standards, including current-voltage characteristic (I–V curve) corrections, using calibrated instruments to monitor irradiance and temperature. Indoor measurements under Standard Test Conditions yielded at bifaciality coefficient φ=0.732, a rear bifacial power gain BiFi=0.285, and a relative bifacial gain BiFirel=9.4%. The outdoor configuration employed volcanic red stone (Tezontle) as a reflective surface, simulating a typical mid-latitude installation with modules mounted 1.5 m above ground, tilted from 0° to 90° regarding floor and oriented true south. The study was conducted at a site located at 18.8° N latitude during the early summer season. Results revealed significant non-uniformity in rear-side irradiance, with a 32% variation between the lower edge and the centre of the bPV module. The thermal model used to determine electrical performance provides power values higher than those measured in the time interval between 10 a.m. and 3 p.m. Maximum energy output was observed at a MTA of 0°, which closely aligns with the optimal summer tilt angle for the site’s latitude. Bifacial energy gain decreased as the MTA increased from 0° to 90°. These findings offer practical, data-driven insights for optimizing bPV installations, particularly in regions between 15° and 30° north latitude, and emphasize the importance of tailored surface designs to maximize performance.

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