Influence of Solar Tracking Inaccuracy and Sun Rays Modeling on the Efficiency of a Small-scale Parabolic Trough

Abstract

Tracking systems for parabolic troughs are already well designed for industrial processes, but the challenges can be different concerning small-scale low cost systems. Considering cost limitations, some flexibility and error margin on tracking accuracy may be tolerated, due to the imperfections of the parabola or the inaccuracy of the tracking. The objective of this study is to compute the efficiency losses when changing the sun rays incident angles and conclude about the error margin tolerable for a small-scale parabolic trough. Starting from an ideal case, the evolution of the trough efficiency regarding the tracking angle is observed in the plane perpendicular to the axis of a polar mounted trough. A ray tracer is used to simulate the illumination of the absorber. A simplified model for representing the angles of rays from the sun is suggested to take account of all the rays not being parallel.