Photovoltaic modules of crystalline solar cells using a new type assembly structure

Abstract

This paper presents the performance and the reliability of photovoltaic (PV) modules of single 5 inch crystalline solar cells using a new type assembly process with epoxy-based conductive adhesive (CA). The assembly structure of the solar module is characterized by its isolation design between p-n junction borderline. Since soldering technology is the main process in interconnecting crystalline solar cells in photovoltaic industry production, a conventional counterpart of Sn-Pb soldering was also conducted for comparison purpose in this work. Compare the power output data before and after interconnecting process of the solar devices, it is estimated that the solar cell power increased with epoxy-based conductive adhesive and Sn-Pb solder are 6.36% and 4.62%, respectively. Performance of the epoxy-based conductive adhesive sample was due to high electrical conductivity of the silver element comparing to the Sn-Pb solder material. High temperature soldering process resulted bowing effect of the solar cell and causing cell breakage when lamination. A thermal cycle endurance test based on IEC 61215 standard was carried out for long term performance characteristics. In general, solar modules' power loss increased with cycling times. It was drawn that the power loss of solar CA sample (3.98%) was lower than that of soldering sample (5.62%) after 200 thermal cycle times. In addition, the CA sample exhibited a high shunt resistance (Rsh) property (106.92Ohm) than that of soldering sample (102.32Ohm), it indicates that the CA sample is more stable than soldering sample after interconnecting process. The Rsh of soldering sample decreased from 102.32Ohm to 3.02Ohm and that of CA module decreased from 106.92Ohm to 4.390hm, it indicated that the performance of CA module was more stable than that of soldering sample.