A photovoltaic system with three solar cells and a band-stop optical filter

Abstract

One approach for designing high-efficiency photovoltaic systems is to use several solar cells. One technique is to stack several solar cells with different energy band gaps on each other and concentrate sunlight on them, but the technical challenges and the manufacturing cost increase as the number of cells increases. Another technique is to keep the cells apart and split the sunlight into different sub-beams and direct the sub-beams toward separate cells, which are made of semiconductors with specific energy band gaps. In this study, we are proposing a novel photovoltaic system that combines both approaches for the sake of reducing the manufacturing cost of the system and increasing the efficiency. The system involves three solar cells: two cells are made of GaAs (1.42 eV) and Ge (0.66 eV), which are almost lattice matched, and the other cell is made of Si (1.12 eV), which is kept apart because it is not lattice matched to the two other cells. Different from the systems reported in literature, the proposed system involves a band-stop optical filter instead of a low-pass optical filter. This approach demonstrates the use of double-junction cells made of lattice matched materials, while the top cell has a high energy band gap (GaAs) and the bottom cell has a low energy band gap (Ge). In this paper, we describe the architecture of the proposed system, its features, the modeling approach adopted, and the system performance under the standard conditions.