The Impact of Reflectance Variation in Silicon Heterojunction Solar Cells and Modules on the Perception of Color Differences

Abstract

The color produced by visible light that reflects from the photovoltaic modules can influence visual aesthetics for colored photovoltaic applications, such as the building integrated photovoltaic and the vehicles integrated photovoltaic. How two colors lying close together can be perceived by the human eye is important for aesthetic design. In this article, we investigate the reflectance spectra variation caused by the variation of indium tin oxide thickness and incidence angle of sunlight based on the well-known silicon heterojunction solar cells and modules. By converting the reflectance spectra into the Delta E 2000 value, we quantify whether differences in color can be perceived. The colors are also predicted based on the standard red, green, and blue color space. The results show that the reflectance variation because of an ITO thickness deviation of 5 nm in SHJ solar cells leads to a perceptible color difference, which can be suppressed after encapsulation but is still perceptible on close observation. The ITO thickness deviation should be controlled within 3 nm to produce a nearly imperceptible visual appearance. The color difference of SHJ modules with an ITO thickness of 70 nm is nearly imperceptible if the incidence angle is below 70°. For comparison, the color differences of the passivated emitter and rear contact solar cells using SiNx as an antireflection layer is also investigated.