New nonimaging static concentrators for bifacial photovoltaic solar cells

Two new static nonimaging designs for bifacial solar cells are presented. These concentrators have been obtained with the Simultaneous Multiple Surface design method of Nonimaging Optics. The main characteristics of these concentrators are: (1) high compactness, (2) linear symmetry (in order to be made by low cost extrusion), (3) performance close to the thermodynamic limit, and (4) a non-shading sizable gap between at least one of the cell edges and the optically active surfaces. This last feature is interesting because this gap can be used to allocate the interconnections between cells, with no additional optical losses. As an example of the results, one design for an acceptance angle of +/-30 degrees gets a geometrical concentration of 5.5x, with an average thickness to entry aperture width ratio of 0.24. The three dimensional ray-tracing analysis of the concentrators is also presented.