Solar power has the potential to transform the world’s energy supply: More solar energy hits the Earth in one hour than the whole world uses all year. One of the main hindrances of using this energy has been the conversion efficiency of solar collectors. Today’s conventional solar panel can convert only 15-20 percent of received sunlight into electricity. A 50 percent conversion rate is the mythical number to achieving grid parity that experts claim will revolutionize the solar industry.
As with many renewable energy innovations, scientists are figuring out how to develop an increasingly efficient solar cell. Sharp Corporation has just achieved an efficiency milestone of 43.5 percent, surpassing their previous record of 36.9 percent efficiency. The triple-junction compound solar cells are made of three layers of photo-absorptive materials constructed from a combination of rare elements such as indium, gallium and arsenide. The cells are placed under a lens system that focuses sunlight onto the conversion materials. Efficiency was also gained by optimizing the spacing between electrodes on the surface of the concentrator cell and minimizing the cell’s electrical resistance.
Triple-compound solar cells are already in use, primarily on space satellites, but Sharp hopes to bring this technology back to Earth by developing concentrator photovoltaic power systems that are able to use small-surface-area solar cells.
This latest version of Sharp’s compound solar cell was a product of an R&D project through Japan’s New Energy and Industrial Technology Development Organization (NEDO). The recorded value of 43.5 percent efficiency was independently confirmed by the Fraunhofer Institute for Solar Energy Systems (ISE) in Germany. Interestingly, the U.S. company Solar Junction achieved the exact same conversion efficiency in March 2011 with their multi-junction solar cell technology.
Both of these examples are a good sign that brighter times are ahead for solar energy efficiency.
Image credits: Sharp Corporation