Influence of Thickness Deviation on crystalline Silicon Solar Cell Performance

This paper presents a novel method to measure the local thickness of silicon wafers spatially resolved. A camera detects the transmission of infrared radiation through a silicon wafer, which transforms to a local thickness map. Experiments with String Ribbon solar cells show that the local contact resistance depends on the local wafer thickness. The high resolution thickness map is therefore transformed into a local contact resistance map. A 3D-multi-diode array models the efficiency loss due to an inhomogeneous contact resistance. The fill factor loss ΔFF due to the thickness deviation of solar cells amounts up to ΔFF = -1%abs, or an efficiency loss Δη = -0.2%abs.