Enhanced irradiance distribution on solar cell using optimized variable-focus-parabolic concentrator

A solar cell concentrator system is proposed comprising a square solar cell and a variable-focus-parabolic (VFP) reflector in which the focal length varies as a function of the horizontal displacement of the incidence point relative to the vertical centerline of the solar cell. The light ray paths within the concentrator system are analyzed using an exact analytical model and a skew-ray tracing approach. The geometry of the VFP reflector is then optimized in such a way as to maximize the uniformity of the irradiance distribution on the solar cell given a circular focus spot and a square focus spot, respectively. The effectiveness of the optimized VFP reflector with a square focus spot is investigated by means of ZEMAX simulations. It is shown that the optimized VFP concentrator yields a significant improvement in the irradiance uniformity compared to that achieved using a conventional parabolic concentrator.