PERC Solar Cell EL Tester And Study On Aluminum Back Field Performance

As a promising clean energy,photovoltaics solar cells have been used more and more widely.By the end of 2017,China has installed a total of 130GW solar cell module,becoming the largest country in the production and application of solar cells.Crystalline silicon solar cells have the advantages of high conversion efficiency,suitable for large-scale industrial production,long-term work stability,etc.,accounting for more than90%of the entire solar cell.PERC?Passivated Emitter and Rear Cell?silicon solar cells have an efficiency increase of about 1.0%compared with ordinary silicon solar cells,which is a hotspot in the recent research of solar cells.Since the back surface field of the PERC solar cell is local contact,the aluminum back field is prone to defects such as corrosion of the passivation layer and generation of voids.In this paper,a test system for analyzing the EL characteristics of PERC cells was designed,and the effect of the glass frits in the aluminum back surface field on the performance of PERC solar cells was studied.Based on the principle of electroluminescence?EL?,the structure of the EL tester was designed.The EL tester is mainly composed of a black box,an industrial CCD camera,a DC constant voltage source,contact probe,and a computer.The collected EL image is very clear and bright.The paper completed the software development for EL testing.The MFC control based on Visual Studio completes the interface setting,and successfully acquires the image data of the camera by calling the camera SDK development kit.The EL image is analyzed and processed by Matlab and Halcon software.The developed software can identify cell defects such as black spots and black lines in EL images.It provides an effective experimental means for EL characteristic analysis of PERC cells.PERC silicon solar cells were prepared by V-B-metal oxide?V-B-MO?glass frits with different V₂O₅-B₂O₃ ratio.The cell was tested by electrical properties test,SEM and electroluminescence?EL?.The differential thermal analysis of the glass frits was carried out to study the effect of V-B-MO glass frits on the local back field performance of the PERC cells.The results show that when the V-B ratio of the glass is 25:35%by weight,the cell has a higher open circuit voltage and conversion efficiency.By adding rare earth element oxides La₂O₃,CeO₂,etc.to V-B-MO glass,the electrical properties of the cell can be improved.In the V-B weight ratio of 25:35%,adding 38.8 wt%of MO?MO=Al2O3+BaO+ZnO+SrO?and 2.9 wt%of CeO₂,the glass frit has a melting point of 532.35°C,and no obvious melting temperature zone.The efficiency of the cell is high,reaching19.47%.There are three states of filling at the local aluminum back field,full filling,partial filling and no filling,and a poorly filled part will produce black lines in the EL image.