Erik Peter

Mechanical problems of novel back contact solar modules

In this paper, the mechanical integrity of interconnect structures of different types of photovoltaic modules is analyzed by FEM-simulations. The goal is to develop a theoretical framework for the systematic understanding of mechanical behavior of photovoltaic modules. The results of this investigation figure out, where are critical locations in the photovoltaic module assembly that limit the module lifetime. Another goal is to show, how changes in the assembly technology (e.g. geometries, processes, materials) will have an effect on the overall reliability of the photovoltaic module. FEM-Simulations were carried out, in order to analyze the mechanical stresses, which were built up during the operation of the photovoltaic modules. Thermo cycling test between -40°C and +80°C were simulated. These tests are used in the qualification procedure for photovoltaic modules according to TEC/EN 61215. The results of the study show that stresses during the assembly and the operation occur in different locations in dependence of the assembly design. Tn the traditional modules the silicon underneath the busbar and the copper ribbon crimp between two adjunct cells are the locations where most of the damage is likely to accumulate. In contrast to this the solder joints in the outermost row of the back contact cells are the critical locations in the novel back contact design. The paper will explain the differences of thermo-mechanical behavior between the designs.

Harsh environment application of electronics – Reliability of copper wiring and testability thereof

Abstract Harsh environment imposes different and more severe operational demands to electronic devices. Besides loads as temperature and vibration, also chemical loads in contact to electronics, can lead to new types of failure, e.g. by corrosion. With regard to reliability demands, testability thereof becomes more and more important. This implies activation energies for copper corrosion, which were determined. A model is proposed in order to gain more understanding of the ongoing chemical processes between the electronic control unit and transmission fluid.

Enhancing the lifetime prediction methodology for photovoltaic modules based on electronic packaging experience

Photovoltaic modules as well as automotive electronics are both designed to perform more than 20 years in the field. They show many similarities, for example the material combinations (Silicon, copper, lead free interconnection), the field loads, qualification tests, etc.