TCO films are crucial components of almost all thin-film solar cells and a-Si:H/c-Si heterojunction solar cells. As they are used as front contacts, the requirements for electrical conductivity and optical trnamission are generally very high. Further restrictions are imposed onto the deposition process by the cell manufacturing process, in which e.g. the maximum substrate temperature can be limited. In this paper the optimization of ZnO:Al layer deposited by magnetron sputtering to different solar cells is discussed. For a-Si:H/c-Si heterojunction solar cells the advantages and limitations of different variations of magnetron sputtering of ZnO:Al are discussed and compared to standard ITO deposition. For a-Si:H/μc-Si:H the usage of post-deposition treatments to improve the optical and electrical performance is briefly discussed. © 2013 SPIE.