At present, most of the commercially available single-sided solar cells can convert sunlight to energy at an average efficiency of around 21%. This is very low. For comparison, internal combustion engines convert fossil fuel to power at an efficiency above 35%. Thus, there is a lot more potential when it comes to solar cell energy conversion. Bifacial panels can provide efficiencies up to 40%. However, they are just two-sided solar panels that also convert, the otherwise lost, diffused, and scattered solar irradiation in the visible spectrum. Theoretically, single-junction cells have a limit between 29 and 3%, called the Shockley-Queisser limit.
New Study on low energy light
The efficiency of many solar energy conversion technologies is limited by their poor response to low-energy solar photons. One way for overcoming this limitation is to develop materials and methods that can efficiently convert low-energy photons into high-energy ones. New research hints at the possibility of transforming low-energy light (invisible light) to high-energy photons that can be captured by solar cells. This process converts light that is less energetic than the near Infrared through a photochemical upconversion with oxygen. RMIT University, UNSW University, and the University of Kentucky (USA) lead this study.
Another approach in the research of high efficiency solar cells comes from the Okinawa Institute of Technology. Instead of silicon, perovskites are using in this technology. Such cells are economic and lightweight. In general, the main bottlenecks of perovskites-based solar cells include scalability and life span. Any defects in materials get amplified during the scale-up and result in poor efficiency as compared to silicon-based cells. Furthermore, perovskites-based cells degrade faster resulting in a smaller life span. The Okinawa research team used a multi-layer perovskites set-up. This performed at an efficiency of 16.6% (for size of 22.4 sq. cm) for a time of 2000 hours operational time.