We have developed monolithically integrated CIGS submodules with efficiencies of as high as 15.0 % on stainless steel substrates. The surface of the stainless steel substrate was coated with an anodized Al₂O₃ layer which makes the monolithic integration possible. The demonstration of high-efficiency flexible submodules on low-cost substrates can lead to a wide variety of applications such as car, space, and power applications, in addition to exsisting niche and mobile applications.