In this study, a simulation model of in-grid solar-to-electrical energy conversion system is presented. In this case, the in-grid solar-to-electrical energy conversion system is small photovoltaic power plant, which was constructed by the Center for Renewable Energy and Power Quality from Faculty of Technical Sciences (FTS). Equivalent circuit diagram of photovoltaic cell is described which was used to develop the simulation model of modules. Possible types and topologies of inverters are also described. The photovoltaic power plant is described briefly, because it is necessary to understand the simulation model. The result of simulation is an electricity annual production by the power plant. These results were compared with the real values, while its get a good overlap. The paper also presents the modern modeling methods developed at Faculty of Technical Sciences in the Laboratory for RES systems.