Modeling And Simulation Of The Process For Germanium Based Solar Cell In Parallel Gap Resistance Welding

Solar cells have got more and more attention since they were applied in the spacecraft from 1958. Compared with traditional silicon solar cells, germanium substrate solar cells have become a major power spacecraft because of their high conversion efficiency, anti-space radiation resistance, good temperature characteristics and long life. However, the technology of parallel gap welding for germanium substrates solar cells just started with the uneven quality of welding products. In actual production process, it is not wise to select a reasonable welding process through a large number of experiments considering the long cycle test and the high cost of rare metal coating. As a result, finite element analysis has been used for germanium-based solar cells in parallel gap resistance welding in this paper.First of all, model of parallel gap resistance welding process for the solar cell is simplified according to the practical situation. A reasonable model of the solar cells in parallel gap resistance welding was established through adjusting the contact resistance model. The temperature field and the resistance model for the solar cells in parallel gap welding are obtained through thermoelectric coupling analysis. It is concluded that increasing electrode separation gap will increase the separation trend of high temperature region, and the shift of electrodes make the center of high temperature shift in the same side.Secondly, finite element model of single-interconnect plate solar cell is established based on finite element analysis of the specimen in parallel gap resistance welding. Parallel gap welding process for single-interconnect solar cells is analyzed through thermal-current-structure coupling simulation. The effects of different parameters for solar cells are studied through changing the parameters of welding technology. It is concluded that the thickness of interconnect plate and coating scarcely influent on solar welding process, and the increasing of heat input not only increases the welding temperature but also the welding deformation.Finally, different welding orders of the welding process of solar cell for optimization of welding order are compared. Studies have shown that distribution law of the temperature field and stress field is almost the same, but not the deformation. In other words, welding order has little influence on temperature and stress field, but not the same in post weld deformation. The optimal welding sequence is obtained according to the measure of the smallest displacement.In this paper, the numerical simulation analysis of parallel gap resistance welding for germanium-based solar cells is carried out combining with experimental and simulation method. Optimum process scheme is obtained through comparing the temperature field, stress field and deformation distribution. It is provided a theoretical basis for manufacturing of germanium-based solar cells.