On the example of the grid-connected photovoltaic power plant located in Vrgorac, an analysis of electricity production during a five-year period was made. Using the software program "Photovoltaic Geographical Information System" (PVGIS), a simulation of the power plant operation was performed for the purpose of estimating electricity production. Using the data on the measured electricity production, the analysis of the operation of the photovoltaic power plant on a monthly and annual basis was performed. The introductory part presents and describes photovoltaic systems, connection methods and the elements of which they consist. Several examples of network photovoltaic power plants that have been built, that is, that are planned to be built in the Republic of Croatia, are presented. Based on the conditions for the purchase of electricity and measured data on electricity production, an economic analysis of the operation of the photovoltaic power plant was performed and the cost-effectiveness of the system was assessed.