Experimental Study Of He Output Characteristics Of Triple-junction GaAs Cells Under Fresnel Lens Concentrator

The problem of energy crisis and environment pollution limits the development of the world economy. Thus, developing new energy source positively and seeking sustainable development of social economy are the main strategic mission of many countries. Solar energy is the most widely distributed kind of renewable energy source. Once it can be effectively and efficiently used, the energy crisis will be eased. As a result, solar energy will play a vital role in the future energy structure. In the process of developing and applying solar energy, photovoltaic power generation technology is paid attention. It is the scarcity of solar cell material as well as high cost of power generation that restricts utility of photovoltaic power generation. Therefore, reducing the expense is the bottleneck of photovoltaic technology. By cutting down the expense in proportion of the solar cell, concentrating photovoltaic technology is placed great expectation.Currently, the experimental study for GaAs cell’s capability are mainly based on indoor simulative light source condition. Whereas, there are comparably less experimental study performed outdoor. In this thesis, we design a small-sized Fresnel light-concentrating photovoltaic system, which includes Fresnel lens, total reflection type secondary condenser, Triple-junction GaAs cell, the sun tracker, Stepper motor etc.. And the system structure, working principles and outdoor experimental study are also introduced.The experimental results show that the solar radiation intensity increases gradually from morning to noon. And it will reach its peak value which is 948w/m2 at 13:00. The value of solar radiation intensity and short-circuit current of GaAs cell reach their respective peak simultaneously.In the condition that the geometry concentrating ratio of Frenel light-concentrating photovoltaic system are 1 time,3.61 times and 500 times, the short-circuit currents are 14.8mA,38.7mA,3.75A respectively. In the condition of 500 times spotlight, the value of short-circuit current of single solar cell is magnified by 253 times compared with the nature state; In the condition of 1 time and 3.61 times spotlight, the open-circuit voltage value of GaAs cell which comes to the maximum are 2.48V and 2.57V respectively. The variation of the open-circuit voltage value almost synchronizes with the variation of the solar radiation intensity value. The variation of the cell chip temperature is not drastic on account of low light-concentration. Because the open-voltage value logarithmic increases with solar radiation value and linear decreases with cell chip temperature value. The open-circuit value which is in condition of 500 times light-concentrating can not reach the peak value resulting from the augment of the chip temperature and its value is 2.82V which increases by 0.34V compared with the nature state. The peak value occurs at 10:30am. At that time, battery backplane temperature is 74.4℃ and voltage is 2.84V which increases by 0.03V compared with the counterpart which at the time when solar radiation value come to the maximum. The short-circuit currents are basically the same between the two Triple-junction solar cell in series and single Triple-junction solar cell. The latter’s voltage is twice as much as the former.