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Proceedings Paper

Design, manufacturing and measurement of a PV miniconcentrator for front point-contact silicon solar cells
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Paper Abstract

A novel photovoltaic concentrator has been developed in the framework of the European project "High efficiency silicon solar cells concentrator". In this project, front-contacted silicon solar cell have also been designed and manufactured by the project leader (the French LETI). This silicon cell concept is potentially capable to perform well (24% efficiency has been predicted) for much higher concentration levels than the back-contacted cells (and, of course, than the two-side contacted cells). The concentrator is formed by one lens of squared contour with flat entry surface and large-facet Fresnel exit surface, and a secondary that encapsulates the solar cell. On the contrary to the conventional Fresnel lens plus nonimaging secondary concentrators, the primary and secondary are designed simultaneously, leading to better concentration-acceptance angle product without compromise with the compactness. The grid lines in the front-contacted cells are aluminium prisms (which contact the p+ and n+ emitters, alternatively), acting as a linear cone concentrator that concentrates Cg =1.52× in the cross sectional dimension of the prisms. The secondary concentrator has a refractive rotational symmetric top surface that is crossed with two linear flow-line TIR mirror. Then, in the cross section normal to the aluminium prisms, the secondary provides a 2D concentration of Cg =12×, while in the cross section parallel to the prisms it provides a 2D concentration of Cg =24.16× as the grid lines in this dimension. Therefore, the cell is rectangular (1:2.08 aspect ratio), being the grid lines parallel to the shorter rectangle side. The total 3D geometrical concentration is 24.16×(12×1.52) = 455× for the square aperture and rectangular cell, and gets a design acceptance angle α=±1.8 degrees. Injection moulded prototypes are have been manufactured and measured, proving an optical efficiency of 79%. Computer modelling of the concentrator performance will also be presented.

Paper Details

Date Published: 3 September 2005
PDF: 11 pages
Proc. SPIE 5942, Nonimaging Optics and Efficient Illumination Systems II, 59420R (3 September 2005); doi: 10.1117/12.626140
Show Author Affiliations
D. Pérez, Univ. Politecnica de Madrid (Spain)
J. C. Miñano, Univ. Politecnica de Madrid (Spain)
P. Benítez, Univ. Politecnica de Madrid (Spain)
F. Muñoz, Univ. Politecnica de Madrid (Spain)
R. Mohedano, Univ. Politecnica de Madrid (Spain)

Published in SPIE Proceedings Vol. 5942:
Nonimaging Optics and Efficient Illumination Systems II
Roland Winston; R. John Koshel, Editor(s)

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