Analyzing Rear-to-Front Irradiance Ratios in Bifacial HSAT Systems Across Varying Sky Conditions

This study investigates the rear-to-front irradiance ratio (RI/FI) in bifacial horizontal single-axis tracking (HSAT) systems under varying sky conditions. Data were collected from a solar farm in Delaware, featuring 4,464 bifacial modules having natural grass underneath and strategically positioned irradiance sensors. Days were classified into sunny, partially sunny, partially cloudy, and cloudy conditions using a daily Clear Sky Index (CSId). Preprocessed data revealed RI/FI dynamics influenced by tracking algorithms, seasonal variations, and weather patterns. Results show distinct RI/FI behaviors during Summer-Spring and Fall-Winter months, with rear irradiance contributing up to 20% during diffuse-light conditions. Heatmaps and daily profiles highlight key trends for optimizing bifacial HSAT designs. These findings enhance understanding of irradiance dynamics, guiding future improvements in bifacial PV system performance.