A Bifacial View Factor Model Considering Terrain Slope and Nonuniform Albedo

Abstract

Simulation models used to develop and finance bifacial photovoltaic systems estimate rear-side irradiance using 2-D view factor models. These models make simplifying assumptions that do not account for complexities - such as sloped terrain and nonuniform ground albedo - found in modern photovoltaic systems. In this work, we describe ANTS-2D, a new, computationally efficient 2-D view factor model for computing front- and rear-side irradiance across the module surface, considering both nonuniformity in ground albedo and sloped terrain. For the base case of a horizontal and uniform ground surface, we show that the model's accuracy relative to a ray-tracing model baseline is within approximately 1 W m-2 of the best available alternative view factor model while also featuring an 85% reduction in computation time. The model also allows for detailed ground irradiances, particularly useful for agrivoltaic applications.