Enhancement of electrical performance of c-Si PV modules through optimized soldering process

Soldering techniques used to interconnect large thin c-Si solar cells in PV modules have a significant impact on the generated electrical power and reliability of the manufactured modules. Poor soldering process results on an abnormal mechanical or thermal stress which leads to micro cracks, cell breakage, and lower adhesion force. Moreover, poor soldering increases the contact resistance (R_c) between the busbar and ribbon and lowers the fill factor (FF) of the PV module. In this paper, the impact of process parameters in an automated induction soldering process has been examined. Different adhesion force (AF) profiles and relationship with current transport mechanism have been investigated. AF is increased with temperature till 240-260°C whereas it is lowered at low and very high soldering temperature. Electroluminescence (EL) image showed that solar cell is prone to micro-cracks at higher temperature but observed as a random event. Modules were processed with different soldering conditions and characterized. Results show that, using the suggested soldering process, FF can be improved by 0.53, and the power output can be as high as 251.26 W, which is higher by 2.50% compared to the non-optimized process.