Common Solar Panel Defects: Solar Panel Discoloration & Delamination

If your solar energy system isn’t producing as much power as it used to, equipment-related issues may be the cause. According to the 2025 Global Solar Report by Raptor Maps, underperformance linked to hardware problems has increased by 214% since 2019. This translated to an estimated $10 billion in lost energy value worldwide in 2024, and can cost homeowners hundreds of dollars each year in reduced savings.

Common solar panel defects, such as discoloration, delamination, and solar panel diode failure, often become more likely as systems age. These issues reduce overall efficiency and may lead to more expensive repairs if not addressed promptly.

Weather-related solar panel damage is also on the rise. Heatwaves, hailstorms, and high winds are putting extra stress on PV modules, making solar panel defects more common than in past years.

While not every issue is preventable, regular solar system monitoring and inspections can help minimize its impact. Watch for solar panel discoloration, drops in output, or visible damage. Catching problems early helps protect your investment and keeps your solar system operating at peak performance.

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 & How They Relate to Common Defects

Understanding the components of a solar panel helps diagnose performance issues and identify common solar panel defects. Problems such as solar panel discoloration, solar panel delamination, and solar panel diode failure often trace back to degradation in one or more of these parts. Below is an overview of the essential components and how each one can contribute to solar panel damage over time.

• Solar Cells: Photovoltaic (PV) cells are the heart of any panel, converting sunlight into direct current (DC) electricity. Over time, solar cells can crack or become discolored, especially due to UV exposure or heat stress, both leading causes of solar panel defects and power loss.

• Frame: The rigid aluminum frame supports the panel and helps protect it against mechanical damage. Bent or corroded frames, often caused by hail or salt exposure, can result in water ingress and long-term solar panel damage.

• Glass Cover: This tempered glass layer protects the PV cells while allowing sunlight through. Cracks or cloudiness in the glass can reduce energy output and may lead to visible solar panel discoloration, especially when combined with internal moisture intrusion.

• Encapsulation Layer: This clear protective layer surrounds the solar cells to guard against humidity and thermal cycling. Degraded or low-quality encapsulation can cause solar panel delamination, where the protective layers separate and compromise panel performance.

• 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: The junction box houses the electrical terminals and bypass diodes. If the box is poorly sealed, water or heat can damage internal components, potentially leading to solar panel diode failure or electrical shorts.

• 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.

• Edge Seal: The edge seal runs around the perimeter of the panel to keep moisture, dust, and air from entering between the glass and the encapsulant. If the edge seal degrades, it can lead to solar panel delamination, discoloration, or corrosion of internal components. This is often a hidden failure that worsens over time.

• Heat Sink or Thermal Pad (in some advanced panels): Some premium modules include thermal pads or heat-dissipating features to reduce the temperature of sensitive components. Excessive heat accelerates many solar panel defects, including diode failure, delamination, and discoloration. Efficient heat management can extend lifespan.

  
  

How To Spot Common Solar Panel Damage & Defects

Solar panel damage can seriously reduce your system’s performance and shorten its lifespan. Fortunately, regular visual inspections and monitoring can help you identify common solar panel defects early, before they lead to expensive repairs or replacements.

Identifying Drops in Solar Energy Output

A noticeable drop in energy production, especially when weather conditions remain stable, often signals underlying issues. These can include solar panel diode failure, delamination, or solar cell degradation. Comparing current system output to expected performance is one of the best ways to detect hidden equipment problems.

Recognizing Solar Panel Discoloration

Solar panel discoloration is one of the most visible signs of potential damage. This typically appears as brown, yellow, or purple stains on the panel surface.

Discoloration is often caused by UV degradation, heat buildup, or problems with the encapsulant layer. Over time, it can interfere with light absorption, contributing to lower energy output and other solar panel defects. If discoloration spreads or worsens, it may be time to schedule a professional inspection.

Solar Panel Diode Failure and Hotspots

Solar panel diode failure isn’t always easy to spot, but it can lead to serious consequences. Bypass diodes reroute current around shaded or damaged cells, protecting the module.

When a diode fails, hotspots can form, creating local overheating, visible burn marks, or even fire risks. Hotspots may also lead to solar panel discoloration or cracked glass. Infrared imaging and electrical testing are useful tools for spotting diode issues before they escalate.

Signs of Solar Panel Delamination

Solar panel delamination occurs when the layers within a module start to separate, often between the glass, encapsulant, and backsheet. This defect can allow moisture and air into the panel, leading to corrosion, diode failure, or short circuits.

Early signs of delamination include cloudiness, bubbling, or blistering on the panel surface. Delaminated panels are more prone to solar panel damage and reduced lifespan, especially in systems exposed to extreme weather.

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 Damage & Defects

Many common solar panel defects result from manufacturing flaws or long-term exposure to environmental stress. Problems like poor solder joints, weak glass or frame materials, faulty junction boxes, busbar corrosion, and low-grade encapsulants can all contribute to gradual solar panel damage and reduced performance.

These defects may not lead to immediate failure, but they often shorten the system’s lifespan and reduce energy output over time. Visual indicators—such as solar panel discoloration, delamination, or signs of overheating at the junction box can point to underlying issues like moisture intrusion or solar panel diode failure.

Regular inspections and solar monitoring are key to detecting problems early. Catching these solar panel defects before they escalate helps prevent performance losses, protects warranties, and reduces long-term repair costs.

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.
  

Diagnostics Tools for Identifying Solar Panel Defects

Detecting common solar panel defects like discoloration, delamination, and solar panel diode failure often requires more than a visual inspection. Many issues, such as microcracks, potential induced degradation (PID), or internal electrical faults, can remain hidden without the right diagnostic tools. Solar professionals rely on a range of technologies to pinpoint the root cause of solar panel damage and underperformance.

Common Diagnostic Tools Most Solar Installers Use

Multimeters and Clamp Meters

These essential electrical tools are used to measure voltage and current at the panel or string level. Multimeters confirm whether a panel is generating power, while clamp meters measure the current flowing through conductors. If a panel shows low or zero voltage, this may signal internal issues such as solar panel diode failure, disconnected wires, or short circuits. These tools are crucial for everyday troubleshooting and on-site diagnostics.

System Monitoring Software

Module-level monitoring from inverters like Enphase, SolarEdge, and SMA helps flag underperforming panels or strings. The data can reveal patterns consistent with solar panel damage, such as sudden drops in output, irregular shading, or signs of diode failure. Monitoring can also detect emerging problems like solar panel discoloration or delamination, which may show up as gradual efficiency loss across specific modules.

Handheld IR Thermometers or Entry-Level Thermal Cameras

Some installers use affordable infrared tools to identify hotspots caused by solar panel diode failure, cracked cells, shading, or loose electrical connections. While not as detailed as professional-grade IR cameras, these tools can detect elevated surface temperatures—an early indicator of hidden solar panel defects or damage.

Advanced Diagnostic Tools Used by Some Installers or Specialists

Electroluminescence (EL) Testing

EL testing uses a specialized camera to capture near-infrared light emitted by solar cells when voltage is applied in the dark. This method reveals otherwise invisible microcracks, solar panel delamination, broken busbars, and encapsulant defects.

• Best for: Identifying subtle structural damage resulting from manufacturing flaws, transportation stress, or poor installation.

• Common defects detected: Microcracks, snail trails, inactive cells, and cell fractures.

Infrared (IR) Thermography

IR thermography uses thermal imaging to detect temperature differences across a panel’s surface. Hotspots are clear indicators of internal faults, typically linked to solar panel diode failure, corrosion, or shading. IR scans are especially useful for large arrays.

• Best for: Diagnosing overheating that can cause solar panel discoloration, cracked glass, or fire risk.

• Common defects detected: Diode failure, loose connections, moisture damage, and PID.

IV Curve Tracing

IV (current-voltage) curve tracers assess a panel’s electrical performance under different loads. Deviations from the expected curve can reveal a range of issues, including bypass diode failure, PID, or mismatched modules in an array.

• Best for: Verifying system performance and isolating causes of underproduction.

• Common defects detected: PID, low output, wiring errors, soiling, shading issues.

  
  

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 Damage & 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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