Initial Validation of an Advanced Heliostat Characterize ion System Based on Cameras and Light Detectors

The design of the commercial Solar Power Tower Plants erected during the last years has been strongly influenced by the need of increasing the output power of the receiver to reach cost-effective plants. This trend has led to large heliostat fields with a vast number of long-distance heliostats that cannot be accurately characterized by the stateof-the-art methodology. Besides, the trend in heliostat design during the last decade has been the reduction of the heliostat size. This reduces, in the same way, the flux density produced by each heliostat individually, which makes it even harder to characterize the heliostat in a precise way. In order to surpass the state-of-the-art capabilities, a novel technique and an advanced measuring system was developed to characterize heliostat reflected beams. This system can accurately measure the power density distribution of any heliostat independently of its size or distance by its direct measurement using an array of opto-electronic detectors with a novel scanner-based procedure, in which the reflected beam drifts over the system due to the Sun movement while the heliostat remains immobile. In this context, this article presents the development status of the prototype built to demonstrate all the capacities that this innovative technique has. In addition, the results obtained during the initial tests performed as a proof of concept of the technique are presented, which shows really promising results in terms of measurement quality and potential to succeed in reaching high-quality characterization for both distant and small heliostats. Moreover, the development of a novel capability for the presented technique is presented, which provides the ability to characterize the heliostat surface slope by using a set of cameras attached to the characterization system and taking advantage of its scanning procedure.