High Efficiency Copper Electroplated Heterojunction Solar Cells and Modules – The Path towards 25% Cell Efficiency

Abstract

In this work, we present the latest results from Kaneka on high efficiency heterojunction crystalline silicon (c-Si) solar cells with a copper metallization scheme. We report copper plated heterojunction c-Si solar cells on 6 inch c-Si Cz wafers with a world record conversion on efficiency and generated power. Efficiencies of 24.2% (aperture area) and powers of 5.64 W (total area measurement) at 1 sun STC measurement have been certified by an independent laboratory. Values of open circuit voltage above 745mV, values of short circuit current above 40 mA/cm2, and values of fill factor above 82% have been reached. Results of the impact of the silicon wafer thickness on the efficiency of heterojunction c-Si solar cells are presented. Damp heat and thermal cycling reliability data of the copper electroplated heterojunction show comparable performance with Ag printed heterojunction. Temperature coefficient of -0.23%/ºC has been achieved which will translate in a higher total power of these devices under outdoor operation. We present the path toward efficiencies above 25% for low concentrations which combined with the good temperature coefficient show the potential of heterojunction technology for LCPV applications in warm climates.