This paper is intended to present the results of our experimental study of defect in silicon solar cells. Solar cells defects are diagnosed by LBIC characterization and noise spectroscopy. Low frequency noise is a more sensitive tool for analyzing of degradation phenomena, like electro migration and sort of breakdown. All type of noise — thermal, shot, generation, recombination and 1/f type of noise play a different role in reliability analysis. The correlation between noise and transport characteristic indicates possibility of this diagnostic tool. Therefore the noise spectroscopy and LBIC is a pair of the very useful methods to provide a non‐destructive characterization on silicon semiconductor solar cells.