Experimental Test of High-Efficiency GaAs/Si HJT Four-Terminal Solar Cell System with Spectral Splitting

To overcome the limitations of conventional solar cells and to reach high-efficiency photovoltaic systems, the design of an innovative system that combines GaAs and Si cells with optical components is presented. The integration of GaAs and Si HJT in a 4 terminal solar cell system enhanced by spectral splitting represents a promising pathway toward high-efficiency photovoltaic devices. This system ensures that each cell absorbs the portion of the solar spectrum for which it is more efficient, reducing thermalization losses and enhancing the overall performance. In this work, a dielectric prism with light waveguide and transmittance capabilities, and a tailored dichroic mirror that reflects short and transmits long wavelengths, acting together as a spectral splitting system, were opportunely integrated with the semiconductor photovoltaic cells. The designed system was tested indoor and outdoor at different incident angles. The overall collection efficiency measured both indoor and outdoor matches. It was found that the angle with respect to the normal to the input surface which maximizes the overall collection efficiency of the system is α=10°, and it is around 93%.