New Fresnel Köhler optical design: 9-fold photovoltaic concentrator

Abstract

Non-uniform irradiance patterns created by Concentrated Photovoltaics (CPV) concentrators over Multi-Junction Cells (MJC) can originate significant power losses, especially when there are different spectral irradiance distributions over the different MJC junctions. This fact has an increased importance considering the recent advances in 4 and 5 junction cells. This work presents a new CPV optical design, the 9-fold Fresnel Kohler concentrator, prepared to overcome these effects at high concentrations while maintaining a large acceptance angle, paving the way for a future generation of high efficiency CPV systems of 4 and 5 junction cells.

Annihilation upconversion: harvesting the entire deep-red spectral range of the sun irradiation

“…This extremely broad excitation spectrum solves another technological problem, limiting the sunlight-based energy storage technologies: UC-devices application should require as low as possible sunlight concentration and allow application of nonimaging optical devices, such as solar concentrators based on Fresnel lenses 23 or 2-D polymer microlens arrays. Even a very low sunlight concentration ratio (<10 times) obtained by Fresnel-Köhler flat optical design 24 lenses, aspheric lenses created on a flat polymer substrate, 25 polymer microlens arrays obtained by ink-jet printing technique, 26 or microlens arrays based on polymer network liquid crystal 27,28 allows the effective transformation of the deep-red sunlight spectral range via the studied process of TTA-UC in visible light.…”