Multi-junction solar cell technology, based on III-V semiconductor structures grown onto Germanium substrates, is well established as the primary photovoltaic technology used in satellite power generation. As future satellite power requirements will significantly increase due to the adoption of technologies such as electrical propulsion, sensing and telecommunications, next generation space solar cells will be required to significantly increase their conversion efficiency to enable higher energy generation with minimal increase in overall system weight and cost. To this end, this proposal will develop multi-junction space solar cells on high quality, low cost, large area (150mm diameter) Germanium substrates, which will have conversion efficiencies >33% (AM0), utilising novel 4-Junction architectures. The process will adopt dilute nitride epitaxial technology that has been developed by Nanyang Technological University (1). To enable this, a powerful consortium has been assembled, which covers the entire skill set required to produce such cells, including substrate manufacture, advanced epitaxy, device design, device fabrication, test and qualification. (1). Molecular beam epitaxy grown GaNAsSb 1 eV photovoltaic cell, K.H. Tan, S. Wicaksono, W.K. Loke, D. Li, S.F. Yoon, E.A. Fitzgerald, S.A. Ringel, J.S. Harris Jr, Journal of Crystal Growth 335, pp66-69, 2011.