Comparative Optical Analysis of Imprinted Nano-, Micro- and Biotextures on Solar Glasses for Increased Energy Yield

In modern photovoltaic (PV) systems such as bifacial and building-integrated PV, a big share of sunlight impinges at large incident angles on the air-to-glass module interface. These designs exceedingly call for effective omnidirectional antireflective (AR) measures. Texturing of PV cover glasses can effectively mitigate reflection losses in a broad spectral and angular range. Numerous individual textures have been presented in the literature; however, the lack of consistent material stacks hinders a comparative evaluation. Herein, UV-nanoimprint lithography is used to fabricate and analyze 12 different artificial and bioreplicated textures from nano- to mesoscale on glass. The angle-resolved reflectance is examined for incident angles from 5 degrees to 80 degrees and analyzed the scattering properties. For example, the effect of the investigated textures on the annual energy yield is calculated for a tilted bifacial PV module located in Berlin, Germany. While well-known moth-eye nanostructures exhibit excellent AR behavior near-normal incidence, their shallow angle performance is often not reported. The best-performing textures exhibit features on microscale and a large surface enhancement factor, increasing the annual energy yield up to 5% when compared to nontextured devices. The results give clear design guidelines for textured glasses of future PV applications.