Crack Solar Panel: Causes, Detection and Prevention

Crack Solar Panel can reduce the energy output of a solar PV system by decreasing the short circuit current and overall efficiency of the cells. These cracks can form due to various factors such as mechanical stress, thermal stress, and environmental conditions like temperature changes, humidity, and wind loads.

The formation of micro-cracks can be prevented by improving the quality control process and using appropriate materials. ELCD (electroluminescence crack detection) testing is one of the common methods used to detect micro-cracks, however, it is not always used by all PV manufacturers due to the cost and time required for testing. The presence of micro-cracks can also affect the warranty coverage of the system and is usually stated in the policy endorsement.

Manufacturing solar photovoltaic (PV) modules is a complicated challenge due to frequent micro cracks. Although it's difficult to determine their exact impact on a solar panel's efficiency and longevity, they are a leading cause of malfunction or inactive cells.

Despite efforts to prevent micro cracks, they are almost unavoidable and will eventually affect most solar panels, even high-quality ones. The cracks are caused by various environmental factors such as hail, snow, sun, wind, and extreme cold, as well as the thermal cycles of the cells that involve metal contacts, solder, and wire interconnects contracting, expanding, and flexing.

How do micro-cracks occur?

Manufacturing defects can be caused by poor quality control or process issues.

Micro-cracks in solar PV systems can be caused by environmental factors such as thermal cycling, changes in humidity and temperature, wind loading, heavy snowfall, and hail.

Potential Impacts of Micro Crack Solar

The potential impacts of micro cracks are significant and should be addressed and minimized as early as possible.

However, this is often not adequately addressed during quality control at many manufacturers.

[caption id="attachment_2182" align="aligncenter" width="215"] Solar panel micro crack[/caption]

Micro cracks can be detected using Electro Luminescence Crack Detection (ELCD) test and have various defect origins that can result in mild to severe outcomes. The mild outcomes can lead to reduced yield by shading parts of the affected cell, while the severe impacts can result in decreased short circuit current and cell efficiency.

These cracks are often caused by mechanical forces or thermal stress, with most of them occurring during panel lamination, particularly when using EVA films with weak moisture resistance. If moisture enters through the micro cracks in such cases, it cannot easily evaporate, leading to oxidation of the contact fingers, especially in hot and humid environments.

Micro cracks in a mono-crystalline solar (PV) module

In a mono-crystalline solar (PV) module, micro-cracks can also occur during manual solar cell soldering, when temperature differences between the copper and silicon elements result in thermal expansions above 300°C. This can cause micro-cracks in the substrate and increase cell resistance.

Over time, these cracks can grow and have a negative impact on the functionality and performance of the PV module, potentially causing hot spots. If left undetected, they can lead to a shorter lifespan than expected, with varying size, location on the cell, and impact on quality.

[caption id="attachment_2183" align="aligncenter" width="300"] Micro cracks in a mono-crystalline solar (PV) module[/caption]

ELCD testing ideally should be done before and after the lamination process to detect and replace defective solar cells. This process requires time and manpower, which some PV manufacturers may not be willing to invest in to ensure the quality of their solar panels.

How to find and eliminate micro cracks in solar cells?

There are several methods to identify micro cracks in solar panels, one of which is Electroluminescence Crack Detection (ELCD) testing. It is also sometimes referred to as "solar panel x-ray scanning." ELCD testing is capable of detecting hidden defects that other methods such as infrared imaging, visual inspection, or flash test cannot detect.

This is because it is an imaging measurement process that allows for direct inspection of the cells of a PV module to locate potential defects. Micro-cracks can sometimes appear as "snail trails" on the cell structure, but snail trails can also be a result of chemical changes or hot spots, so visual inspection alone is not enough to identify micro-cracks. For this reason, a thorough ELCD check is necessary.

Insurance considerations

In the context of micro-cracking in solar PV systems, insurance companies are taking a cautious approach by restricting coverage and establishing sub limits for micro-cracking. This is due to the negative impact that micro-cracks can have on the energy output and system lifetime of solar PV systems.

As a result, it is important for those in the renewables sector to have a full understanding of the coverage restrictions imposed by insurance companies. This knowledge can help individuals and organizations make informed decisions regarding insurance coverage and plan accordingly to mitigate risks associated with micro-cracking in their solar PV systems.

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