Open AccessA fractal concentrator of direct and indirect sunlight
Author(s) -
Ilia Katardjiev
Publication year - 2020
Publication title -
clean energy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.593
H-Index - 8
eISSN - 2515-4230
pISSN - 2515-396X
DOI - 10.1093/ce/zkaa017
Subject(s) - optics , nonimaging optics , concentrator , transmittance , sunlight , geometrical optics , ray tracing (physics) , suns in alchemy , acceptance angle , refraction , fresnel lens , solar energy , radiation , physics , specular reflection , refractive index , x ray optics , physical optics , reflection (computer programming) , optoelectronics , lens (geology) , engineering , computer science , x ray , electrical engineering , programming language
A novel concept for concentrating both direct and indirect sunlight employing a combination of waveguiding and refractive optics is presented. More specifically, it is based on both the individual and the collective focusing effects of an array of refractive optical elements of specific geometry. An analytical framework and design principles regarding the geometry of the optical elements taking into account Fresnel reflection and refraction are presented. The principle of operation along with loss mechanisms and acceptance angles are discussed in detail. Ray-tracing simulations of a light concentrator designed accordingly indicate transmittance >90% with acceptance angles of ≤65° at 3 suns for moderate refractive indices. It is further numerically demonstrated that the new approach allows the utilization of the dominant fraction of the solar radiation by harvesting the waste heat in addition to photovoltaic conversion with an operating energy efficiency for diffuse light >70%.
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