In this paper, we introduce a concept for the utilization of Data over Power Line (DoP) for space applications to extend the currently available networking between components and subsystems and to benefit from the resulting harness reduction. DoP makes use of the already existing power lines in a spacecraft (S/C), since each of the electronics needs to be powered. The proposed system uses a commercially available DoP modem to convert between digital signals and a modulated carrier that is superimposed onto the DC power lines. The utilization of this technique also needs to pass significant challenges whereas solutions are presented in this paper. For this reason, we introduce possible network topologies which can be used in spacecraft systems. Furthermore, we give an insight into the development of the end-to-end communication demonstrator and illustrate the use cases for our latest spacecraft projects, i.e. CompactSat or S2TEP satellite platforms. We also explain the modes of operation, and we will present the results of the electromagnetic compatibility (EMC) tests, which is one of the most challenging concerns, when using DoP in a spacecraft. Finally, we conclude the harness reduction potential that we expect for a reference DLR spacecraft mission.