FEM simulation of influence of different polymeric module materials and layouts on thermomechanical deformations in strings of shingled solar cells

Among several new module concepts and cell architectures, shingled solar cell interconnection is a promising technology to realize increased power output (higher power densities) by increased active cell area and low electrical losses. The direct interconnection by a slight overlapping of solar cells, using electrically conductive adhesive (ECA) asjoint material, requires a sound understanding of the loads the ECA joint faces during module lifetime. The ECA joint not only has to enable electric conductivity but at the same time needs to compensate different mechanical responses of the materials in the module laminate due to varying external stresses induced by variations of temperature and mechanical loads deflecting the module, e.g. wind or snow covering the modules. Especially thermal effects on the structure of solar panels are significant and complicated due to differing coefficients of thermal expansion (CTE) of the materials in use. However, the influence of anisotropic and also possibly negative coefficients of thermal expansion on thermomechanical stresses in string of shingled solar cells has not yet been investigated. Therefore, the current work aims for a more realistic representation of the thermomechanical behavior of photovoltaic (PV) modules by considering the anisotropy of the CTE of polymer films.