Abstract: Presently the researches on performance of GaAs solar cell using high concentrators have mainly been conducted under the condition of indoor simulating light source. However, there are few studies conducted in outdoor conditions. In this article, a small-scale Fresnel concentrating system is designed and built for experiment. Then, the system’s compositions as well as operating principles are introduced. According to the result, the geometric concentrating ratio is 500 and the radiation peak value reaches 948 W/m² at 13:00. The value of short-circuit current of a single solar cell is magnified to 253 times by using the concentrator while the value of open-circuit voltage increases by 0.34 V and the temperature of the solar cell’s back is 86.6 ℃. When shortcircuit gets the peak value, open-circuit voltage can not reach the peak value for the increase of chip’s temperature. The peak value occurs at 10：30 am and its value is 2.85 V. The open-circuit voltage has 0.03 V more than the value of radiation at peak. In this case, the temperature of the solar cell’s back reaches 74.4 ℃.

Key words: concentrator； triple-junction GaAs cell； short-circuit current； open-circuit voltage