Theoretical analysis of error transfer from the surface slope to the reflected ray and their application in the solar concentrated collector

Surface slope error of concentrator is one of the main factors that influence the performance of the solar concentrated collectors which cause deviation of the reflected ray and reduce the intercepted radiation. This paper presents the general equations to calculate the standard deviation of the reflected ray error from that of slope error through geometry optics analysis, applying the equations to calculate the standard deviation of the reflected ray errors in five kinds of solar concentrated reflector, and providing typical results. The results indicate that the reflected ray errors at one direction may come from the optic errors of both directions when the incidence angle is more than 0. The error transfer from the surface slope to a reflected ray is enlarged to more than twofolds in the heliostats, solar troughs, and linear Fresnel solar energy collecting system. The equation for the reflected ray errors is generally fit for all reflection surfaces without refraction, and can also be applied to control the errors in designing an abaxial optical system.

► Error transfer equation from the surface slope to the reflected ray is presented.
► The slope error is enlarged to the reflected ray on a reflector.
► The slope error from two directions is transferred to one direction of the reflected ray.
► The reflected ray error of solar concentrator is often more than 2 times of the slope error on a reflector.