The National Renewable Energy Laboratory (NREL) and the U.S. Thin film PV manufacturer First Solar were able to design Cadmium telluride (CdTe) bifacial solar panels. With these panels, the scientists are claiming to achieve the highest power density than any available polycrystalline absorber available in the market. The composition of these bifacial CdTe solar cells involves a buffer containing copper, gallium, and monoxide (CuGaOx). The scientist makes use of the cracked film lithography (CFL) patterned metal grids in order to incorporate the rare interference buffer into the bifacial CdTe solar cells.
The CFL is not only cost-effective but also can withstand the application of high-resistance materials like CdTe. This was the prime reason to ditch the common passivating layers’ like oxides of aluminum and other metals. This research paper “Cracked Film Lithography with CuGaOx Buffers for Bifacial CdTe Photovoltaics”, was published in “NANO MICRO SMALL”. Researcher Chris Mazzillo describes that the only reason to select CFL over photolithography was its ability to lower the material and equipment cost for patterning metal grids in III-V photovoltaics.
Moreover, the CuGaOx/CFL grid samples were able to produce high open circuit voltage for the solar cells in comparison to their gold(Au) covered areas. The augmentation in the fill factor of devices also takes place from 70.8% to 73.3%.
The previous CdTe bifacial panels had front and rare efficiencies of about 12.5% and 7.6% respectively. While the CFL grids were able to increase the front power density by 39% and rare density by 25%. However, the rare efficiency of Bifacial CdTe solar cells still remains low in comparison to silicon bifacial panels. Muzillo is adamant to elevate the rare and front efficiencies for Bifacial CdTe solar cells soon.
