A coupled thermo-electro-mechanical model for fracture in solar cells

Damage, micro-cracks, grain boundaries and other defects in solar cells are impacting on the electric power-loss and lifetime of photovoltaic modules, a complex example of a laminate structure. In the present contribution, a one-dimensional model for simulating the electric current distribution in solar cells accounting for a distributed series resistance is generalized to the presence of partially conductive cracks. The proposed model is used to perform a quantitative analysis of electroluminescence (EL) images of cracked monocrystalline silicon solar cells. A further generalization in a stochastic direction is also proposed in order to take into account randomly distributed defects typical of polycrystalline silicon. These developments represent a fundamental step towards the realization of an innovative fully coupled thermo-electro-mechanical numerical method for the study of fracture in solar cells and assessing the durability of photovoltaics.