This paper begins with an introduction to the concept of space solar power (SSP) and summarizes selected prior studies of proposed solar power satellite (SPS) systems. The functional components of a generic SPS are delineated, and various approaches and promising concepts from prior and current development efforts are elucidated. The fundamentals of wireless power transfer for the SPS application are reviewed, including a discussion of retrodirective beam control approaches. A survey of related technology research and development campaigns for energy conversion and transmission modules for recently proposed modular architectures is outlined. Advances in solid state amplifier technology with relevance to SSP are reviewed, with areas of particular criticality highlighted. Performance metrics for proposed SPS systems and their components are enumerated, and efforts to design, fabricate, and test a prototype conversion module operating at 2.45 GHz in a space-like environment are described.