High-Reflectivity Ground Covers for Energy Yield Enhancement in Single-Axis Tracked Bifacial Photovoltaic Systems: Field Evidence from Brazil

Artificial high-reflectivity ground covers are a potential strategy to increase rear-side irradiance and energy yield in bifacial photovoltaic systems, especially in utility-scale plants with single-axis trackers. This paper reports field evidence from a pilot plant in southern Brazil (27.4°S, 48.4°W), where four reflective covers—a white film, a pearl-white film, a black-and-pearl film, and a white geomembrane—were evaluated against a gray gravel reference. The study combines albedo and spectral characterization, rear-to-front irradiation ratios, energy-yield comparisons, soiling assessment, thermal analysis, and operational observations. Broadband albedo increased from 25% for gray gravel to 53–58% for the reflective films and 72% for the geomembrane. Reflective films increased the rear-to-front irradiation ratio to around 20% and delivered energy gains close to 9%, while the geomembrane achieved the highest irradiance enhancement and gains exceeding 10%. Inverter current limitations led to clipping, indicating that measured gains may underestimate the full energy potential of the reflective covers. Estimated thermal losses were insignificant compared with measured gains, while soiling and fixation methods affected long-term feasibility. The results confirm the technical potential of reflective covers, while showing that utility-scale deployment must consider not only optical performance, but also optical stability, electrical limitations, cleaning and anchoring requirements, drainage adaptations, operation and maintenance practices, and cost constraints.