Double stacking solar cells in a bifacial solar module could lead to higher efficiency
Researchers from Pakistan’s Lahore University and Egypt’s Benha University have proposed doubling the efficiency of current standard solar panels by going beyond the cutting-edge perovskite-silicon tandem solar cell in an increasingly common bifacial format.
The scientists beleive that their combination of materials can reach into the high 20 percent range in the standard single-side format, to which they then add a second layer of that solar cell and place it all within a glass on glass solar module. The bifacial solar module will boost the cell’s total electricity output by 10 to 30 percent, arriving at somewhere between 30 to 36 percent efficiency.
This research is presented in a paper is titled High-Performance Bifacial Perovskite/Silicon Double-Tandem Solar Cell, and can be found in the most recent issue of the IEEE Journal of Photovoltaics.
The top solar cell layers absorb most of the direct sunlight and shows an efficiency of 27.7 percent, with perovskite and silicon subcells having 16.5 percent and 11.2 percent efficiencies, respectively. The bottom solar cell mostly absorbs the albedo, or reflected sunlight, and shows an efficiency of 5.4 percent at 30 percent reflection, with perovskite and silicon subcells having 3.2 percent and 2.2 percent efficiencies, respectively. At the comfortable 30 percent albedo, the solar module peaks at a total 33.1 percent efficiency.
As the solar panel moves above an albedo of 30 percent, the equivalent of light sand, and moves toward that of a white rubber EPDM roof, which has an albedo well above 40 percent, the solar cell becomes saturated with photons and maxes out. Further refinement, such as varying the thickness of cells, could allow for continued gains in efficiency on the backside of the solar cell driving the whole solar panel toward 36 percent efficiency.