Assessment of the pointing error of heliostats with a single not polar rotation axis for urban applications

In this paper, the behavior of this kind of heliostat as a generic one, whose axis does not need to be oriented along the direction of the polar axis, has been studied. It has been found out that it is possible to define a direction around the heliostat must rotate in order to reflect sunbeams toward the desired point with high precision. Additionally, the pointing errors of the device proposed have been analyzed. Considering that the lengths traveled by reflected sunbeams in urban applications are of about tens of meters, the errors estimated (0.01 rad average pointing error) are assumable since they would entail absolute errors of the order of centimeters.