Concentrated pv cell focus sunlight several times, tens of times, hundreds of times or even thousands of times with convex lens or parabolic mirror, and then project it onto solar cells. At this time, the solar cell may produce electricity.The corresponding multiple of electric power is obtained. They have the advantages of high conversion rate, small battery area and less consumables. Gallium arsenide (GaAs) solar cells are representative of high power concentrated pv cell.
The development of concentrated pv GaAs solar cells began in the 1950s and has a history of more than 50 years. In 1954, it was found that GaAs has photovoltaic effect.
In 1956, loferski J. J. and his team explored the physical properties of good materials for manufacturing solar cells. They pointed out that the materials with eg in the range of 1.2-1.6 EV have high conversion efficiency（ The eg of GaAs material is 1.43 ev. Within the above high efficiency range, the efficiency of GaAs single junction solar cell can reach 27% theoretically. In the 1960s, gobat et al. Developed the first Zn doped GaAs solar cell, but the conversion rate was only 9% ～ 10%, far lower than the theoretical value of 27%. Soon after, HRL (Hughes Research Lab) and Spectrolab of the United States improved LPE technology to make the average efficiency of the battery reach 18%, and achieved mass production, creating a new era of high efficiency GaAs solar cells.
Since the 1980s, GaAs solar cell technology has gone through several development stages from LPE to MOCVD, from homoepitaxial to heteroepitaxial, and from single junction to multi-junction stacked structure. Its development speed is accelerating, and its efficiency is also improving. At present, the laboratory efficiency has reached 50% (data from IBM), and the industrial production conversion rate can reach more than 30%.