Study reveals rear-side performance losses in bifacial trackers

With the growing adoption of bifacial solar panels, researchers at Universidad Politécnica de Madrid have developed an experimental method to calculate structure shading factor (SSF) and mismatch losses (MML) on the rear side of modules mounted on single-axis trackers. The study found that rear irradiance is more spatially uneven than front-side exposure, making SSF and MML critical for performance evaluation. SSF was 10.0% for one-in-portrait (1P) trackers and 2.7% for two-in-portrait (2P). MML ranged from 0.21% to 0.46%, depending on module layout and cell type. Tracker geometry, such as torque tube spacing and panel gaps, was shown to affect both metrics. Although SSF and MML uncertainties increase in annual models, the impact on total energy yield uncertainty remained below 1%, supporting reliable integration into performance predictions.