Advanced surface reconstruction method for solar reflective concentrators by flux mapping

Accurate determination of curvature and surface distortions on solar reflective concentrators is crucial, since flux distribution on the receiver depends on it. Here, a new optical characterization technique able to determine the shape of a solar concentrator from a single flux map measurement is presented. With this technique, the shape of a model heliostat is iteratively varied until the Pearson correlation coefficient between the simulated and the measured flux maps is maximised. The use of a single flux map is made possible through discretisation of the heliostat and target surfaces into two-dimension meshes and a careful choice of heliostat-target distance in the experiment, that must be much shorter than the heliostat focal length. Employing a mesh density of 1 normal vector per 4 cm2, yields correlations higher than 0.99999 with a root mean square slope deviation uncertainty around 0.25 mrad for heliostats of 1.6 m x 1.9 m.

Automated summary

A new optical characterization technique for determining the shape of solar concentrators is presented, based on analyzing the correlation coefficient between measured and simulated flux maps. By discretizing the concentrator surfaces and adjusting their shapes iteratively, the technique allows characterization using a single flux map.