In Situ Observation of the Degradation in Multi‐Crystalline Si Solar Cells by Electroluminescence

Abstract

Carrier‐induced efficiency degradation of multi‐crystalline Si (mc‐Si) solar cells is studied in situ by detecting the electroluminescence (EL) from the cells. Series of spatially resolved EL images of the cells during constant forward current operation at low (24 °C) and at elevated (70 °C) temperatures are recorded. The degradation induced changes in the open circuit voltage correlate well with changes in the EL intensities. The similarity of light‐induced and carrier‐induced degradation processes for mc‐Si cells is confirmed. The correlation of the degradation with the material structure is analyzed. The degradation appears to correlate with the density of structural defects in the cells. The results verify that EL images present a powerful tool for in situ analyses of mc‐Si cell degradation processes in various cell structures with a broad variety of biasing and temperature conditions.