Effect of Glass Beads on the Solar Optical Properties of Thermoplastic Encapsulants for Colored PV Modules

A promising approach for producing colored photovoltaic (PV) modules is the incorporation of interference pigments into the front encapsulant. Besides several advantages such as spectrally selective reflection, higher efficiency or better durability, the main disadvantage of interference pigments are variations in specular reflectance depending on the angle [1]. The main objective of this work was to evaluate the potential of glass beads as diffusor pigments in colored PV encapsulants. Films varying in type (refractive index and particle size) and concentration of the glass beads were manufactured. Furthermore, films with a combination of glass fillers and interference pigments were analysed. Fourteen film grades were assessed by UV/Vis/NIR spectroscopy. The reflectance of the glass bead modified encapsulants was dependent on the refractive index and the particle size. The smallest beads with the highest reflectance index were not suitable. The transmittance of the film was below 80 %. However, the other glass grades were classified as an interesting option for homogenization fillers for colored PV encapsulants.