Stress and strain within photovoltaic modules using the finite element method: A critical review

Simulation tools are increasingly employed towards quantifying the lifetime of photovoltaic (PV) modules while providing valuable insights into the various failure modes. The use of the finite element method (FEM) in this regard has been especially popular because of its flexibility and the ability to quantify stress levels for a large variety of scenarios ranging from process-induced stress up to field conditions. The thermo-mechanical behaviour of the module or its components is often considered due to the link with common field failures such as cell cracks, interconnection failures, glass fracture, delamination and many others. However, the approaches used, the various inputs considered and the obtained results are highly scattered and sometimes conflicting. This work provides a structured review of the reported simulation approaches and resulting insights obtained through thermo-mechanical finite element simulations on commercial as well as novel PV module technologies. The influence and validity of various inputs such as the used material models, boundary conditions and other assumptions are discussed. Learnings and best practices can be leveraged by future simulations to expand on and accelerate the design-for-reliability capabilities of finite element models for PV modules.