Target-Aligned Heliostat Field Layout for Non-Flat Terrain

Abstract

The layout for a solar tower test facility for CSIR, Pretoria, is described. The solar tower system is designed for 400kWth receiver outlet power. The heliostat field layout takes into account both the real (non-flat) topography of the terrain as well as the typical weather conditions at the site, with usually better solar conditions in morning times. As first step, an initial field layout was done assuming standard heliostats. Then, the performance improvement due to the use of target-aligned heliostats was evaluated, showing nearly 12% gain in annual energy when optimized canting angles are applied to each heliostat. In a second step the positions of the heliostats were adjusted to further improve the annual energy yield. This was done by slightly shifting the position of a heliostat and evaluating the impact on annual energy yield. No restrictions were made on the heliostat positions, except for a minimum distance between neighbouring heliostats. The heliostats were repositioned one after the other for the whole field. This procedure was repeated many times. At the end of this optimization, the annual intercepted energy was about 5.1% higher than the initial configuration with target-aligned heliostats.