Scientists at the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) have made a breakthrough in solar cell technology with the development of a bifacial perovskite solar cell. This innovation allows sunlight to be captured on both sides of the device, promising higher energy yields at lower overall costs.
The dual nature of the bifacial solar cell allows it to capture direct sunlight on the front and reflected sunlight on the back, surpassing the performance of conventional monofacial cells. The researchers published their findings in the journal Joule, titled “Highly efficient bifacial single-junction perovskite solar cells.”
Kai Zhu, a senior scientist at NREL and lead author of the paper, highlighted the cell’s exceptional operating capabilities from either side. The lab-measured front-side efficiency exceeded 23%, while the back-side efficiency reached about 91%-93% of the front efficiency.
Before constructing the cell, the researchers utilized optical and electrical simulations to determine the optimal thickness of the perovskite layer on both sides. The front layer needed to absorb most of the photons from the solar spectrum while avoiding blockage, while the rear electrode required a specific thickness to minimize resistive loss.
Through simulation-guided design, the researchers found the ideal thickness for the perovskite layer to be around 850 nanometers. This breakthrough eliminated the need for costly and time-consuming experimental iterations.
In testing the efficiency gained through bifacial illumination, the researchers placed the cell between two solar simulators. The front side received direct light, while the back side was exposed to reflected light. The cell’s efficiency improved as the ratio of reflected light to front illumination increased.
While the initial manufacturing cost of a bifacial perovskite solar module may exceed that of a monofacial module, researchers predict the former to be a better financial investment in the long run. Bifacial modules have the potential to generate 10%-20% more power, making them economically favorable over time.
Funding for this research was provided by the U.S. Department of Energy Solar Energy Technologies Office. NREL, operated for DOE by the Alliance for Sustainable Energy LLC, serves as the nation’s primary laboratory for renewable energy and energy efficiency research and development.