| Work Detail |
Polish researchers have assessed how textured glass used as a front cover for building-integrated photovoltaic panels affects performance. They found that energy efficiency could be up to 5% lower than that of modules based on conventional glass, with reflection parameters of up to 88% in the visible region.
Scientists from the John Paul II Catholic University in Lublin (Poland) have analysed the optical and electrical parameters of textured glass in building-integrated photovoltaic (BIPV) systems and found that this type of glass can significantly affect photovoltaic power generation and increase light reflection.
“In the case of installations in urban spaces, an important parameter is the low reflectance value and, consequently, the reduction of light reflections that can blind drivers,” says the lead author of the research, Pawel Kwasnicki. “As BIPV is becoming more and more popular, expanding the scope of installation on facades, building walls and various types of glazing, its aesthetic aspects become one of the key parameters.”
Textured glass is made by heating glass sheets, softening them, and then passing them through etched rollers. For their research, the researchers used two commercially available sheets of textured glass. The first sample had a surface topography with height differences of 45 µm, while the second was in the range of 10 µm. Sample 1 had a regular pattern, with features with a diameter of 400 µm, while in the case of sample 2, the pattern was irregular, with objects ranging from 50 µm to more than 1 mm.
In total, three modules were built: one with sample 1, one with sample 2, and the last with clear reference glass. In all cases, a lamination sheet was placed between the glass and the cell, which measured 2.89 W encapsulated. The fill factor of the bare cell was measured at 71%, its open circuit voltage at 0.699 V, and its short circuit current at 5.83 A.
“From the calculation, the direct solar absorbance value for the reference sample was almost 13 and 5 times lower than that of samples 1 and 2, respectively,” the researchers say. “For both textured samples, the transmittance was significantly lower in the near-infrared (NIR) region than that of the reference glass. Moreover, for the sample with a regular surface pattern (sample 1), a slightly lower transmittance was observed in the infrared (IR) region compared to the non-regular one (sample 2). A significantly lower reflectance was measured in the visible light (VIS) region: 8.5x lower for sample 1 and 1.6x for sample 2.”
In terms of electrical performance, the reference cell measured a peak power of 2.86 W, Sample 1 2.79 W, and Sample 2 2.74 W. The fill factor, open-circuit voltage, and short-circuit current of the reference module were 72.4%, 0.73 V, and 5.425 A, respectively. Sample 1 had 72.9%, 0.727 V, and 5.27 A, while Sample 2 had 73.2%, 0.728 V, and 5.143 A.
The analysis showed that the energy efficiency of modules using textured glass could be up to 5% lower than that of modules based on conventional glass, with reflection parameters of up to 88% in the VIS region.
“Since infrared radiation has several negative effects on silicon PV cells, including limited energy absorption, thermal effects leading to reduced efficiency, material limitations, and optical losses due to carrier recombination, the application of textured glass in PV modules is cost-effective,” the academics conclude. “Moreover, prolonged exposure to IR radiation can accelerate material degradation, affecting the stability and lifetime of PV modules.”
Their findings were presented in “ Texturized glass in the application of architectural photovoltaics,” published in Cleaner Engineering and Technology . In addition to the John Paul II Catholic University of Lublin, Kwasnicki is affiliated with the Polish photovoltaics provider ML System. |
