Analysis of the Thermal Stress for Combined Electrode of Soldered Crystalline Silicon Solar Cells under Temperature Field

He Wang,Ao Wang,Dengyuan Song,Hong Yang

doi:10.1155/2016/5306925

Abstract

Based on the theory of material mechanics and thermal stress analysis, the stress distribution of combined electrode for crystalline silicon solar module was studied for the first time. The shear stress and normal stress distribution of soldered structure for crystalline silicon solar cells under the thermal field were discussed. And the results show that the stress distribution is not simply linear relationship as some results found. But there is a stress concentration at the edge, which was considered as the true reason that caused microcracks at the edge of soldered solar cells. The conclusions we got in this paper provide a theoretical basis for deceasing the breakage rates of soldered crystalline silicon solar cells and improving the reliability of crystalline silicon solar modules.

Highlights

Crystalline silicon solar cells have become the main force of the photovoltaic industry
In the process of crystalline silicon solar modules production, the cells of PV modules are electrically connected in series by interlacing tin-coated copper ribbon
Due to the large difference of the coefficient of thermal expansion (CTE) between metal and silicon, thermal stress of such combined electrode will appear and accumulate in the metallization interconnection system when the PV module is suffering from a temperature cycle

Summary

Introduction

Crystalline silicon solar cells have become the main force of the photovoltaic industry. Crystalline silicon solar module is the critical component of photovoltaic (PV) generation system. The cyclic thermal stress will cause microcracks and voids, which will increase the contact resistance of the electrode and reduce PV modules’ lifetime. Many researches on module reliability have been done [4,5,6,7], there was no quantitative research for the thermal stress distribution of combined electrode inside the crystalline silicon solar module. A model of the thermal stress distribution of combined electrode for crystalline silicon solar module is established for the first time. The shear stress and normal stress distribution of soldered structure for crystalline silicon solar cell under the thermal field were discussed. There is a stress concentration at the edge, which was considered as the true reason that caused microcracks at the edge of the soldered solar cell

Structure Model of Combined Electrode for Crystalline Silicon Solar Cells

Solution and Analysis

Findings

Conclusions