Optical Performance of a Heliostat in the DAHAN Solar Power Plant

This study analyzes the characteristics of the heliostat beams in response to various heliostat adjustment methods and the changes of the beam characteristics with time. The measurements are compared with theoretical values predicted by a model of a 1 MW solar power plant's solar flux distribution based on Monte Carlo ray tracing. The appropriateness of the centroid method and the geometric centre method to determine the heliostat beam geometry and centre are evaluated based on comparisons with heliostat beam grey images taken in the DAHAN solar power plant. The results show that alignment of the heliostat by these two alignment method are both acceptable even though the predictions have some differences with the measurements. The geometric centre method more accurately calculates the spot centre because this method eliminates the effect of saturation on the beam characteristics and more exactly analyzes the total energy reflected into the receiver.