Solar central receiver or "power tower" thermal energy systems demand high precision heliostat tracking. Large numbers of heliostats in the field need to precisely track their own targets. Such a scenario suggests a hierarchical control architecture in which a model based controller could occupy the supervisory level. A novel two-level control architecture consisting of the NREL SPA (Solar Position Algorithm) and ANFIS (Artificial Neural and Fuzzy Inference System) as supervisory control is presented. The ANFIS system offers reduced complexity and allows for the quick simulation of various heliostat geometries without solving the kinematics. The initial system design, simulation and tracking results using Matlab SimMechanics and Simulink are given here.

Power tower" or central receivers are a type of solar thermal energy system in which many heliostats, or movable planar mirrors, are used to focus sunlight onto a central receiver located on top of a tower. To design a control and calibration system for power tower systems, a thorough understanding of the numerous errors which can be present is essential. In this work, the various and different types of errors that present themselves in heliostat based solar energy systems are identified, categorized and assessed based on their potential impact and level of difficulty of resolution. The results of this work can be used to aid in designing a control system for heliostats in which the greatest amount of error can be corrected with the least difficulty.