A research team in China has developed a periodic groove glass structure to improve light capture in facade-mounted PV modules. The proposed design was found to reduce reflection at high incidence angles while maintaining compatibility with large-scale glass manufacturing.
Researchers in China have designed a new type of cover glass featuring a periodic groove pattern that enhances the amount of light captured by photovoltaic modules installed on building facades. According to the study, the newly proposed glass design lowers light reflection at steep angles of incidence while remaining suitable for existing large-scale glass production methods.
A research group headed by the Harbin Institute of Technology in China introduced the innovative cover glass for facade-mounted PV modules to reduce reflection losses when sunlight strikes the surface at high incidence angles. The design incorporates a periodic groove configuration that was optimized using the constrained optimization by linear approximation (COBYLA) algorithm together with ray-tracing simulations carried out in Comsol Multiphysics.
“Existing antireflective technologies for glass could not address the issue of high reflectivity on photovoltaic-module glass surfaces under large-angle-of-incidence (AOI) conditions,” the researchers said. “Therefore, it remained a significant challenge to design a high-performance light-trapping structure that reduced reflectance at the air/glass interface over a broad incidence range of 0° to 89°, particularly at angles between 70° and 89°, while remaining suitable for the rolling process.”
To refine the groove geometry, the researchers employed the COBYLA optimization algorithm, adjusting design variables such as groove depth, width, height, and the angles of individual segments. COBYLA is a numerical optimization technique that solves constrained problems by repeatedly refining an approximate linear representation of the objective function. The approach is commonly applied in situations where derivatives are unavailable or difficult to compute.
The optimization process aimed to achieve the lowest possible average reflectance across wavelengths spanning 400 nm to 1,050 nm while considering angles of incidence from 0° to 89°. After determining the optimal groove structure, the team verified its performance using three-dimensional optical simulations of a crystalline silicon photovoltaic module. They also examined the design's resilience by modifying groove dimensions and internal angles to evaluate whether the antireflective characteristics would remain effective despite manufacturing tolerances.
“The numerical results were very promising,” the researchers said. “Within a wavelength range of 400 nm to 1,050 nm, the average reflectance of the air/groove-structured glass interface remained below 2.4% for AOIs of up to 60°, while the maximum reflectance was only 12.6% at an AOI of 89°.”
Simulation results indicated that when the light-trapping glass was incorporated into a crystalline silicon PV module, spectral absorption increased by 12% at an angle of incidence of 70° and by 73% at an angle of incidence of 89%, compared with photovoltaic modules fitted with conventional flat glass.
The researchers explained that the selected structural characteristics, including a 0.76 aspect ratio and a smooth cross-sectional contour, were chosen to provide an effective compromise between optical efficiency and practical manufacturability.
“Simulation results on the effects of scaling and geometric variations indicated that this light-trapping structure retained its superior performance under moderate linear scaling and internal segment-angle perturbations,” the team concluded. “These results indicate that the structure has significant potential to support the wider deployment of photovoltaic modules on building facades and to be compatible with existing large-scale PV cover-glass manufacturing processes, including rolling.”
The research was published in Results in Engineering under the title “High-efficiency periodic groove structured glass with broad angle antireflection for facade-mounted photovoltaic modules.” The study was carried out by scientists from China's Harbin Institute of Technology together with Shenzhen Yongxing Technology.
Originally reported by pv magazine on Jul 21, 2026.
