A multi-physics and multi-scale numerical approach to microcracking and power-loss in photovoltaic modules

Abstract

A multi-physics and multi-scale computational approach is proposed in the present work to study the evolution of microcracking in polycrystalline Silicon (Si) solar cells composing photovoltaic (PV) modules. Coupling between the elastic and the electric fields is provided according to an equivalent circuit model for the PV module where the electrically inactive area is determined from the analysis of the microcrack pattern. The structural scale of the PV laminate (the macro-model) is coupled to the scale of the polycrystals (the micro-model) using a multiscale nonlinear finite element approach where the macro-scale displacements of the Si cell borders are used as boundary conditions for the micro-model. Intergranular cracking in the Si cell is simulated using a nonlinear fracture mechanics cohesive zone model (CZM). A case-study shows the potentiality of the method, in particular as regards the analysis of the microcrack orientation and distribution, as well as of the effect of cracking on the electric characteristics of the PV module.

A user-defined finite element for laminated glass panels and photovoltaic modules based on a layer-wise theory

“…(6), N K denotes the membrane force tensor of the Kth layer, Q K is the shear force vector, and M K represents the tensor of bending and twisting moments. Following [20], the equilibrium conditions for the layers can be formulated as follows:…”

“…Crystalline or thin film photovoltaic modules currently available on the market are composed from front and back glass or polymer layers and a solar cell layer embedded in a polymeric encapsulant [4][5][6]. A lightweight design of photovoltaic modules includes front and back panels made from plastics.…”

A Generalized Electric Model for Mono and Polycrystalline Silicon in the Presence of Cracks and Random Defects

“…1(b)). According to this pure geometrical criterion which does not take into account neither physical mechanisms such as thermo-mechanical deformation, nor the fact that the cells are embedded in the composite PV module, worstcase scenarios have been predicted by considering all the experimentally detected [2] or numerically simulated [7] cracks as perfectly insulated lines. In reality, it is reasonable to expect intermediate configurations where cracks may partially conduct depending on the relative crack opening displacement at crack faces [8].…”

A geometric approach for PV modules degradation

“…However, when cell regions are isolated or inactive, the photo-generated current I SCcracked and the recombination current (I 01cracked and I 02cracked ) will decrease respecting the following equations [7,10]:…”