Analysis of Drift Phenomena in Heliostat Images

Abstract

Heliostat image drift is defined as the wandering of the irradiance spot produced by a heliostat on a receiver or observation screen. Two factors producing heliostat image drift have been analyzed theoretically in the present paper: errors in reference position, and time delay. Some regular behavior is found in the drift curves. Maximum deviations from target tend to be linearly dependent with either angular error, or time delay. In particular, the curves produced by this later effect are circular or elliptical. Heliostats at different distances from a tower have been analyzed. For heliostats far from the tower the drift curves due to errors in reference position also have a more or less elliptical shape. Results are presented as dimensionless quantities. Some practical implications of these results are discussed.

Modeling of Drift Effects on Solar Tower Concentrated Flux Distributions

“…Drift is defined as the wandering of the concentrated light spot produced by a heliostat. The different types of drift and their causes have been discussed in detail [8,17]. This leads to a statistical distribution of tracking errors that has been shown to differ from the conventional Gaussian behavior [9].…”