Foreword
"The solar panel was cracked by hail. Is it still usable? Should it be replaced?"
This is a common problem for many solar energy users. Solar panels are installed on rooftops or outdoors, exposed to wind, sun, and rain, and are inevitably susceptible to damage from hail, falling branches, and trampling. When a panel develops cracks, the user's first reaction is often concern: Will this thing still generate electricity? Are there any safety hazards? Should I spend money to replace it?
There's no single answer to these questions. Cracks in solar panels come in different types and degrees, and their impact on power generation efficiency and safety varies. Some cracks are merely superficial and don't affect power generation; others are more serious, leading to decreased power output or even safety hazards. This article will discuss in detail how cracks in solar panels develop, how to assess their severity, and how to address the four different levels of damage.
I. How do cracks form in solar panels?
Before discussing the extent of the damage, let's understand how cracks in solar panels form.
The most common cause is physical impact. Hail is the most typical culprit for cracks in solar panels. Hail falls from the sky and hits the glass panel. If the hailstones are large in diameter or dense, the impact force is enough to crack or even shatter the glass. Especially for aging solar panels, the glass surface may have tiny abrasions and scratches, making these areas less resistant to impact and more prone to cracking.
Besides hail, there are several other common causes. The first is cracks caused by thermal stress. When solar panels are repeatedly subjected to high and low temperatures, the different materials (glass, EVA film, cells, backsheet) have different coefficients of thermal expansion, which generates internal thermal stress. If this thermal stress accumulates over a long period, cracks may form in the glass or cells. These cracks usually start from the edges or corners, are long and thin, and are not easily noticed without close inspection.
The second type of crack is caused by installation pressure. Some solar panels are subjected to uneven stress during installation. For example, if the clamps or fixtures are installed too tightly, or if the brackets are uneven, local pressure may occur on the panel, which may lead to cracks after long-term operation. These cracks are usually distributed along the edges of the solar cells and have a relatively regular shape.
The third is impacts during handling and installation. Solar panels are fragile; if they are struck by sharp objects or squeezed by heavy objects during transportation, handling, and installation, cracks may occur. These cracks are usually located at the edges and corners of the panels and are irregular in shape.
The fourth type is cracks caused by aging. The lifespan of solar panels is typically 25 to 30 years. As the years of use increase, materials such as glass and EVA film gradually age and become brittle, reducing their impact resistance. These aging cracks usually start from the edges or interior of the panel and gradually extend outwards.
Understanding the causes of cracks helps you understand why some boards last for over a decade without problems, while others develop issues after only two or three years. High-quality boards use more robust materials and employ more refined lamination processes, resulting in greater impact resistance and aging resistance.
II. How to determine the severity of cracks in solar panels
When a board develops a crack, the first step isn't to think about how to repair it, but rather to assess its severity. Different types of cracks require completely different treatment methods.
To determine the severity of a crack, four main dimensions should be considered: the location of the crack, the shape of the crack, whether the crack is expanding, and whether it affects power generation.
Observe the location of the crack. If the crack is located on the outermost layer of the glass—the white front panel—it is relatively less serious because the main function of the outer glass is to protect the internal battery cells and circuitry. As long as the crack has not penetrated into the inner layer, the battery cells are still safe. If the crack has extended to the battery cells, or cracked all the way from the glass to the back panel, then it is more serious.
Observe the shape of the crack. Fine cracks, as thin as a hair, are usually just stress lines on the glass surface, which do not affect power generation and do not require special treatment. If the crack is a significant fissure, with a large width and long length, or even if obvious misalignment or delamination can be seen at the crack, then it needs to be taken seriously.
Observe whether the crack is expanding. The simplest way to judge is to mark both ends of the crack with a marker, and measure it with a ruler after a few days or weeks to see if the crack length has changed. If the crack continues to expand, it means the damage is continuously worsening and must be dealt with promptly. If the crack stabilizes and stops expanding, it can be observed further.
Check if it affects power generation. Once a solar panel develops a crack, the internal circuit connections may be affected, and the power generation efficiency will decrease to some extent. If you find that the power generation of a certain panel is significantly lower than that of other panels of the same model, it means that the crack in that panel may have already affected its power generation efficiency.
III. Detailed Explanation of Four Degrees of Injury
Based on the above criteria, I have divided the damage to solar panels into four levels, and I will discuss the manifestations and treatment methods for each level.
Level 1: Minor cosmetic damage
This type of damage mainly manifests as tiny scratches, abrasions, or extremely fine hairline cracks on the glass surface, typically no more than a few millimeters in length, located at the glass edge or corner, not in the cell area.
The impact of such damage on power generation efficiency is negligible, typically less than 5% or even insignificant. This is because the primary function of the outer glass layer is light transmission and protection; minor scratches and abrasions have very little effect on light transmittance. The cell area remains unaffected, and its power generation function is completely normal.
Solution: No replacement or repair is needed. Continue normal use. If you find it affects the appearance, you can wipe it with a special solar panel cleaner to remove surface dust and dirt, making the scratches less noticeable.
Level 2: Moderate crack damage
This type of damage manifests as noticeable cracks on the glass surface, ranging in length from a few centimeters to tens of centimeters. These cracks may branch or bend, but have not yet penetrated into the solar cell area. Looking at the back of the panel, there are no cracks or bulges. Gently pressing the panel surface reveals no obvious dents or looseness.
This type of damage has a certain impact on power generation efficiency, typically between 5% and 15%. This is because glass cracks can lead to localized stress concentration, affecting the working condition of the solar cells in that area; simultaneously, a small amount of moisture may seep in through the crack, affecting the light transmittance of the EVA film.
Handling method: Continuous observation is required. It is recommended to check the crack for expansion every three months. If the crack is stable and does not expand, it can continue to be used; if the crack continues to expand, or if a significant decrease in power generation is observed, it is necessary to consider replacing the board. A layer of transparent sealant tape can be applied to the crack to prevent further moisture penetration.
Level 3: Severe penetrating injury
This type of damage manifests as a through-crack in the glass, extending from the front to the back, or the glass shattering into multiple pieces without completely detaching. Obvious signs of moisture penetration are visible on the back of the panel, along with bulging or discoloration. The cell area is visibly damaged, with some cells showing obvious breaks or fractures.
The impact of such damage on power generation efficiency is typically between 15% and 50%, and in severe cases, it can cause the entire panel to stop generating electricity. Moreover, this damage poses safety hazards—broken pieces of glass may detach under wind force and fall, injuring people; moisture seeping into the interior may cause short circuits or fires.
Solution: Replacement is necessary. This type of damaged board cannot be used further and must not be operated while malfunctioning. When replacing, select a board of the same or compatible model, and it is best to have a professional installer perform the installation. Before replacement, disconnect the DC circuit containing this board to ensure safety.
Level 4: Complete damage
This type of damage manifests as solar panels being smashed into pieces or completely broken, or the frame deforming causing the panels to detach from the frame. This is relatively rare and usually occurs after extreme hailstorms or severe man-made damage.
The damage is obvious and must be addressed immediately. First, disconnect all circuits connected to the board to prevent short circuits and the risk of electric shock. Then, clean up any broken glass, being careful not to scratch the board. Finally, contact the installer or manufacturer to replace the board.
IV. How to prevent damage to solar panels
Having discussed damage management, let's talk about prevention. After all, solar panels are fixed assets, and nobody wants them to break down every now and then.
The most effective way to prevent physical impacts is to install protective netting or covers. In areas prone to hail, transparent protective netting can be installed above the boards, which does not affect lighting and blocks direct impact from hail. Some users also choose to install hail-proof glass in front of the boards, which increases costs but provides better protection.
Regular inspections are crucial. It's recommended to inspect the solar panels at least once a year, especially after exposure to extreme weather events such as hail, strong winds, or heavy rain. Inspections should include: checking for cracks, chips, or dents on the panel surface; ensuring the frame is intact; verifying the stability of the support structure; and confirming the junction box is properly sealed. Addressing minor issues promptly can prevent major problems.
Timely cleaning is essential. Dirt and dust on the surface of solar panels not only affect power generation efficiency but can also create localized hot spots under focused sunlight, accelerating panel aging. Regularly cleaning the panel surface and keeping the glass clean and transparent can reduce the risk of hot spots and stress concentration.
Pay attention to quality when purchasing. Solar panels of different qualities have vastly different impact resistance. Choose well-known brands and check if the product has passed IEC 61215 and IEC 61730 certifications. High-quality panels typically use high-transmittance tempered glass that has undergone rigorous hail resistance testing. "Cheap" products priced significantly below the market average may have compromised on materials, resulting in poorer impact resistance and aging resistance.
Conclusion
Whether a solar panel with cracks can still be used depends on the type and extent of the cracks.
Minor cosmetic damage—such as fine scratches on the surface glass—requires no treatment; continue using. Obvious cracks that haven't penetrated—require observation and monitoring to prevent them from widening. Penetrating cracks or damage affecting power generation—replacement is recommended; do not continue. Completely broken panels—must be replaced immediately with power off.
The principles for diagnosing and handling cracks in solar panels are simple: safety first, efficiency second, and economy third. If the cracks have already affected power generation efficiency or pose a safety hazard, don't continue to use them just because you're worried about the replacement cost. A solar panel with low power generation efficiency or safety hazards is like a time bomb hanging on the roof.
Hopefully, this article will help you accurately assess the extent of the damage to the board and make an appropriate decision. If you are still unsure, the simplest way is to take photos and send them to a professional installer or the manufacturer's customer service for evaluation.
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