Design of a linear Fresnel lens system for solar photovoltaic electrical power source

The object of the paper is to describe how a linear Fresnel lens is designed using I-DEAS(R) (Integrated design, engineering and analysis software) package. The design is carried out by drawing three curves from the focal point at specific radii. A vertical line is drawn at the extreme right end of the curve. By drawing a tangent and a normal at that point, the refracted angle is found out using Snell's law. The refracted ray is extended to meet the arc. Then suitable angles of incidence and refraction are found at that point such that Snell's law is satisfied. The new normal is drawn and the perpendicular to it forms a lens tooth. Equidistant points are plotted on the lens profile and by Lagrange's interpolation the groove angles at each point are determined. By drawing the lens tooth at the suitable groove angles, one half of the lens profile is created which is then mirrored and extruded to get the full profile. The significance of this work is that it ensures the precise focusing of the entire incident light along a straight line without any scatter. This reduces the effective photovoltaic cell area needed and hence cuts the cell cost tremendously. The thickness of the lens is 4mm, which enables it to be bent and mounted easily.