This chapter presents a critical review of life cycle assessment (LCA) studies of solar photovoltaic (PV) technologies considering their technological and ecological developments, including silicon (Si)-based cells and modules (mono- and multicrystalline), thin-film cells and modules such as chalcogenides (CIS, CIGS, and CZTS), amorphous-Si (a-Si), cadmium telluride (CdTe), dye-sensitized solar cells (DSSCs), organic photovoltaics (OPV), and organic–inorganic halide perovskite (perovskite); PV systems (grid-connected, stand-alone, mounting methods, balance of system); and end-of-life (EoL) scenarios (such as landfill, incineration, and recycling). The reviews show that several studies are not using PV guideline assumptions, which results in a untrustworthy database. Assumptions of parameter values for LCA studies can have profound effects on results, and current assumptions are unrealistic relative to demonstrated results for several of the reviewed studies. Thus, while thin films appear to have better environmental outcomes (regarding global warming potential and energy payback time), this conclusion is not definitive given the current consistency of data. Quantitatively, the normalized global warming potential for thin-film technologies is 22–40 gCO2eq/kWh, followed by OPV 30–150 gCO2eq/kWh, followed by both crystalline silicon (c-Si) in the range of 40–200 gCO2eq/kWh and perovskite 150–1000 gCO2eq/kWh. However, LCA for c-Si technologies are currently more reliable than other technologies, given the latter's lack of consistency and assumption reliability. This review also identifies important challenges the field currently faces: (i) There is a shortage of data associated with end-of-life management of PV systems. (ii) The balance of system has been found to have significant impact and is often neglected in LCA studies. (iii) Likewise, transportation has significant environmental impacts, but data for this input is currently scarce. The same can be said for data on monitoring and reporting of a system's conditions. (iv) There is also a lack of economic analysis on material recovery from solar modules.