Common Solar Panel Defects: Solar Panel Discoloration & Delamination

If your solar energy system isn’t performing the way it used to, you’re not alone. According to Raptor Maps' 2025 Global Solar Report, equipment-related underperformance has surged by 214% since 2019, leading to an estimated $10 billion in lost revenue globally in 2024. This can add up to hundreds of dollars in lost energy bill savings per year.

So what’s behind the rise in solar panel issues? As solar systems age, they become more prone to common solar panel defects like discoloration, delamination, and solar panel diode failure. These problems reduce your system’s energy output and can increase repair costs over time. On top of that, more frequent extreme weather, like heatwaves, hail, and heavy storms, is putting additional stress on solar equipment, leading to more cases of solar panel damage.

While many of these issues can’t be avoided entirely, you can reduce their impact with regular system checks and monitoring. Watch for signs of solar panel discoloration or drops in energy production, and address concerns early before they become costly. Staying informed and proactive helps protect your solar investment and keeps your system working efficiently for years to come.

If your solar panels are underperforming, GreenLancer can help with expert repair or replacement services to restore your system’s energy output. Don’t let common solar panel defects reduce your savings—get your system back on track with support from our nationwide network.

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Components of a Solar Panel

Understanding the key components of a solar panel is essential for identifying and diagnosing common solar panel defects. Issues like solar panel discoloration, delamination, or solar panel diode failure often originate from damage or degradation to these specific parts over time. Here's a breakdown of the major components and their functions:

• Solar Cells: These photovoltaic (PV) cells are the core of the panel, responsible for converting sunlight into direct current (DC) electricity. Cracked or discolored cells are a frequent source of solar panel damage.

• Frame: The aluminum frame gives structural support and protects internal components. Frame warping or corrosion can contribute to solar panel defects, especially in harsh environments.

• Glass Cover: Made of tempered glass, this cover shields the solar cells from weather while allowing maximum sunlight transmission. If cracked or clouded, it can reduce performance and lead to solar panel discoloration.

• Encapsulation Material: This layer surrounds the solar cells to protect against moisture and environmental stress. Poor encapsulation can lead to solar panel delamination, where layers peel apart and reduce output.

• Solar Panel Backsheet: Located on the rear of the panel, the backsheet provides electrical insulation and additional protection. Backsheet cracking is a known issue tied to solar panel defects and safety concerns.

• Junction Box with Diodes: This is where the panel's wiring connects to the rest of the system. It typically houses bypass diodes, which prevent power loss due to shaded or malfunctioning cells.

• Solar Panel Diodes: Bypass diodes inside the junction box prevent reverse current and overheating. Diode burnout or failure—known as solar panel diode failure—can compromise entire strings of modules.

• Busbars and Ribbons: These thin, conductive strips collect and carry the electrical current from the cells. Corrosion or microcracks can lead to inconsistent output or damage to the solar panel.

• Anti-reflective Coating: Applied to the front glass, this coating minimizes sunlight reflection and improves absorption. Degradation of this coating may contribute to solar panel discoloration and reduced efficiency over time.

  
  

How To Spot Common Solar Panel Defects

Solar panel damage can severely impact system efficiency and shorten the lifespan of a PV installation. However, regular performance monitoring and visual inspections can help identify common solar panel defects early.

A significant drop in power output, especially when weather conditions haven’t changed, can indicate underlying issues like solar panel diode failure, delamination, or cell-level degradation. Comparing current energy production with expected system output is a key method for pinpointing performance anomalies due to equipment faults.

Recognizing Solar Panel Discoloration

Solar panel discoloration is one of the most visible warning signs of trouble. This typically appears as brown, yellow, or purplish tints on the module surface. Discoloration often results from heat stress, UV exposure, or encapsulant degradation—all of which can interfere with solar energy absorption and contribute to solar panel defects. If the affected area is widespread or worsening over time, it’s important to investigate further to determine whether performance is being compromised.

Solar Panel Diode Failure and Hotspots

Solar panel diode failure is a less visible but equally critical issue. Bypass diodes are designed to protect panels by rerouting current around shaded or damaged cells. When these diodes fail, it can lead to hotspots—localized overheating that causes visible solar panel discoloration, cracks, or burn marks. These hotspots not only reduce output but can also cause long-term solar panel damage or fire risk if left unaddressed. Infrared inspections or diode testing can help detect faulty bypass components before they escalate.

Solar Panel Delamination

Solar panel delamination is a serious defect that occurs when the layers of a solar module begin to separate, typically between the glass, encapsulant, and backsheet. This separation can allow moisture, air, and other contaminants to enter the panel, increasing the risk of corrosion, solar panel diode failure, and electrical shorts. Delamination often starts as subtle bubbling or cloudiness but can lead to visible blistering or peeling on the panel surface.

Delamination significantly compromises the durability and long-term performance of a PV system. It can also trigger solar panel discoloration and accelerate cell degradation, reducing overall efficiency. Most delamination issues stem from poor manufacturing, extreme thermal cycling, or long-term UV exposure. Once detected, affected panels may need to be removed or replaced to prevent further solar panel damage across the array.

Other Common Solar Panel Problems

Routine inspections often uncover common solar panel defects such as cracks, chips, or dust accumulation, all of which can reduce sunlight absorption and lead to decreased output. Surface damage is a frequent cause of solar panel performance issues, especially in aging systems or those exposed to harsh environments.

Electrical faults are another concern—loose wiring, corroded terminals, and poor grounding can result in power loss or safety hazards. In some cases, solar panel diode failure or a malfunctioning inverter may be the root cause of underperformance. Identifying these issues early helps prevent further solar panel damage, extend system life, and maintain optimal energy production.

Identifying Common Solar Panel Problems & Defects

Many common solar panel defects stem from equipment anomalies introduced during manufacturing or accelerated by environmental stress over time. Issues such as poor soldering, inadequate lamination, faulty cell design, weak glass or frame construction, junction box defects, busbar corrosion, and low-quality encapsulation can all lead to reduced solar panel performance. These problems may not cause immediate failure, but can gradually degrade output and shorten the lifespan of your system.

Fortunately, many of these issues are detectable through regular maintenance, solar performance monitoring, and visual inspections. Visible signs—like solar panel discoloration, delamination, or burned junction boxes—often indicate deeper problems such as moisture ingress or solar panel diode failure. Identifying and addressing solar panel damage early can help prevent energy losses, reduce maintenance costs, and protect system warranties.

Common Solar Panel Defects & Discoloration	Causes of Solar Panel Problems
Snail Trails	These dark, snail-like streaks are a form of solar panel discoloration caused by a chemical reaction between moisture, oxygen, and silver paste in the cell grid. They are usually a sign of microcracks or moisture penetration in the encapsulation layer and can lead to reduced output over time.
Hotspots	Hotspots form when parts of a panel overheat due to shading, soiling, or solar panel diode failure. These localized high-temperature zones not only reduce energy production but can also cause solar panel damage or even pose fire risks if left unaddressed.
Shading & Shadowing	Partial shading on even one cell can cause disproportionate performance losses across the panel due to how PV modules are wired. Long-term shading can contribute to common solar panel defects and increase the risk of hotspots.
Microcracks	These tiny fractures in the silicon cells often develop during transport, installation, or due to thermal expansion and contraction. Microcracks may be invisible to the naked eye but can expand over time, reducing current flow and leading to larger solar panel defects like delamination or cell failure.
Solar Panel Delamination	Delamination occurs when layers of the panel—usually the encapsulant and backsheet—begin to separate. This separation allows moisture to enter, leading to solar panel discoloration, corrosion, and decreased efficiency. It is one of the more serious solar panel damage issues requiring prompt attention.
Potential Induced Degradation	PID is a type of performance degradation caused by voltage stress between the solar cells and other module components, like the frame or glass. This phenomenon can significantly reduce energy output and is more common in humid or high-voltage environments.
Solar Panel Diode Failure	When bypass diodes short-circuit or fail, it disrupts current flow across the panel and can result in both hotspots and lower overall efficiency. Solar panel diode failure is a key contributor to long-term solar panel defects and requires electrical testing to diagnose accurately.

Solar Panel Snail Trails

Snail trails are a visible form of solar panel discoloration that appear as thin, dark streaks or patterns on the surface of a module. This solar panel defect is caused by a chemical reaction within the encapsulation material, often triggered by the presence of moisture and oxygen. Over time, these reactions can form conductive pathways that degrade the panel's electrical performance, especially when combined with microcracks or internal corrosion.

To identify snail trails, inspect the surface of your panels in direct sunlight, when these markings are easiest to spot. While snail trails don't always cause a significant drop in output, they can signal deeper solar panel defects and should be monitored. If the panels are under warranty, contact the manufacturer to determine whether a replacement is warranted based on performance degradation.

Hotspots on Solar Panels

Hotspots occur when certain cells within a solar module overheat due to localized shading, soiling, poor solder connections, or solar panel diode failure. This is a serious issue, as overheating can lead to permanent solar panel damage—including cell burn-through, cracked glass, and decreased system performance.

Thermal imaging during full sunlight is the most effective way to identify hotspots; they appear as bright or glowing regions compared to the rest of the panel. To prevent hotspot formation, ensure regular cleaning and maintenance of the array. If hotspots are linked to faulty diodes or manufacturing issues, affected panels may need to be replaced to avoid further damage.

Shading And Shadowing

While not technically a solar panel defect, shading is a common solar panel problem that can dramatically reduce output—even if just one cell is partially shaded. Because cells are wired in series, a single shaded area can impact the performance of the entire module or string.

Inspect the array throughout the day, especially during morning and late afternoon, when shadows shift the most. Nearby trees, roof features, or new construction are common culprits. Encourage homeowners or facility managers to watch for new obstructions. Installing microinverters or power optimizers can mitigate the effects of shading across an array, especially in systems with variable light exposure.

Solar Panel Microcracks

Microcracks—also called microfractures—are one of the most overlooked common solar panel defects. These tiny, often invisible cracks occur in the silicon cells due to handling during shipping, installation stress, or thermal cycling over time. Left unchecked, microcracks can spread, causing solar panel damage and long-term power loss.

Visual inspection under proper lighting may reveal faint lines, but electroluminescence (EL) testing is the gold standard for detecting microcracks. If microcracks are found and panel output is still within acceptable limits, no action may be needed. However, significant cracking that affects energy production may warrant a panel replacement or a warranty claim.

Solar Panel Delamination

Solar panel delamination occurs when internal layers of the module, particularly between the glass, encapsulant, and backsheet, begin to separate. This separation allows moisture and air to infiltrate the panel, leading to busbar corrosion, solar panel discoloration, and eventual electrical failure.

To identify delamination, perform a close visual inspection for bubbling, blistering, or layer separation. EL imaging can also detect underlying defects not visible to the eye. Severe solar panel delamination not only reduces efficiency but can pose safety risks due to the potential for electrical shock. If the panel is under warranty, contact the manufacturer for replacement options. For aging systems with widespread delamination, decommissioning may be more cost-effective than replacing individual panels.

Potential Induced Degradation (PID)

PID is a well-documented and common solar panel defect that can significantly reduce the performance and reliability of a PV system. PID occurs when there’s a high-voltage potential difference between the photovoltaic cells and the frame, glass, or mounting structure of the panel. This mismatch allows leakage currents to flow, which can degrade the solar cells and cause a drop in energy production. PID is particularly problematic in hot and humid environments and is a leading cause of long-term solar panel damage.

To detect PID, system owners and operators should routinely monitor output levels and compare actual performance against modeled expectations. A sudden or gradual decline in production—especially under high temperature and humidity conditions—can signal the onset of PID. If left unaddressed, PID can cause significant losses in system output and contribute to other solar panel defects like solar panel discoloration and premature aging of modules.

Addressing PID involves both preventive and corrective strategies. PID reversal devices can sometimes restore lost performance in affected panels. Proper system grounding and insulation are key to minimizing voltage leakage and reducing the risk of PID. In addition, using string inverters with transformer isolation or module-level power electronics (MLPE) like optimizers can provide better voltage control and help prevent this type of solar panel damage from developing.

Solar Panel Diode Failure

Solar panel diode failure is a critical and often overlooked issue that can have a major impact on system performance. Bypass diodes, built into the panel's junction box, are designed to redirect current around shaded or underperforming cells to prevent energy losses and protect the system from hotspots. When these diodes fail—typically by short-circuiting or becoming open—they can result in severe efficiency drops, sometimes causing more than a 33% reduction in power output from the affected panel. This failure can also lead to overheating and visible solar panel discoloration, ultimately shortening the panel’s lifespan.

According to recent PVEL PV Module Reliability Scorecards, solar panel diode failure remains one of the top contributors to performance degradation across multiple module brands. To catch these issues early, solar professionals should regularly review system monitoring data for unusual production losses or thermal imbalances. Visual inspections can also reveal common solar panel defects like burned junction boxes or localized hotspots, clear indicators of diode issues.

The only reliable fix for solar panel diode failure is replacing the faulty diode, which often requires accessing or replacing the entire junction box. Early intervention prevents cascading failures and reduces the likelihood of long-term solar panel damage or safety hazards. Regular maintenance, paired with performance analytics, helps ensure optimal energy yield and supports the long-term reliability of the solar PV system.

What are some of the most common solar panel defects?

Several common solar panel defects can significantly reduce system performance and reliability over time. One of the most frequent issues is microcracks—tiny fractures in the photovoltaic cells that often occur during manufacturing, handling, or transportation. These cracks can spread over time, disrupt current flow, and contribute to uneven degradation or solar panel discoloration.

Another major issue is solar panel delamination, where the layers of the panel begin to separate due to poor lamination or environmental exposure. Delamination allows moisture to enter the module, increasing the risk of solar panel damage, corrosion, and long-term output decline.

Hotspots are also a critical concern. These occur when parts of a panel overheat due to shading, cell mismatch, or manufacturing flaws. Hotspots not only reduce efficiency but can also lead to physical damage such as cracked glass or burn marks. Finally, solar panel diode failure is another important defect to watch for. When bypass diodes malfunction, they can prevent current from properly bypassing shaded or damaged cells, leading to significant power losses and an increased risk of hotspots.

Staying aware of these solar panel defects and addressing them through proactive maintenance and monitoring is essential for maintaining long-term solar system performance.

What causes solar panel discoloration?

Solar panel discoloration is a visible and often early indicator of solar panel defects or environmental degradation. It typically presents as yellowing, browning, or uneven shading across the surface of a PV module and can be detected during routine visual inspections. While some discoloration may be cosmetic, in many cases, it signals underlying issues that can contribute to solar panel damage and reduced energy output. Below are the most common causes of solar panel discoloration:

• Exposure to UV Radiation: Prolonged exposure to ultraviolet (UV) rays can degrade encapsulant materials and polymers within the panel, especially in lower-quality modules. This can lead to solar panel discoloration, such as yellowing or browning, and often signals early-stage solar panel delamination or chemical breakdown inside the module layers.

• Environmental Pollution: Dust, pollen, industrial emissions, and airborne pollutants can accumulate on panel surfaces over time. These substances form a layer that not only causes visual discoloration but also blocks sunlight from reaching the solar cells, contributing to long-term solar panel defects and decreased output if not regularly cleaned.

• Moisture and Humidity: In high-humidity environments or regions with frequent rainfall and fog, moisture can seep into compromised panel edges or backsheets. This encourages the growth of mold, lichen, or algae, leading to both solar panel discoloration and potential solar panel damage due to electrical isolation breakdown or corrosion.

• Improper Maintenance: Lack of cleaning and preventive maintenance can allow debris and biological growth to settle on panels for extended periods. This not only causes uneven discoloration but increases the risk of hotspots and degraded system performance—especially in systems with solar panel diode failure or poorly ventilated mounting designs.

• Material Degradation: Over time, the materials used in panel construction—particularly the encapsulants—can chemically degrade under exposure to heat, UV radiation, and environmental stress. This often results in visible solar panel discoloration and may accompany solar panel delamination, reducing transparency and interfering with light transmission.
  

Selecting modules to avoid common solar panel problems

Choosing the right solar panels is one of the best ways to avoid common solar panel defects like Potential Induced Degradation (PID), solar panel delamination, and diode failure. The PVEL 2024 scorecard is a helpful resource for homeowners, as it ranks PV modules based on extensive reliability and performance testing. Panels that perform well in thermal cycling, humidity-freeze, and mechanical stress tests are more resistant to solar panel damage and long-term performance loss.

By selecting high-quality modules from manufacturers with strong PVEL test results, you reduce the chances of running into common solar panel problems like solar panel discoloration or electrical failure. Investing in proven, durable equipment helps ensure your system delivers dependable energy output and savings for years to come.

FAQs on Common Solar Panel Problems & Defects

Get answers to common questions about solar panel discoloration, delamination, diode failure, and more.

Do defects cause solar panel discoloration?

Solar panel discoloration is typically the result of long-term exposure to the elements, such as sunlight, rain, and dust. Also, an uncontrolled chemical reaction between the lamination materials, such as EVA (ethylene-vinyl acetate), and the oxygen in the environment can contribute to discoloration. However, although solar panel discoloration may affect the aesthetic appearance of the panels, it does not generally impact their solar energy output or efficiency.

In some cases, severe discoloration could potentially indicate damage, although the presence of discoloration does not necessarily imply a solar panel defect. The most common defects in solar panels include issues such as hot spots, snail trails, and imperfections in the materials. These defects can impact the performance, longevity, and safety of the solar panels.

What causes solar panel diode failure?

Solar panel diode failure may occur due to overheating in high temperatures, excess voltage from mismatched panels, reverse polarity from wiring issues, manufacturing defects, lightning strikes, moisture issues causing corrosion, and natural aging. These factors can compromise the integrity of the solar panel diode, decreasing solar system output. Regular monitoring and maintenance are essential to detect and address potential issues quickly.

How can I prevent solar panel diode failure?

Preventing solar panel diode failure starts with proper installation and quality components. Using surge protection devices, regularly inspecting for solar panel damage, and keeping panels clean can help reduce stress on bypass diodes. Minimizing shading through thoughtful panel placement also decreases the risk of hotspots that can trigger diode issues.

Effective sealing and temperature management are key to avoiding moisture ingress, which can lead to long-term solar panel defects like diode failure and discoloration. Choosing PV modules from reputable manufacturers known for quality and durability further protects against common solar panel problems, helping ensure the longevity and performance of your system.

How can I detect common solar panel problems?

Regular solar system monitoring and inspection are essential to detect common solar panel problems or defects. Visually inspect panels for physical damage, use monitoring software to track renewable energy production, and check inverter readings for abnormalities.

Solar technicians can analyze shading patterns and conduct electrical tests to identify wiring issues. Early detection and intervention of solar panel damage and issues help maintain optimal solar system performance.

Solar Panel Defects Are Rare But Possible

Your solar energy system should consistently deliver reliable energy and long-term savings. If you notice a drop in performance, there may be an underlying issue, sometimes caused by common solar panel defects such as solar panel discoloration, delamination, or diode failure, which may be covered under your manufacturer’s warranty. Understanding these issues can help you recognize signs of solar panel damage early and work with a trusted provider to restore performance.

Effective system design is key to preventing many common solar panel problems, including Potential Induced Degradation (PID) and solar panel diode failure. Features like proper grounding, adequate airflow, and high-quality materials help reduce overheating and electrical stress, improving durability and extending the lifespan of your solar installation.

GreenLancer offers nationwide solar repair services to help diagnose and fix issues like solar panel defects, damage, or underperformance. Get your system back on track with fast, reliable support from our network of solar professionals.

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