Optical Design of Spherical Silicon Solar Cells with Reflector Cup

Abstract

A short-circuit current density (Jsc) of a spherical Si solar cell with a reflector cup has been calculated as a function of light concentration ratio, defined as the aperture area of the reflector cup divided by the projection area of the spherical Si solar cell, and incidence angle using a three-dimensional ray-tracing simulation. The calculation results show that the Jsc values of 39.7, 38.4, and 38.1 mA/cm2 can be obtained with the light concentration ratios of 4, 6, and 8, respectively, indicating that a higher concentration ratio reduces the optical efficiency of the reflector. Also, these results indicate that Jsc approaching 40 mA/cm2 can be realized without surface texturing in the spherical Si solar cell. Even in a high light concentration ratio of 8, a relatively high Jsc exceeding 37 mA/cm2 can be obtained for the incidence angles of 0–10°, indicating that the amount of spherical Si can be reduced effectively by the reflector cup.

Effects of heat treatment on fluorine-doped tin oxide anti-reflection films coated on silicon spheres

“…Anticipated advantages of spherical Si solar cells include flexibility and scalability. To date, the performance of spherical Si solar cells has been improved by production of high-quality Si spheres, 2),4)13) formation of textured surface structure, 14) deactivation of defects by passivation, 15) optimization of the concentrator module and reflector cup, 16), 17) and coating with anti-reflection (AR) films.…”

Microstructures and Optical Properties of Silicon Spheres for Solar Cells

“…3,4,[6][7][8][9][10][11][12] Flexible and light weight spherical Si solar cells are also anticipated, and will be valuable in situations such as responding to emergency disasters. The conversion ef ciencies of spherical Si solar cells can be increased by producing high-quality Si spheres, 3,4,[6][7][8][9][10][11][12][13][14][15] forming textured Si surface structures, 16) deactivating defects by passivation, 17) optimizing the concentrator module and re ector cup 18,19) and preparing anti-re ection (AR) lms on the spherical Si solar cells. 12,[20][21][22] Si spheres have typically been grown by a dropping method.…”

Synthesis of Silicon Microspheres

“…Recently, the photovoltaic industry has seen a rapid development due to increasing efforts in environment preservation. In particular, spherical silicon solar cells, based on small-size crystalline silicon microspheres have attracted considerable interest for saving the silicon feedstock and realizing low-cost photovoltaic modules [13][14][15][16]. Silicon microspheres can also be used for detectors, modulators, and optical switching because silicon-based Raman lasers can overcome those shortcomings such as large nonlinear optical losses and low output efficiency existing in conventional Raman lasers [17][18][19][20].…”