Numerical homogenization of poly-crystalline silicon wafer based photovoltaic modules including pre-cracks

Abstract

The photovoltaic (PV) modules containing multiple polycrystalline silicon solar cells (PSSCs) are one of the most common devices for solar energy production. PSSCs are finding different applications such as on buildings and on solar-driven airplanes, hence, their mechanical analyses are required. During the lifespan of PSSCs, the performance degrades, which is predominantly associated with the cracking of the crystalline silicon wafer (PSW). Moreover, because of the multiple materials involved and the complicated microstructure of the energy-producing component, polycrystalline silicon wafer (PSW), modeling becomes computationally expensive. Therefore, model reduction techniques, such as homogenization, are needed. The mechanical response of polycrystalline silicon solar cells (PSSCs) is investigated in this work. The crystalline patterns of the PSW were generated using a Voronoi-tessellation scheme. A mean-field homogenization scheme using the finite element (FE) method was employed to predict the homogenized response of the PSSCs. The response of the PSSC with heterogeneous and homogeneous modeling was compared. The stiffness degradation due to the existing microcracks of the PSW was investigated. It is evident from these investigations that the homogenized FE solution provides an accurate and computationally efficient representation of the progressive failure in solar cells. The approach presented here offers a basis to further enhance the knowledge of failure analysis in PV modules and quantify the subsequent degradation of their energy producing capacity.