A simple method for predicting the output of dual-axis tracking systems from fixed-tilt system outputs

This paper begins by summarising a piece of work by the author which conducts a comparative analysis on the variability of fixed-tilt (FT) system and dual-axis tracking (DT) system. The results of this work revealed a relationship between the variability of the two systems associated with sun position. Consequently, a simple method for predicting the output of DT from FT output data was developed. The method is applied to the prediction of both magnitude and variability; the performance results of the method are presented and show it to be acceptable as an easily implemented prediction technique in the case where irradiance measurements at the sun´s elevation angle are not available.