What are the characteristics of photovoltaic module failure?

Common aging phenomena of crystalline silicon modules include cell fragmentation, hot spots, EVA yellowing, backplane cracking, snail lines, etc., which are visible to the naked eye. Although hot spots, junction box cold soldering, diode failure, and electrothermal induced attenuation are not visible to the naked eye, they will cause serious uneven heating of the cells inside the module and a significant decrease in power generation, which can be detected by technical means. Through regular inspections of the modules and tracking of power generation, if obvious abnormalities are found in the appearance of the modules or a sudden and significant decrease in power generation, it is suspected that the modules may fail. It is recommended that photovoltaic power stations with conditions be equipped with infrared thermal imagers to quickly detect and locate problematic modules by detecting the temperature difference of the film on the surface of photovoltaic modules. After discovering that the module has failed, please contact the manufacturer in time for analysis and processing, and do not repair the failed module by yourself.

1. The appearance of snail lines is a comprehensive process. Factors such as the additives in the EVA film, the silver paste composition on the surface of the cell, the hidden cracks of the cell, and the catalysis of water in the system will promote the formation of snail lines. The appearance of snail lines is not inevitable, but has its accidental triggering factors. The EVA film formula contains crosslinking agents, antioxidants, coupling agents and other additives. Among them, crosslinking agents generally use peroxides to initiate the crosslinking of EVA resins. Since peroxides are highly active initiators, if there are still a lot of crosslinking agents left after lamination, it will have an initiating and accelerating effect on the formation of snail lines.

The additives used in the film have purity indicators, and generally speaking, the purity requirement must be above 99.5%. The impurities in the additives are mainly by-products and additive residues in the synthesis. They exist in a small molecule state and have a high boiling point. They cannot be removed from the system by laminating vacuum. Therefore, if the purity of the additives is not high, these impurities will also affect the stability of the EVA film and may cause the appearance of snail lines.

2. EVA delamination

The degree of crosslinking is unqualified. (For example, the temperature of the laminator is low, the lamination time is short, etc.) Caused by foreign matter on the surface of raw materials such as glass and backplane.

The uneven composition of raw materials (such as ethylene and vinyl acetate) leads to delamination due to inability to dissolve at normal temperature.

Excessive use of flux, long-term exposure to high temperatures outside, resulting in delamination of the main grid line.

3. Poor silicone leads to delamination and hidden cross cracks in the cell

Unqualified crosslinking, such as low laminator temperature, short lamination time, etc., caused by foreign matter on the surface of raw materials such as glass and backplane.

There are gaps in the frame glue, and after rainwater enters the gap, the component heats up during long-term operation, causing delamination at the edge of the component.

Hidden cracks caused by external forces on the cell or component.

4. Burned components

The contact area between the busbar and the welding strip is small or the resistance increases due to false welding, causing the component to burn.

5. Fire in the component junction box

1. The lead is not clamped in the slot, causing sparks and fire.

2. The welding area of the lead and the junction box solder joint is too small, resulting in excessive resistance and fire.

3. The lead is too long and contacts the plastic parts of the junction box for a long time, which will cause fire.

6. Battery cracks

1. Improper operation during welding causes cracks.

2. The incorrect lifting and placing techniques by the personnel caused the component to break.

3. The laminator failed and the component flakes.