MECHANICAL AND ELECTRICAL CHARACTERISATION OF THIN MULTI-CRYSTALLINE SILICONSOLAR CELLS

摘要

One of the key issues for future industrial solar cell production is the use of wafers with reduced thickness and enlarged area. The current standard thickness for industrial solar cells is between 260 μm and 330 μm and there is a general trend towards 200 μm thick wafers. Mechanical wafer stability strongly decreases with wafer thickness, ranging in a Twist-Test from 9.2 Newton for 330 μm thickness down to 1.9 Newton for 150 μm. Tocompare the stability of as-cut material with surface treated wafers, the mechanical stability after alkaline etchingand isotropic texturing was determined for wafers of different thicknesses. Wafer material thickness has a stronginfluence on solar cell parameters. Our measurements show a drop in efficiency of almost 1% for 150 μm thickwafers when compared with 330 μm thick wafers. With the bending measurement, a slope could be calculated fromthe data that predicts the fracture force in a very early measurement state. To guarantee that the wafer material is notdamaged by the stability measurement, cycling tests with different mc-wafers were performed. The results on fourdifferent materials showed no influence of the measurement method on the mechanical stability.