Expansion of the mechanical sub cell model with interface parameters provided by mechanical testing

Abstract

The reliability and durability of PV modules has become increasingly important to further reduce the overall cost of PV. A thorough understanding of the thermo-mechanical phenomena that influence the reliability will provide new insights to further optimize the lifetime of imec’s module technologies. To progress towards the multiscale finite element model it is suggested that important details need to be added to the finite element model. The previous model simulated the four-point bend boundary conditions and will be extended to include interface parameters. Interfaces are of major importance since the weakest links in interconnected solar cells are usually located near an interface e.g. the interface between the solder joint and the wire which can be measured by peel tests in terms of adhesion strength. The simulations and measurements will enable further optimisation of imec’s module technologies and will mainly provide more information on built-in stress relief when using imec’s multi-wire bifacial interconnection. To achieve goals stated above, the simulation model which incorporates bulk mechanical behavior of a sub-cell will be extended with interface parameters provided by additional mechanical measurements. Depending on the outcome of this model the interaction between sub-cells can be demonstrated. The simulation model will be applied to industry standard cell technologies with printed contacts, with a possible extension towards cells with plated contacts.