New concentrator multifocal Fresnel lens for improved uniformity: design and characterization

Autor: Angel García-Botella, Daniel Vázquez-Moliní, Alfonso Domingo-Marique, Eusebio Bernabeu, Antonio Álvarez Fernández-Balbuena, Javier Muñoz de Luna Clemente
Rok vydání: 2009
Předmět:
Zdroj: SPIE Proceedings.
ISSN: 0277-786X
Popis: The emergence of high efficiency photovoltaic cells is leading the industry into using solar concentrators in order to reduce costs by decreasing the number of cells used. In this paper Optics department of Universidad Complutense de Madrid has designed a multifocal Fresnel lens of PMMA and has studied the main parameters that have influence on its final function. This has been done by taking into account its manufacturing tolerances. The lens is square shaped with sides measuring 270 mm and it is composed of three different zones based on three different criteria: The central zone has been designed by using paraxial formulation, the intermediate one has been designed based on Fresnel classical formula while the marginal zone's purpose is to deflect the light by total internal reflection on prism faces. All three zones have different focal areas and different optical axis so the energy distribution will be more uniform whilst avoiding cell damage caused by hot spots. The design stage is feedback through simulations using a ray tracer software. In order to characterize the lens operation a measure of optical concentration was first taken on different lens areas using an integrating sphere. Finally, the lens performance in terms of concentration and in terms of uniformity at the focal spot was studied by processing the images taken with a CCD camera on a screen placed at the focal plane of the lens.
Databáze: OpenAIRE