ilicon solar cell is the mainstream of solar power generation technology at present, but at the current large-scale commercial technology, its conversion efficiency is expected to hardly more than 23%.The continuous development of various technical and research unit, to breakthrough the efficiency of the ceiling;Confirmed the latest public technology, the solar cell efficiency can be above 30%.
Fraunhofer institute of solar energy systems (ISE) and the Austrian company EV Group (EVG) cooperation, success on the basis of silicon solar cells, and have more than two electrodes of the junction solar cell technology, make the solar cell conversion efficiency high to 30.2%.
Fraunhofer ISE and EVG researcher through direct epitaxial wafer joint (direct wafer bounding) technology converts micron grade five families of the semiconductor material silicon;After the plasma activation on the surface of the epitaxial wafer battery (subcell) will present vacuum joint, make three atoms on the surface of the battery and the silicon atoms tight joint, formed on the basis of the silicon battery.
Three to five family of semiconductor/silicon junction solar cell current and voltage variation curve.
At present, this kind of 35 of semiconductor/silicon joint battery costs remain high, 35 semiconductor epitaxial engineering and joint technology has cost down space.Researchers at the Fraunhofer ISE said will continue to study, to promote the conversion efficiency more than 30% of the solar energy components.
Sharpe similar technology, used in satellites and coffee chairs
As well as joint technology to develop more efficient solar cells, and their Sharp (Sharp).Sharp NEDO cooperation with Japan in May this year public research, through the three joint compound technology makes the conversion efficiency up to 31.17% of the solar photovoltaic cells, is currently the world's highest conversion efficiency technology.
Sharp's three joint compound battery cascading indium gallium phosphide, gallium arsenide and indium gallium arsenide (InGaAs) and so on three layers structure suction light, and in a special tunneling junction layer and buffer layer with combination among them, the battery can absorb the spectrum of a wider, absorption efficiency is higher.
Sharp's compound three junction solar cells, record conversion efficiency is 31.17%.(source: Sharp)
Sharp published in May by 31.17% efficiency record for 986 square centimeters of large batteries;But before that, the same technology in small area of 1.047 square centimeter batteries create 37.9% of the technical efficiency.
In the past, sharp on this technology was applied to the satellite, but in October, the sharp applied to coffee chair, and connecting with the battery charged and USB port, create special solar charging chair, has set up three Starbucks outlets in Tokyo.