Research On Test System For Multi-junction GaAs Solar Cell

The solar cell test system plays an important role in evaluating the performance of solar cells and improving the manufacturing process of solar cells,especially the laminated solar cells with high efficiency but complex structure such as multi-junction GaAs solar cells.In this paper,the multi-junction GaAs solar cell test system is studied from the aspects of test principle,test system software and hardware and system performance analysis.This paper analyzes the structure and equivalent circuit model of multi-junction GaAs solar cell,discusses the test method of I-V characteristics of solar cell,and focuses on the problems and solutions in the spectral response measurement of multi-junction GaAs solar cell.The multi-junction GaAs solar cell test circuit is designed,including linear power supply circuit,I-V characteristic test circuit and spectral response characteristic test circuit.The linear power supply circuit is used to generate the system voltage supply,bias voltage and reference voltage of test circuit.STM32F103RET6 is responsible for communicating with computer test software,controlling I-V characteristic test circuit and spectral response characteristic test circuit and reading data from these test circuits.The I-V characteristic test circuit measures the voltage and current data of the solar cell from the open circuit to the short circuit state by using MOSFET characteristics.The short-circuit current is processed to calculate the SR(λ)and EQE by the spectral response test circuit based on the I-V characteristic test circuit.The multi-junction GaAs solar cell test software,which is consist of embedded program and LabVIEW program,is designed.The main functions of embedded program are receiving order from LabVIEW,uploading data to LabVIEW,controlling the test circuits and reading data from them.The LabVIEW program provides the user Interface and shows the test results which can be stored or imported.Finally,the main functional modules of the multi-junction GaAs solar cell test system is tested.Among them,the standard deviation of the open circuit voltage measurement of the I-V characteristic test system is 5.099,the relative error of voltage measurement is 0.5%,and the relative error of current measurement is 2%,which achieves the expected goal.The test system measures the short-circuit current of top and middle cells with wavelength change,which verifies the feasibility of spectral response measurement method for multi-junction GaAs solar cells.