Utilization of Direct and Diffuse Sunlight in a Dye-Sensitized Solar Cell - Silicon Photovoltaic Hybrid Concentrator System

The concept of a tandem hybrid concentrator solar module was demonstrated from a dye-sensitized TiO2 solar cell (DSSCs) and a silicon p-n junction solar cell. The test system employed DSSC and Si cells with indoor AM1.5G efficiencies of 9.1 and 18.1%, respectively. Two different optical filters were used to selectively reflect and concentrate near-infrared light from the DSSC onto the Si cell. On the basis of outdoor testing in a 2 x concentrator reflector arrangement, the tandem system generated 93 and 96% of the output power of directly illuminated Si cells under altostratus/cirrostratus and clear sky irradiances, respectively, despite a DSSC-to-Si active area ratio of only 0.92. Similar performance is expected at higher (5-10 x) concentration ratios. The hybrid arrangement of visible- and IR-absorbing solar cells addresses the problem of lower performance of conventional concentrators under diffuse irradiance conditions. These proof-of-concept results suggest that system level efficiencies approaching 20% should be achievable.