Sharp’s latest multi-junction PV cell recently set the new record for PV cells of all types by reaching 44.4 percent sunlight to electric conversion efficiency. That surpasses the previous record set by Solar Junction, which reached 44 percent conversion efficiency in October 2012.
With the latest record Sharp now holds the records for triple-junction PV cells both under concentration and without concentration. In April, the company reported that it exceeded the 37.7 percent conversion record for a PV cell under no concentration that it had set in 2012. That PV cell reached 37.9 percent conversion efficiency. That cell efficiency was confirmed by Japan’s Institute of Advanced Industrial Science and Technology (AIST).
However, these cells are much more expensive than conventional PV cells, since they use rarer, more expensive photoreactive materials. “Sharp's concentrator triple-junction compound solar cells use a proprietary technology that enables the efficient conversion of sunlight into electricity by means of a stack of three photo-absorption layers, the bottommost of which is made from InGaAs (indium gallium arsenide),” the company said.
That proprietary blend allows them to capture more of the sun’s light than they otherwise could. As such they’re usually designed for high-performance needs, like satellites. “Looking to the future, Sharp aims to harness this latest development success and make the use of compound solar cells more feasible in terrestrial applications,” the company said. Such terrestrial applications are likely for use in concentrator PV systems, like those designed by Amonix, which can concentrate the sunlight hitting the cell by hundreds of times using inexpensive Fresnel lenses.
The performance of the latest cell was evaluated by the Fraunhofer Institute for Solar Energy Systems (ISE) in Germany. ISE tested the cell under the concentration of 302 suns and reached the new efficiency level.
Sharp’s latest cell designed were supported by Japan's New Energy and Industrial Technology Development Organization (NEDO) through its ‘R&D on Innovative Solar Cells’ project. Sharp researchers were able to achieve the higher conversion efficiency by widening the effective concentrator cell surface to ensure uniformity of width at the interface of the connecting concentrator cell and electrodes, the company said.
There’s no telling how long Sharp will own the record. Solar Junction, for instance, has already announced its roadmap to CPV cells that are 50 percent efficient, as has Soitec, whose four-junction PV cell recently debuted at 43.6 percent efficiency under the concentration of 319 suns.