The Research Based On Applications Of Electroluminescence Test In The Certification Of Crystalline Silicon Photovoltaic Modules

To accommodate the large-scale production and application of crystalline silicon solar cell, the importance of quality control in the field of PV(photovoltaic) modules are increasingly prominent. The electroluminescence test of crystalline silicon solar cells and modules is a test method which has been researched and applied in recent years. IEC (International electrotechnical commission) has been put forward that a testing standard for electroluminescence image of PV modules are urgent needed. At the same time, a standard are needed in our country which can confirm the test operation and results. Research in this thesis is a preparatory work for the domestic EL test standard.First, according to the test environment, including light intensity, temperature, flow, An EL test system of crystalline silicon solar cell was built which composed of CCD camera, DC power and other apparatus. Then, EL test operation and process were specified, including the camera settings and positioning, biasing, imaging and computer-assisted control during image capture.Then, the author analyze the reason cause the defect of PV modules, focus on the micro-cracks in cells and simulation the situation of one-line cracks in different positions in cells and point pressure of different sizes. Development program Under the Python with Opencv to calculate the failure area proportion in cells. In the experiment of one-line cracks in different positions, polycrystalline silicon cells involved in power decrease about10%, and monocrystalline silicon cells are1.7%to5.7%. In the experiment of point pressure, the power loss was about11%and4%, respectively. By compared the results of EL test and results of other parameters, these two typical damage’s effect to the crystalline silicon solar cells were identified. The judge standard about micro-cracks could be made.Finally, in practice, focus on the other defects in modules, a darkroom outside was built and a large number of PV modules were taken EL test. Short circuit current, open-circuit voltage, power and efficiency were amended by STC (standard test condition) and get the statistics testing data. The mean value of the modules which were identified micro-cracks, light and shade cells, bars break, black edges, black spots, broken cells had the power loss at6.34%,4.07%,5.49%,12.09%,6.77%,5.23%,10.15%, respectively.Through the research, in PV modules, the degree of influence of each type of defect was further identified by electroluminescence images. It could be a foundation about the EL test standard which can judge if the PV module was qualified and provided some theoretical and experimental basis for the preparation of the standard.