Reduce the hidden crack of photovoltaic modules, what is the hidden crack of photovoltaic modules, a

The first floor is solved, and I will be divided into two points. The crack is basically due to.

The quality of the silicon wafer is getting thinner and thinner, which makes the cell quality worrying, especially in the peak season, the power of the cell is okay, and the hidden crack is not so particular. Personally, I feel that this is the main reason and an uncontrollable factor for many module manufacturers without cell production lines, after all, this thing seems to be a seller's market when the peak season comes.

During the welding process, the welding equipment is not up to standard, there is tin slag, and the laminator crushes or illuminates the cell into a hidden crack when vacuuming.

Laminator issues.

Besides, it seems that everyone is mainly concerned about the power of modules, although hidden cracks will have a greater impact on the power attenuation of modules, but if you really give a standard for hidden cracks, it is estimated that module factories will die. If you want to solve the problem, it is better to improve the proficiency of workers and understand the characteristics of the use of existing equipment, after all, the upstream part is not something we can influence.

Causes of hidden cracking of solar PV modules.

There are the following causes:1The welding of the cell is uneven, and there is a pile of tin or slag, which crushes or cracks the cell during vacuuming; 2.The upper chamber of the laminator is deflated too quickly.

Workaround:1Check the string quality before lamination; 2.Adjust the lamination and curing process.

Dare to ask the eldest brother, you are also a ??? in the photovoltaic industry

1. What is the hidden crack of photovoltaic modules?

Hidden crack refers to the hidden crack that may occur in the cell cell that is not visible to the naked eye when the cell (module) is subjected to large mechanical or thermal stress.

According to the shape of the cracks, the cells can be divided into five categories: tree cracks, comprehensive cracks, oblique cracks, cracks parallel to the busbar, perpendicular to the busbar and cracks throughout the cell.

2. The impact of hidden cracks on photovoltaic modules.

The current generated by the cell is collected and exported by "the main busbar on the surface and the thin busbar perpendicular to the busbar". When the crack breaks the fine busbar, the fine grid cannot deliver the collected current to the main busbar, which will cause some or even all of the cell to fail.

Based on the above reasons, we can see that the biggest impact on the function of the cell is the hidden crack parallel to the busbar. According to the results of the study, 50% of the failed sheets come from hidden cracks parallel to the busbar.

The efficiency loss of a 45° inclined crack is parallel to the loss of the busbar 1 4.

Cracks perpendicular to the busbar hardly affect the fine busbar, so the area of cell failure is almost zero.

Compared with the grid on the surface of crystalline silicon cells, the surface of thin-film cells is covered with a transparent conductive film as a whole, so this is also one of the reasons why thin-film modules have no cracks.

Studies have shown that when the module crack is severe, it will lead to the loss of module power, but the size of the loss is not necessarily. The crack has little impact on the electrical performance of the module, while the splinter has a very large power loss on the module. Aging test, that is, the temperature and humidity changes of the module in working or non-working conditions may cause the aggravation of cell cracking; Cells without cracks in the module are more resistant to aging than cells with cracks.

3. How to detect hidden cracks in photovoltaic modules.

EL (electroluminescence) is a simple and effective method for detecting hidden cracks. The detection principle is as follows.

The core part of the cell is the semiconductor PN junction, which is in a state of dynamic equilibrium in the absence of other excitations (e.g., light, voltage, temperature), and the number of electrons and holes remains relatively stable.

If a voltage is applied, the internal electric field in the semiconductor will be weakened, and the electrons in the n-region will be pushed to the p-region, recombined with the holes in the p-region (it can also be understood as the holes in the p-region are pushed to the n-region, and recombined with the electrons in the n-region), and then recombined in the form of light, that is, electroluminescence.

When a forward bias voltage is applied, the crystalline silicon cell emits light with a wavelength of about 1100nm, which belongs to the infrared band, which cannot be observed by the naked eye. Therefore, in the EL test, these photons are captured with the help of a CCD camera, which is then processed by a computer and displayed as an image.

When a voltage is applied to a crystalline silicon module, the more electrons and holes are recombined, the more photons are emitted, and the brighter the measured EL image becomes. If the EL image of the region is dark, it means that the number of electrons and holes generated in the area is small, which means that there is a defect in the area. If the area is completely dark, it means that there is no recombination of electrons and holes, or the light emitted is blocked by other obstacles, and the signal cannot be detected.

1. The concept of hidden crack will not be repeated, focusing on the scheme of measuring hidden crack, the most professional should be to use EL tester (electroluminescence), pass the reverse voltage to the component, shoot the component through a special camera, and the dark part can see the hidden crack.

2. At present, most of the manufacturers' EL testers on the market can only be used at night or in tents, and only one SZS can be tested during the day, but it is also expensive, suitable for the full inspection of EL of super-large power stations, and the efficiency is not generally high.

Cause of reticular fissures.

1.The cell is caused by external force during welding or handling.

2.The cell is not preheated at low temperatures, and suddenly expands after being exposed to high temperatures in a short period of time, resulting in hidden cracking.

Component Impact: 1Mesh cracks will affect the power attenuation of the module.

2.Preventive measures that directly affect the performance of the module such as fragments and hot spots for a long time in the reticulated cracks

1.During the production process, the cell should not be too affected by external forces.

2.During the soldering process, the cell should be kept warm (hand welded) in advance, and the temperature of the soldering iron should meet the requirements.

The test should be strictly required to be inspected.

Usually the causes of hidden cracking of photovoltaic modules are:

1.The cell is caused by external force during welding or handling.

2.The cell is not preheated at low temperatures, and suddenly receives high levels in a short period of time.

After the temperature, there is an expansion, resulting in a hidden crack.

The impact of module cracking on the module itself is as follows:

1.Mesh cracks will affect the power attenuation of the module.

2.Fragments appear in the network cracks for a long time, and hot spots appear that directly affect the performance of the module.

Precautions to avoid cracks in components:

1.During the production process, the cell should not be too affected by external forces.

2.During the soldering process, the cell should be insulated in advance, and the temperature of the soldering iron should be.

Meets the requirements. The test should be strictly required to be inspected.