Residual Stress Analysis and Bow Simulation of Crystalline Silicon Solar Cells Induced by Firing Process

• Main Authors: Chih-HungChen, 陳志宏
• Other Authors: Hsuan-Teh Hu
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/av6xgg

博士 === 國立成功大學 === 土木工程學系 === 104 === In this thesis, a systematic approach for simulating the cell bowing induced by the firing process is presented. This approach consists of three processes: (1) the material properties are determined using a nanoidentation test; (2) the thicknesses of aluminum (Al) paste and silver (Ag) busbars and fingers are measured using scanning electron microscopy; (3) Non-linear finite element analysis (FEA) is used for simulating the cell bowing induced by the firing process. As a result, the bowing obtained using FEA simulation agrees better with the experimental data than that using the bowing calculations suggested by Huster and Hilali. Bow simulation of single crystalline silicon (sc-Si), cast, and edge-defined film-fed growth (EFG) multi-crystalline silicon wafer of different thickness is presented. The influence of different silicon wafer for cell bowing is not obvious. When the thickness of Al-paste increases, the bowing induced by the firing process increases. Conversely, the increasing thickness of Ag busbar and fingers makes the decreasing bowing. It is also proposed that the metallization pattern, Ag busbars and fingers screen printed on the front of a solar cell, can be designed using this approach. A practical case of a 3-busbar Si solar cell is presented. In addition, the total in-plane residual stress state in the wafer/cell due to the firing process can be determined using the FEA simulation. A detailed analysis of the firing-induced stress state in single crystalline silicon (sc-Si), cast, and edge-defined film-fed growth (EFG) multi-crystalline silicon wafers of different thicknesses is presented. Based on this analysis, a simple residual stress calculation is developed to estimate the maximum in-plane principal stress in the wafers.