Numerical method and new analytical models for determining temporal changes of model-parameters to predict maximum power and efficiency of PV module operating outdoor under arbitrary conditions

Abstract

In this work, a novel approach has been presented to predict real-time maximum power, conversion efficiency, daily, monthly and yearly energy production of photovoltaic modules operating outdoor from dawning to evening under changing conditions of illumination and temperature. One-diode electronic circuit with five irradiance and temperature dependent model-parameters has been used to describe the photovoltaic module. Temporal monitoring of temperature and module photovoltaic metrics, during one reference day, has been used to solve the system of non-linear equations corresponding to key-points of current-voltage curve to determine real-time values of model-parameters. New analytical formulas have been proposed to reproduce variations of daytime values of model-parameters as functions of effective irradiance and module temperature for all days of the year. To evaluate accuracy of our predictive approach, meteorological and photovoltaic data recorded by NREL researchers for four PV modules coming from different technologies, which were operating outdoor at Cocoa (Florida) and Eugene (Oregon) during one year have been used. Predicted values of current-voltage characteristics, maximum power and efficiency at arbitrary times in arbitrary days have been compared to respective experimental values. NRMSE and NE have also been calculated to find that these normalized indicators have not exceeded 3%.