Analysis of the Annual Performance of Bifacial Modules and Optimization Methods

TLDR

Bifacial modules capture sunlight from front and rear, producing more energy than monofacial modules, but their performance depends on the spatial distribution of rear irradiance affected by albedo, reflective surface size, module elevation, and tilt angle. The study investigates the individual and combined effects of albedo, reflective surface size, module elevation, and tilt angle on the annual energy yield of south‑facing bifacial modules at two contrasting sites. Simulations were performed at two sites with opposite climates to model these dependencies and suggest optimal positioning of bifacial modules. After optimizing tilt angle, albedo, and module elevation, the annual yield increases linearly with albedo, saturates with reflective surface size, rises with module elevation up to a point, and under optimal conditions bifacial modules can produce up to 25 % more energy than standard modules.

Abstract

Bifacial modules have the advantage of capturing sunlight from front as well as from rear surfaces, and therefore, they are able to produce larger amounts of energy, compared with standard (monofacial) modules. However, their performance depends on the spatial distribution of the irradiance incident on the rear module surface, which is strongly affected by several site-specific conditions, such as albedo, reflective surface size, module elevation, and tilt angle. In this study, we elaborate upon the individual and combined effects of these factors on the annual energy yield of stand-alone south-facing bifacial modules through simulations at two site locations with contrary climatic conditions. Following the optimization of the tilt angle of bifacial modules dependent on the site, albedo, and module elevation, we demonstrate that the annual energy yield of a bifacial module increases linearly with albedo, which shows a monotonically increasing but, in addition, saturating behavior versus reflective surface size, and increases up to a certain module elevation. Through the simultaneous consideration of these dependences, we suggest an optimal positioning of bifacial modules. Finally, we show that under these optimal conditions, bifacial modules can supply up to 25% more energy compared with standard modules.