Sistema de rastreamento solar automático baseado em algoritmo de posição solar aplicado a um refletor fresnel linear

Abstract

The use of solar energy can be a significant alternative to meet the growing demand for energy. In this context, solar concentrators have emerged as a very promising option. This research presents a model of automation of a solar tracker that dispenses the use of sensors to determine the position of the Sun. This determination is made only based on astronomical aspects, using an algorithm for calculating ephemeris, through which it is possible to predict the solar position by determining the values of the azimuth angles and solar elevation through time counting data constantly updated by a clock applied to the equation programmed in an Arduino module. For this, a comparison was made between two equation methods of apparent solar position, one of them based on Duffie and Beckman (2013) and the other based on Reda and Andreas (2008), the latter has the advantage of having a known uncertainty of 0.0003°, and the disadvantage of requiring a much more complex equation compared to the first method. Through simulations to obtain the required accuracy value that the tracking method should have to remain within the limits of the absorver area. It was verified that only the second method could provide the values within the required range of 0.2°. To confirm the applicability of the calculated values in the programming, it was simulate in the Tonatiuh software, in addition to measurements made directly on the mirrors, through a slope sensor with a resolution of 0.2°. The results obtained in the calculations were satisfactory, since they presented values very close to the simulated ones (maximum difference of 0,1º between both), whereas for the measured ones, the maximum difference for the calculated value was of 0.14º. After this confirmation, the values obtained in the programming have been applied in the positioning of a step motor responsible for the activation of a set of 14 mirrors coupled to each other and designed to concentrate the radiation in an absorber, using the technology of Fresnel Linear Reflector. This movement uses only one trigger, based on the observation that the values of the angular difference between the mirrors remain constant throughout the day.