Bifacial single glass encapsulation of solar module – An effective solution to enhance reliability via breathability

Abstract

Outdoor performance of PV modules encapsulated with two different approaches showed that annual power generation of single glass solar modules was higher than that of double glass solar modules (0.32 % higher in terms of average annual per watt power generation gain) and annual power degradation of single glass solar modules was lower than that of double glass solar modules (1.07 % vs 1.47 %, respectively). The reason was attributed to the breathability of PV modules, which was demonstrated by many qualitative and quantitative experiments, including: 1) color change/reaction of cobalt chloride (CoCl₂) test paper (entrapped between encapsulant and backsheet) with water diffused into PV module; 2) water content of encapsulant after aging; 3) acetic acid concentration inside encapsulant after aging. Due to its unique structure, single glass PV module can “breathe” under daily operation which enables small molecules, e.g., water, medium sized molecules, e.g., acetic acid, diffuse out from the PV module, reducing continuous corrosion of metallic components of PV modules. Breathability ensures PV module higher reliability as well as high efficiency by removal of water and acetic acid and eventually results in more annual power generation. Breathability can mitigate the risk of failure of the PV system, which was demonstrated by using failure mode and effect analysis (FMEA) approach.