Nonuniformity Sunlight-Irradiation Effect on Photovoltaic Performance of Concentrating Photovoltaic Using Microsolar Cells Without Secondary Optics

Abstract

We propose a compact 20-mm-thick concentrating photovoltaic (CPV) module that is much thinner than conventional CPV modules. To achieve this structure, we assembled a CPV module by placing microsolar cells with an area smaller than 1 mm2 directly on the back of a lens array. Since our CPV module has no secondary optics, the incident sunlight is focused through the lens array onto the solar cell so that the light intensity is nonuniformly distributed due to chromatic and comatic aberration. In this paper, we analyze the dependence of the short current ( $I_{{\rm sc}}$ ) and the fill factor of our CPV module on the area, the position, and the intensity distribution of the irradiated sunlight on the solar cell. Our results indicate that the main factor that affects the PV performance of our CPV module is not the sunlight's nonuniform irradiation in the three-junction subcells due to chromatic and comatic aberration but the resistance loss between the emitter layer of the top cell and the grid electrodes.