Measurement and modelling of water ingress into double‐glass photovoltaic modules

Abstract

Polymer encapsulants are an essential component in photovoltaic (PV) devices, providing mechanical support, optical coupling, and electrical and physical isolation. However, moisture ingress into the module can degrade these polymers and subsequently the performance of the device. In this paper, we report experimental measurements of the temporal evolution of moisture content in ethylene‐vinyl acetate (EVA) encapsulant in a double‐glass PV module. Using physical properties of EVA as determined by water vapour transmission rate measurements, we simulate diffusion of water into the module using a finite element model. The model accounts for realistic geometry of our module and is used to simulate accelerated test conditions and outdoor operation in geographic locations. Using the calculated results, we propose two schemes using the accelerated test results to understand the behaviour of modules operating in humid climates. Finally, we show that the time needed to reach the saturation water concentration can be increased by as much as a factor of two by reducing the initial water content in EVA films.

35 years of photovoltaics: Analysis of the TISO‐10‐kW solar plant, lessons learnt in safety and performance—Part 2

“…So that a high-quality EVA formulation, or different encapsulant, would be required. 24 With their quite solid module sealing, we can speculate that the lessons learnt on the long-term performance of the Arco-Solar modules investigated in this work may be more easily replicable (and transferable), to a certain extent, to the performance of glass/glass structures, rather than to the performance of conventional modules with glass/foil structures.…”

“…On the other hand, using EVA, so far the preferred choice by the industry due to its low cost, a potential drawback of glass/glass structures is that the acetic acid generated by photo‐degradation will not be released into the atmosphere, remaining trapped in the module sandwich, and potentially impacting module performance in the long run. So that a high‐quality EVA formulation, or different encapsulant, would be required …”

A multifield coupled thermo‐chemo‐mechanical theory for the reaction‐diffusion modeling in photovoltaics

“…Despite the advantages and strengths, the PV modules are sensitive to moisture diffusion as well as chemical reactions, especially in hygrothermal outdoor environments, 4–8 and thus its reliability is not still very competitive. A great deal of research has been focused on investigating the degradation mechanisms, see References 9–16, among many others, and most of them studied the diffusion phenomena at the constant temperature and humidity conditions. However, the realistic evaluation of PV durability is very challenging due to the coupling between the reaction‐diffusion and thermo‐mechanical problems and requires a multiphysics framework to comprehensively study the different failure mechanisms under changing environments 17–21 …”