Light induced degradation of single junction and double junction a-Si:H solar cells has been studied. Cells with and without buffer layers at the p/i interfaces have been fabricated. It is found that light induced degradation is faster in the cells with buffer layers. Defect density increases faster and degraded efficiency with respect to the initial efficiency decreases at a higher rate for the cells with buffer layers. Spectral response study for double junction cells shows that collection efficiency decreases for the bottom cell only. So it is found that the absolute stabilized efficiency is highest for a double junction cell with buffer layer at the top cell only.