Differential Analysis of the Angle of Incidence Response of Utility-Grade PV Modules

Anti-reflective coatings (ARCs) are commonly applied to commercial modules to reduce reflection losses and improve energy harvest. Relative performance at low incidence angle is often indistinguishable between different modules and it is only at high incidence angle that performance becomes differentiated. It is also precisely in this range that accurate measurements are the most difficult to obtain, complicating efforts to compare the benefits of different coatings. In this study, the performance of multiple commercial modules with different coatings were compared. A differential approach was employed, facilitating relative comparisons between test devices and a common reference. Using this method, performance differences at high incidence angles could be visualized and quantified. Differential analysis was extended to multiple system performance models in order to predict and quantify potential improvements in annual energy harvest. Improvements were observed upwards of 1% seasonally and 0.5% annually for the best performing coatings. 10° fixed tilt systems were seen to potentially benefit the most from ARCs, while single axis trackers benefitted the least.