Direct Tracking Error Estimation on a 1-Axis Solar Tracker
Abstract
The characterization of the precision of a solar tracker used in solar thermal collectors is not currently standardized. Nowadays, existing testing standards consider a solar tracker as part of the solar collector and do not take into account the tracking precision, without any kind of tracking characterization or checking. This paper is focused on the estimation of tracking errors using a direct procedure to estimate the maximum tracking angular deviations of a solar tracker. First, a testing procedure of a solar tracker has been defined. Secondly, the real tracking error of a low-cost 2-axis solar tracker has been measured with a simple method using a digital inclinometer. The direct characterization of the elevation of a solar tracker in one axis has been compared to the solar elevation, in order to estimate the angular deviation of the tracker in one angle. Finally, the statistical distribution of the tracking error has been calculated and compared to the acceptance angle of medium temperature concentrators to check if its precision is enough for its optics. The measurement repeatability was checked of ± 0.05°. The maximum instantaneous error of elevation for this tracker was more than 3º but in general was within ±2º. The accuracy of the tracking considering no positioning error was within ±0.6º. The acceptance angle of different solar concentrators has been compared to the solar tracking accuracy. It has been conclude that the medium temperature collectors studied were adequate with this solar tracker.
Keywords
One-axis tracking, Elevation characterization, Testing procedure