The course is an introduction to the photovoltaic (PV) applications in the general mix energetic context dominated by climate warming mitigation. The various uses of solar energy are firstly presented before a short description of the principle of the direct solar photon conversion into electricity (PV). The various PV technologies are reviewed in the current context dominated by crystalline silicon cells. The perspectives of the various technologies are then analysed in terms of R&D investments. From a more scientific point of view the basis of the solar cell operation is presented from the solar spectrum characteristics. The fundamentals of PV conversion are summarized. In particular the various sources of the conversion efficiency limitations are reviewed. The solar PV systems, from cells to grids, are also addressed, with a particular emphasis on the challenges of grid-integration of PV and the development of storage technologies. The environmental and social impacts of PV are compared to the competing energy sources. Generally PV is at advantage as referred to other fossil or renewable sources. Finally the fast evolution of economics and financing of PV is presented together with the current key players, mostly Asian companies.