In this article we introduce distributed generation systems and identification of common units in the world. Also their applications, advantages and disadvantages would be presented. Fuel cell power plants that were installed in different capacities in all over the world are concidered. In this part a comperation among countries, time of installation, type of fuel cell, fuel prossessor and producer componies are presented in some figures. Then we will introduce 25 kw fuel cell grid conected system installed in Taleghan renewable energy site of SUNA. Also we present the technical spesifications, installation and operation proccess. 1)