Purpose. Improving the efficiency of photovoltaic power plants in power systems by creating a model for forecasting the amount of electricity produced in the form of a harmonic function and determining the prospects for using the selected mathematical software to develop software applications. Methodology. To determine the amount of electricity generated by photovoltaic plants per day and year, statistical methods are applied using the harmonic function which allows taking into account the main meteorological factors of power change of photomodules. A technique is proposed for taking into account the level of generation by photovoltaic stations to track changes in voltage levels in the connection nodes. Findings. Mathematical models for forecasting the electricity generation of photovoltaic stations for different time ranges are built. The influence of weather factors, the length of daylight and the structure of the local generation system on the level of electricity generated by photovoltaic plants is investigated. Necessity is conditioned to use a harmonic function for forecasting the amount of electricity produced, which improves the efficiency of calculations for new and existing power plants. Originality. The factors of the influence of daylight hours and cloudiness on the level of electricity generation by photovoltaic stations are taken into account, as well as meteorological data that make it possible to predict the value of the amount of electricity generated for a certain period of time. The dependences of the amount of generated electricity by photovoltaic stations are obtained in the form of a harmonious function with reference to a coefficient that takes into account the cloud level for predicting generation volumes. Practical value. Created mathematical models of forecasting by means of harmonic function and analysis of voltage change in nodes of local networks allow increasing the efficiency of photovoltaic stations, simplify calculation of change of levels of voltages in a electric network, the forecasted values of the generated electric power on the day ahead system on the basis of duration of the light day, meteorological data and other external factors at commissioning of photovoltaic stations.
