The application of PV systems in Iran has started since 1982, when a 1710 Watt power generator was installed in Fars (south east of Iran) to supply a telecommunication site by AEG. Till 1993 more than one hundred PV systems with various capacity and purpose of use have been installed over the country. In 1993 a production line for multicrystalline silicon solar cells and modules was installed in Tehran by the ministry of Post, Telegraph and Telephone (PTT). Since then the application of photovoltaic energy is spreading in various fields in Iran. In this paper the present and future state of photovoltaic plants, solar cell fabrication technology and optimization in system design and power conditioning are reported.