Open-loop azimuth-elevation sun-tracking system using on-axis general sun-tracking formula for achieving tracking accuracy of below 1 mrad

A novel on-axis general sun-tracking formula has been derived and integrated into an open-loop azimuth-elevation sun-tracking system for improving the tracking accuracy. The installation defect of a 25m² solar concentrator prototype has induced significant sun-tracking errors, range from 12.12 to 17.54 mrad. With the use of CCD camera for recording the solar image, three misaligned angles from ideal azimuth-elevation axes have been determined and corrected by changing of the general formula parameters´ values to better the tracking accuracy to 2.99 mrad, which reach the encoder resolution limit of 4.13 mrad. Further fine-tuning has been made to attain the tracking accuracy up to 0.96 mrad, by including the motor step count, 1.64 × 10^-4°/step, which is beyond the encoder resolution. The general formula has been demonstrated to be capable of achieving reasonably high tracking accuracy cost effectively without complicated sun-tracking solutions.