System and method for detecting leakage current of solar cells damaged by photovoltaic hot spots

Abstract

The invention discloses a system and method for detecting photovoltaic hot spot damage solar cell leak currents. The method includes the steps that the distribution condition of the reversal biasing leak currents is determined by testing the temperature change condition of solar cells under the reverse bias voltage; the cells are classified according to the reverse leak currents; meanwhile, distribution of the reverse leak currents of the solar cells is detected through infrared heat phase scanning, and the cells with the large local leak current density are selected. By means of the system and method, the solar cells with the large local leak currents are selected, and the excessively-high-temperature hot spot problem is solved under the voltage reversal biasing condition caused by current mismatching in the practical use of the solar cells.

Description

technical field [0001] The invention relates to a system and method for detecting leakage current of a solar cell damaged by a photovoltaic hot spot, and belongs to the technical field of photovoltaic cell detection. Background technique [0002] With the rapid development of the domestic solar photovoltaic industry and the rapid growth of photovoltaic system installation capacity in recent years, the operational safety and reliability of photovoltaic systems have gradually emerged. [0003] The environment in which photovoltaics are used varies greatly, and different environmental factors such as radiation, temperature, humidity, etc. have different impact mechanisms on the performance of solar cells and module packaging materials. Among them, according to the performance evaluation of photovoltaic modules according to the international standard IEC 61215, test environments such as hot spots, humid heat aging, and high and low temperature cycles cause high failure rates of ...

AI Technical Summary

Problems solved by technology

[0004] Under non-uniform irradiation, the output current of a single solar cell under lower irradiation becomes smaller, so that its two ends are reverse-biased, resulting in local overheating, which is the hot spot phenomenon, which will consume the power of the component In severe cases, it may even cause permanent failure of photovoltaic modules

At present, some photovoltaic research, testing institutions and photovoltaic enterprises in China have also carried out some photovoltaic reliability test evaluations and research on hot spot solutions, such as: adding multiple bypass diodes to protect solar cells. Due to the high cost of bypass diodes, There are also reliability problems in itself, and the promotion of this method has great limitations; at the same time, when the solar cell is severely reverse-biased, the bypass diode used to protect the solar cell and prevent it from generating an excessively high bias voltage will be at a low level. In the forward working state, a large amount of heat is generated so that the diode junction temperature can reach above 100°C, and long-term operation will also cause reliability problems

In addition, when the performance of the bypass diode fails due to long-term high-temperature operation, it cannot protect the reverse-biased solar cell, resulting in an increase in the voltage at both ends of the battery, generating a large amount of heat, causing more serious solar cell breakdown and burning problem

In addition, solar cell manufacturers reduce the leakage current value under the reverse bias voltage of solar cells by sorting methods. This method can partially reduce the hot spot problem, but due to the uneven distribution of reverse leakage current of solar cells, some low leakage currents For batteries, the leakage current is concentrated in a few local points or even one point, which will still cause hot spot problems, and there is no completely effective solution in terms of hot spot reliability

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