Characterization of Core-Shell Spherical Lens for Microtracking Concentrator Photovoltaic System

Abstract

The optical characteristics of a radially symmetrical core-shell spherical (CSSP) lens is analyzed for its suitability to application in microtracking concentrator photovoltaic systems (MTCPVs). The CSSP lens is compared to a conventional homogenous spherical lens through both ray-tracing simulations and outdoor experiments. Simulation results show that the CSSP lens is superior to the conventional homogenous spherical lens in terms of its optical efficiency for long focal lengths, for which the CSSP lens exhibits less spherical and chromatic aberrations. Outdoor experiments are conducted using test concentrator photovoltaic (CPV) modules with prototype CSSP and homogenous spherical lenses; the trend of the measured short circuit current agrees with the that of the simulated optical efficiency for both lenses. Furthermore, compared to the homogenous lens, the CSSP lens significantly increases module efficiency because of its better illumination uniformity at the solar cell surface. The optical characteristics of the CSSP lens are preferable for MTCPVs with a spherical lens array to achieve a higher module efficiency for a wider incidence angle although further studies on more practical system configurations are needed.

Optimization of the Secondary Optical Element of a Hybrid Concentrator Photovoltaic Module Considering the Effective Absorption Wavelength Range

“…The origin of the technique to obtain solar energy effectively using a concentrator is considered to be a combination of reflector and thermal collector, since the late 1970s [1,2]. The technique has been further advanced, and concentrator photovoltaic (CPV) modules have been actively studied to reduce costs and improve performance [3][4][5][6][7][8][9][10][11][12]. CPV modules are highly efficient power generators in high-direct normal irradiance (DNI) regions near the equator, but less effective in the global normal irradiance (GNI) mid-latitude regions, where these modules do not perform as well as flat photovoltaic (PV) modules.…”

“…In addition, hybrid CPV modules can maximize power generation in the high-DNI regions without requiring as much volume, since they absorb scattered light more efficiently [11]. Lee et al experimentally analyzed two types of hybrid CPV modules with concentration ratios of 18X and 1000X and showed high power generation efficiency [12]. Yamada et al combined the two-terminal triple-junction (TJ) solar cell and bifacial crystalline silicon solar cell for their hybrid CPV modules, and performed analyses based on the (GNI-DNI)/GNI ratio [13].…”