2.1.2 The soaking time of the welding strip is too short

1) Reason. Due to long-term storage of the welding ribbon, the welding on the surface may be oxidized and deteriorate due to the influence of humid air. Therefore, before use, it needs to be cleaned with flux to remove surface contaminants and oxide layers. The typical soaking time is 5 to 8m. After soaking, the welding strip should be flattened and dried. It can be used after about 5m.

2) Solutions. If it is determined that the failure to weld is caused by insufficient soaking time, the soaking time of the welding strip can be extended to more than 10 minutes during soaking. At the same time, clean tweezers can be used to stir continuously during soaking to increase the cleaning effect.

2.1.3 Flux does not meet specification requirements or fails

1) Reason. When soaking the welding strip, you should use a no-clean flux with an ethanol purity of more than 98%. The ethanol purity is low and may contain other impurities, which will affect the cleaning effect. At the same time, the flux should be stored in a cool and dry environment. Avoid sun exposure; it should be stored in an environment with a temperature of -25°C to 18°C and a humidity of 74% to 85%. If the flux is opened for more than 3 months, it will also cause failure.

2) Solutions. If it is found that the welding ribbon cannot be welded due to the flux, the flux needs to be replaced and the welding ribbon needs to be soaked again.

2.1.4 The heating temperature of the welding iron and pad is set too low

1) Reason. When welding cells, the welding iron used is generally a special welding iron for solar cells with a power of more than 75W. The temperature of the welding iron is generally set at 350°C to 380°C according to the type of cells, and the temperature of the pad is set at 45°C to 50°C. ℃. If welding fails, it may be because the temperature of the welding iron or heating pad is too low.

2) Solutions. Properly increase the temperature of the welding iron and heating pad. When raising the temperature, raise the welding iron by 5°C each time. Wait until the temperature reaches the set value before welding. If you still cannot weld effectively, raise the welding iron by another 5°C. The maximum temperature can be raised to 400℃. If effective welding still cannot be performed, use a thermometer to test the actual temperature of the welding iron to see if the measured temperature is consistent with the set temperature. If not, the welding iron can be considered faulty and should be replaced.

2.2 Missing welding

After the welding of the cells is completed, it will be found that the welding tape is not welded in some places, resulting in a decrease in the photoelectric conversion efficiency of the cells. The main reasons for the leakage of welding are as follows:

1) The welding speed is too fast. For monocrystalline silicon cells, the typical welding speed is 2 to 3mm/s. If the welding iron tip slides over the welding ribbon too fast, the welding in some parts of the surface of the welding ribbon may not be fully melted, and the welding ribbon cannot be connected to the battery sheet. The surface grid lines are welded together.

2) The local area of the welding strip is contaminated. Before use, the welding ribbon should be soaked in flux to remove contaminants and impurities on the surface of the welding ribbon. However, it is also possible that local areas of the welding strip are more seriously polluted. During the same soaking time, surface contamination may not be completely removed, which will also affect subsequent welding, resulting in leakage welding.

3) The temperature of the welding iron is unstable. Before welding, first set the welding iron temperature to a suitable temperature and measure it with a thermometer. During the welding process, the temperature may fluctuate due to the failure of the welding iron itself. In this way, when the welding iron tip slides over the welding ribbon, the temperature of the welding iron tip may decrease in some places and the welding ribbon cannot be melted. This may also cause leakage. Weld.

If the leakage of welding is caused by the above reasons, it can be solved by the following measures:

1) Reduce the welding speed to completely melt the entire welding ribbon to ensure that the cell grid line is completely welded to the welding ribbon anywhere.

2) For welding strips where local dirt has not been removed and affects welding, you can use a sponge dipped in flux to wipe the area during welding, and wait until the flux evaporates before welding.

3) If the temperature of the welding iron is unstable, the welding iron needs to be replaced.