Solar energy is the most important type of modern and renewable energies. If it displace fossil fuels, can bring an end to concerns about finiteness of fuels, environmental pollution caused by the fossil fuels, price fluctuations and energy crisis. Among the energy sources, due to the high potential of solar energies in wide areas of the Iran, it has a great importance to researchers. The base of Photovoltaic technology is to converting sunlight into electricity and nowadays, most of the countries utilize it in the forms of grid-connected and off-grid. In recent years, few technologies are used for manufacturing of solar cells. The results  of investigating show that the efficiency of the first generation in comparison to the other technologies are high due to the high quality raw materials which are used in the fabrication. It is expected that the differences between the efficiency of these for technologies will be decreased by the time and other technologies will be replaced by the first generation. In this paper, the structure of different technologies has been studied and the possible methods for improvement of the solar cells efficiency have been introduced.