EXPRESSION FOR ESTIMATING THE ANNUAL VOLUME OF ENERGY PRODUCED BY A PHOTOELECTRIC ARRAY

Abstract

This paper proposes an analytical expression in the form of a second-degree polynomial for calculating the annual volume of energy produced by a photovoltaic array depending on the modules tilt and their installed capacity. The resulted expression is based on NASA long-term average solar radiation intensity database and can be used to estimate the energy parameters of photovoltaic systems when their operating in the climatic conditions of the Kherson region. It was found that the dependence of the annual energy production on inclination angle of south-oriented photovoltaic array has the form of a curve with a maximum at the module’s inclination angle of about 30°, that is why the search for equations capable to describe this dependence was carried out in the form of polynomials of the second, third and fourth degrees. Comparison of the calculation results by the polynomials with the expected photovoltaic array annual generation at module tilt in the range from 0 to 90° showed that the second-degree polynomial function allows describing the dependence with an accuracy of no worse than 99 % in the entire range of angles studied, while the use of third- and fourth-degree polynomials leads to an unconformity of more than 1 % at module tilts greater than 50°. The practical application of the obtained analytical expression in the form of a second-degree polynomial makes it possible to significantly simplify and speed up the procedure for determining the expected annual volume of energy produced by a photovoltaic array in the climatic conditions of the Kherson region, having at the disposal only the inclination angle of the south-oriented modules and the nominal power of installed array.