The Effect of Solar Radiation Data Types on Calculation of Tilted and Suntracking Solar Radiation

Energy yield assessment of photovoltaic systems is inherently non-linear. The calculation chain starts with simulation of solar radiation, where many factors are considered: sun’s position, terrain, properties of the atmosphere and cloudiness to determine the absolute value of global irradiance and the ratio of diffuse and direct components. The ratio of direct and diffuse components influences the global irradiance received by the inclined surface of PV modules, it changes during a day and also during seasons and it is highly dependent on the geographical location. Therefore, optimally multiyear time series should be used for proper modeling of energy performance of a PV generator. However, for historical reasons, several solar radiation data products with different level of simplification are used in PV simulation tools – long-term monthly-averaged daily profiles, synthetic time series, and typical meteorological years (TMYs). A new simplified approach is based on the statistical aggregation of solar radiation into relevant groups (bins) according to distribution of irradiance values. This paper seeks to provide a benchmark for four solar radiation data products used in the contemporary software packages for performance assessment of photovoltaic systems. The results of calculation the in-plane irradiation show different performance of data products, when compared to full time series, with error amplitude up to ±3%.