It is generally believed that there is no possibility of deterioration in the performance of silicon solar cells, occurring on the surface of the earth. However the electrical lightning which is quite relevant in a terrestrial power system may affect the cell performance significantly. For this, the effect of electrical discharge on the cell's series resistance, curve power factor, conversion efficiency and spectral response have thoroughly been investigated. The cells are found to exhibit large and permanent degradation in their characteristics. Some of the phenomena which might be responsible for this observed degradation are pointed out and discussed.