Study of photovoltaic (PV) module interconnections failure analysis and reliability

A thesis submitted in partial fulfilment of the requirements of the University of Wolverhampton for the award of Doctor of Philosophy.Solar Energy is one of the most widely used renewable energy sources, with the solar Photovoltaic (PV) module technologies deployed as one of the primary renewable energy sources to replace fossil fuels. However, the R&D challenge for improving the performance and reliability of PV modules has become an urgent and critical agenda for the energy generation industry sector. The interconnection between the solar PV cells is a very important part of the PV module assembly, and its failure can adversely affect the performance and reliability of the PV module. The interconnection failure has been mostly linked to the crack initiation and propagation in the solder joints used to connect the ribbon interconnection to the cell. This research focuses on the study of the thermal failure of PV module solder joint to determine the optimum ribbon interconnection designs that will give improved thermo-mechanical reliability. It develops a virtual reliability qualification process for the assessment of the life expectancy of PV module interconnections. The FEM simulations in ABAQUS 2019 software are implemented to investigate failure of the solder joints in different ribbon interconnection designs under anticipated life cycle loading conditions and high temperature lamination process. For the first time, the extended finite element method (XFEM) technique is used to determine the crack initiation temperature, crack location, direction and growth rate in solder joint of PV module interconnection under lamination process. Furthermore, the research used the Developed Morrow Energy Density lifetime model to determine the number of cycles to creep-fatigue failure, and then it defined a new generic exponent factor using the Coffin–Manson–Arrhenius model to estimate the lifetime for the designs under different thermal cycling conditions. The research also combines the numerical results of XFEM and creep-fatigue investigation to determine the failure lifetime of PV Module interconnection designs. The results show that the Multi-Busbar interconnection design improves solder joint creep-fatigue life (up to 15%) and consequently provides higher thermo-mechanical reliability for the solar PV modules compared to other studied designs (Conventional and the Light Capturing Ribbon interconnections). The results of this PV module interconnections study can be used for evaluating potential design changes and to facilitate design for reliability validation of different configurations for improving the long-term PV module system reliability.Faculty of Science and Engineering, University of Wolverhampton