Researchers at Italy’s CNR developed a four-terminal PV tile that uses spectral splitting to direct visible and infrared light to GaAs and bifacial silicon cells, respectively. Outdoor testing confirmed reduced self-shading and enhanced albedo collection, while highlighting opportunities to improve optical efficiency and advance the technology toward commercial applications.
Researchers at the Italian National Research Council (CNR) have developed a four-terminal (4T) photovoltaic tile that uses spectral splitting to direct different portions of the solar spectrum to the cells best suited to convert them. The system directs visible light to a gallium arsenide (GaAs) cell and infrared radiation to a bifacial silicon cell.
“The innovation of the patented new design relies on the use of an optical core in the shape of a wedged right-angled glass prism,” corresponding author Floriana Morabito told pv magazine. “Overall, the optical core acts as a light guide through a combination of total internal reflection (TIR) at the top surface and dichroic reflections at the mirrors.”
“The optical design is such that the rear side of the bifacial narrow-bandgap (NBG) silicon cell faces south, boosting the collection of albedo irradiation,” added co-author Silvia Maria Pietralunga. “At the same time, the 90-degree orientation of the wide-bandgap (WBG) GaAs cell minimizes land use and module self-shading.”
