Spectral splitting module geometry that utilizes light trapping

Abstract

In this paper, we present a novel geometry for a photovoltaic module. This novel geometry employs light trapping effects to split the solar spectrum onto two different kinds of solar cells. The two different kinds of solar cells utilize different parts of the solar spectrum most efficiently. The proposed structure is based on prisms. The different kinds of solar cells are attached to opposing surfaces of the prisms. To achieve spectral selectivity, either spectrally selective filters or the solar cells itself are used. After introducing the general concept, we discuss different possible realizations. The theoretical potential of the light trap is calculated using the concept of spectral efficiency. Based on experimental solar cell data, we calculate theoretically that conversion efficiencies exceeding 30% are possible with such a module using silicon and GaAs solar cells. First experiments show that the optical losses of the proposed geometry are as low as 2.1% relative.