Approach to advanced clearness index modelling

Modeling of photo-voltaic (PV) system electrical energy production is necessary in order to determine the most efficient parameters (slope, azimuth, etc.) at the location of planed PV system. The most common methods in PV plant modelling use multi-year average input values of irradiation and temperature for a selected location. When using multi-year averages it is necessary to take into consideration possibilities of single year variations. Each year can deviate more or less from the average values, which can be assessed by comparing the last few years with the average year, possible only if the measured data for the specified location is available. In this research a single year of measured data is used to find a better description of the location for the existing PV systems. The results will later enable better modelling of any PV system in the area near the provided PV and measuring systems. Clearness index is a ratio of the solar irradiation on the horizontal surface on Earth and irradiation at the top of the atmosphere.