CdTe solar cell performance under low-intensity light irradiance

Abstract

Study of the device characteristics of a CdTe solar cell under weak light irradiance (Eirra) is important both for the understanding of the fundamental device physics and for the commercial application, where Eirra with intensity much less than one sun is often encountered for an outdoor solar cell module. In this study, CdTe solar cell performance under Eirra as low as 0.015sun was studied. Both the fill factor (FF) and the open-circuit voltage (Voc) were found to be critically affected by the shunt resistance at low Eirra. The current shunting depends critically on the physical location of the shunting paths in the CdTe absorber layer. Space-charge limited current (SCLC) was identified to be an important contribution to the shunting current in thin film CdTe solar cell. At an Eirra as low as 0.015 Sun, CdTe solar cell with a high shunt resistance maintained an efficiency of ~70 to 80% of the value tested at the standard AM1.5 Eirra. The experimental results showed that polycrystalline CdTe thin film solar cell is a good photovoltaic device for electric power generation at low Eirra. This study provides constructive guidelines for the future design and fabrication of CdTe solar cells.