Modeling of solar tracking for giant Fresnel lens solar stoves

A fundamental modeling for the optical features and control algorithm has been developed for a solar stove heat collection system which uses a giant Fresnel lens. The modeling work helps to implement autonomous solar tracking in the system by controlling the Fresnel lens to maintain a stationary focal point on the heat-collecting surface of the solar stove. Two-axis solar tracking for the particular work was chosen. The update time interval during tracking causes misalignment of the lens' optical axis versus the sunrays. From modeling, the defocus (due to the misalignment) and the change of the shape and location of the focal point on the static heat-collecting surface could be calculated. The results of the analysis have been incorporated into the control algorithm which has been implemented in the control system of a prototype solar stove which successfully demonstrated the predicted efficient solar tracking.