Flexible monolithically series-integrated a-Si thin film modules on polyimide substrate were fabricated.The advantages and important fact ors of roll -to-roll fabrication method for flexible monolithically series-integrated a- Si thin film modules on polyimide substrate were analyzed.Two structures of monolithic modules were designed.At last,the flexible monolithically series-int egrated a-Si thin film modules on polyimide substrate were fabricated based on roll-to-roll technolog y,were compared.The monolithically series-integrated sing le-junction modules have solar energy conversion efficiencies of 5.96% a t AM1.5spectrum with total-area of 117.3cm².