Common Solar Panel Defects, Damage & Problems: A Homeowner's Guide

Solar panels are built to last 25 to 30 years, but solar panel damage, defects, and performance problems can appear long before a system reaches the end of its life. According to the 2025 Global Solar Report by Raptor Maps, equipment-driven underperformance has increased 214% since 2019, resulting in an estimated $10 billion in lost energy value worldwide in 2024 alone.

For homeowners, that translates directly to lower production, higher utility bills, and repair costs that could have been avoided. Common solar panel problems range from visible issues like discoloration and cracked panels to hidden faults like failed bypass diodes and delamination.

This guide covers the most common types of solar panel damage, what causes them, how professionals diagnose them, and what steps to take when something looks wrong.

Contact GreenLancer

How Solar Panel Problems Affect Your Energy Bill

Most homeowners notice solar panel problems through their utility bill before anything else. A production drop that looks small can add up fast, especially for systems that are 10 or more years old. NREL research shows the median solar panel degradation rate is about 0.5% per year, but panels with defects or physical damage can lose output much faster.

A 10% to 15% production dip may not seem urgent, but over 12 months it can mean hundreds of dollars in missed savings. Monitoring your system output through your inverter app gives you the earliest signal that something is wrong. The sooner a solar panel issue gets identified, the less expensive the fix tends to be.

Early Warning Signs Your Solar Panels Have a Problem

Some warning signs are visual. Others show up in your monitoring data first. Running a quick check on both fronts a few times a year can save a significant amount of money and prevent minor solar panel issues from becoming major ones.

Warning signs to watch for:

• Noticeable drop in monthly energy output or a higher-than-usual utility bill

• Monitoring app shows an unexpected production dip or zero output from a single panel

• Visible discoloration, browning, or yellowing on the panel surface

• Bubbling, blistering, or visible layer separation on the panel face

• Burn marks or scorch near the junction box

• Cracked or shattered glass on the panel face

• One panel producing significantly less than neighboring panels on the same string

Catching a faulty solar panel early almost always leads to a simpler fix. For a more detailed breakdown of when to call a technician, see these solar panel warning signs.

Solar Panel Parts Most Likely to Fail

Understanding how a solar panel is built helps explain why certain problems develop. Each component plays a specific role in converting sunlight into electricity, and each can become a source of solar panel defects when it degrades or fails. The Department of Energy's overview of how solar works and the solar photovoltaic cell basics page provide solid background if you want more depth on the technology.

Key components and common failure modes:

• Solar cells: Convert sunlight into electricity. Vulnerable to cracking, microfractures, and gradual UV degradation over time.

• Glass cover: Protects the cells from weather. Can crack under hail or impact; cloudiness from moisture intrusion reduces output.

• Encapsulation layer: Surrounds the cells for protection. Degraded encapsulant is a leading cause of discoloration and delamination.

• Backsheet: Rear insulation layer. Cracking is linked to moisture intrusion and safety concerns in some older panels.

• Junction box: Houses the bypass diodes and electrical terminals. Poor seals allow moisture in, leading to corrosion or electrical failure.

• Bypass diodes: Redirect current around shaded or damaged cells. A failed diode can cut that panel's output by up to 33%.

• Busbars and ribbons: Carry electrical current from cells. Corrosion or microcracks reduce output and contribute to hot spots.

• Edge seal: Prevents moisture and air from entering between layers. A degraded seal is often the starting point for delamination.

Most solar panel defects trace back to one of these components. Environmental stress, manufacturing quality, and installation practices all affect how long each part holds up.

Common Solar Panel Problems and Types of Damage

The most common solar panel problems fall into a handful of categories. Some are visible to the naked eye during a simple walkthrough of your property. Others require professional tools to confirm. Here is what to know about each one.

Solar Panel Discoloration

Solar panel discoloration typically appears as yellowing, browning, or purple staining across the panel surface. It is one of the more visible signs of aging or defects, and it often points to something happening inside the panel rather than just on the surface. UV radiation, encapsulant degradation, and moisture intrusion are the most frequent causes.

Discoloration does not always mean a panel has stopped producing electricity. It can reduce the amount of light reaching the solar cells, though, and gradually cut efficiency over time. If the staining is spreading or paired with an output drop in your monitoring app, a professional inspection is the right next step.

Solar Panel Delamination

Solar panel delamination happens when the internal layers of a module start to separate. The encapsulant, glass, and backsheet can pull apart due to heat cycling, moisture intrusion, or manufacturing defects. NREL research on field-deployed panels shows how moisture and voltage stress together accelerate this process, and it often appears as bubbling, cloudiness, or visible layer separation on the panel face.

Once moisture gets inside a delaminated panel, it drives corrosion and electrical shorts that worsen over time. Delamination typically cannot be repaired in the field. For panels with widespread delamination, decommissioning the affected panels is usually more practical than attempting repair.

Hot Spots on Solar Panels

A hot spot forms when one area of a panel overheats significantly more than the surrounding cells. This is usually caused by partial shading, soiling, a poor solder connection, or a failed bypass diode. Hot spots show up as bright regions on infrared thermal images taken during a professional inspection, and they are not always visible from the ground.

Left untreated, hot spots cause physical damage including cracked glass, burn marks, and cell burnout. In severe cases, particularly when a damaged backsheet allows heat to build near flammable materials, they can create a fire risk.

Safety note: If you see burn marks on a panel or near the junction box, or smell burning near your solar equipment, shut the system down and call a qualified solar technician right away. Do not attempt to open the junction box yourself.

Cracked Solar Panels and Microcracks

A cracked solar panel can range from shattered glass after a hailstorm to invisible microfractures inside the cells. Microcracks often happen during manufacturing, shipping, or installation and may not reduce output significantly at first. Over time, they spread and disrupt current flow across larger portions of the cell.

Visible glass cracks are easy to spot during a basic visual inspection. Microcracks require electroluminescence (EL) testing to detect, a process that passes a small current through the panel in the dark to reveal fractures in the cells. Even a cracked panel may still produce some power, but output will continue to decline without intervention.

Solar Panel Diode Failure

Each solar panel contains bypass diodes inside the junction box. Their job is to redirect current around shaded or damaged cells, preventing overheating and protecting the module. When a diode fails, it can no longer do that job, which leads to hot spots and a significant output drop.

According to Kiwa PVEL's module reliability testing methodology, a failed bypass diode can reduce that panel's output by up to 33%. Diode failure often shows up as a sudden production drop in your monitoring system, with localized heat visible on an IR scan. Replacing the faulty diode or the entire junction box is the standard repair.

Less Common Defects: PID and Snail Trails

Potential Induced Degradation (PID) is caused by voltage leakage between the solar cells and the panel frame. It is most common in hot, humid climates and causes gradual power loss that can resemble normal aging. IEC standard TS 62804-1 defines test methods for detecting PID susceptibility, and NREL's PV reliability research documents how PID affects real-world system performance over time. Snail trails are dark streak-like patterns on the panel surface caused by a chemical reaction inside the encapsulant, often triggered by moisture and microcracks. Both issues are worth flagging to a technician if output is declining alongside them.

Shading and Soiling

Shading and soiling are among the most common solar panel problems homeowners deal with, though they are not technically defects. A single shaded or dirty cell can reduce the output of the entire string it belongs to. New tree growth, nearby construction, and debris buildup from leaves or bird droppings are frequent culprits. Microinverters or power optimizers can reduce the impact of partial shading, and routine cleaning is one of the most effective preventive steps available.

Weather Damage to Solar Panels: Hail, Wind, Snow, and Falling Debris

Weather-related solar panel damage has become more common as severe weather events increase in frequency and intensity. Hailstorms, high winds, heavy snow loads, and falling debris each put different types of stress on a PV system. Knowing how each weather type affects your panels helps you assess the situation quickly after a storm.

Hail Damage

Hail is one of the most frequent causes of cracked solar panels in residential systems. Most modern panels are tested to withstand hailstones up to 25mm (about 1 inch) in diameter at roughly 50 mph under industry testing standards. Larger or faster hailstones can shatter the glass face, while smaller impacts may cause microcracks in the cells that are invisible on the surface but steadily reduce output over time.

After a major hailstorm, do a visual inspection of your panels from the ground. Look for cracked glass, visible impact marks, or shattered sections. If output dropped after the storm, contact your homeowner's insurer and a solar repair technician to assess the damage and determine whether a claim is warranted.

Wind and Snow Damage

High winds can loosen racking hardware, shift panels out of optimal angle, or in rare cases detach panels from the roof. Wind-driven debris including tree branches and roofing materials can cause impact damage to the glass or frame. After severe wind events, visually confirm that panels look level and that nothing appears shifted or loose.

Heavy snow loads put stress on panel frames and mounting systems, particularly on flat or low-pitch roofs. Most properly installed racking is engineered for local snow load requirements. Removing snow with improper tools is a common mistake, as scrapers and metal shovels can scratch or crack the glass. Use only tools designed specifically for solar panel snow removal.

Cosmetic vs. Production-Impacting Damage

Minor scratches, small frame dents, or surface discoloration from debris are often cosmetic and may affect insurance documentation more than system performance. The key question is always whether your production data shows a drop after the weather event.

If output stayed steady, visible damage is likely surface-level. If production dropped noticeably, a professional inspection is warranted to rule out microcracks or internal moisture intrusion. Review the solar panel warranty claims process before contacting your insurer to understand exactly what your coverage includes.

What Causes Solar Panel Damage

Solar panel damage comes from a mix of environmental exposure, manufacturing quality, and installation practices. Some causes are predictable and preventable. Others are simply the result of long-term outdoor exposure and the gradual wear that comes with it.

The most common causes of solar panel failure:

• UV radiation and prolonged heat exposure degrading encapsulant materials

• Severe weather: hail impacts, high winds, and heavy snow loads

• Manufacturing defects in the backsheet, encapsulant, or junction box

• Poor installation: improper grounding, inadequate racking, or loose wiring connections

• Moisture intrusion through a degraded edge seal or cracked backsheet

• Pest damage to wiring or junction box components from rodents or insects

• Extreme temperature cycling causing internal stress over many years of operation

The Department of Energy's homeowner solar guide notes that panels are designed for long-term outdoor durability, but quality varies significantly between manufacturers. Choosing panels with strong reliability testing results and installation by a NABCEP-certified installer reduces the risk of early solar panel failure significantly.

How Professionals Diagnose Solar Panel Problems

When a homeowner suspects a solar panel issue, a technician brings tools that go far beyond a visual inspection. Understanding what those tools do helps you ask better questions and make better decisions about repair or replacement.

Tools Most Homeowners Already Have Access To

System monitoring software from Enphase, SolarEdge, and SMA gives homeowners real-time production data at the panel or string level. A sudden output drop, an unexplained production gap, or repeated midday shutdowns are all worth investigating. Setting up automated alerts in your monitoring app is one of the best habits a solar homeowner can build. For more on what to look for, see solar system monitoring explained.

Professional Diagnostic Tools

When monitoring data points to a problem, technicians use specialized tools to find the root cause:

• Multimeters and clamp meters: Measure voltage and current at the panel or string level to confirm whether a panel is generating power.

• Handheld IR thermometers: Detect elevated surface temperatures that may indicate hot spots from diode failure or shading.

• Infrared (IR) thermography: Full thermal imaging of the array to identify overheating cells, junction box issues, and moisture-related damage.

• Electroluminescence (EL) testing: Passes a small current through the panel in the dark to reveal microcracks, inactive cells, and delamination that is not visible to the eye.

• IV curve tracing: Evaluates electrical performance under different load conditions to detect PID, wiring errors, or mismatched cells within a string.

A technician typically starts with monitoring data and a visual inspection before moving to advanced diagnostics. For a full breakdown of what a professional repair service includes, see the solar panel repair and warranty guide.

What to Do If You Have a Faulty Solar Panel

Finding a solar panel problem is stressful, but the path forward is straightforward. Acting methodically protects your warranty rights and gives a technician the best information to work with.

What to do when you spot a problem:

• Take photos of any visible damage and screenshot your monitoring app data showing the production drop

• Note when the problem started and whether it followed a weather event or a utility outage

• Locate your original installation paperwork and manufacturer warranty documents

• Review your warranty: product warranties cover material defects, performance warranties cover output degradation

• If the system is under warranty, contact the manufacturer's warranty department directly

• If your original installer has closed, a national solar repair network can handle warranty coordination and repairs

Manufacturer warranties cover defects in materials and workmanship and typically run 10 to 25 years depending on the brand. Performance warranties generally guarantee 80% or more of original output capacity after 25 years. Both warranties remain valid regardless of whether the original installer is still in business. For the full breakdown of how to file a claim, see the solar panel warranty claims guide.

Which Solar Panels Are More Reliable

Choosing a high-quality module upfront significantly reduces the likelihood of early defects. The Kiwa PVEL 2025 PV Module Reliability Scorecard is the most widely referenced independent testing resource in the industry. Panels that earn Top Performer status in thermal cycling, humidity-freeze, and mechanical stress testing are more resistant to delamination, PID, and diode failure over the life of the system.

The GreenLancer breakdown of the PVEL scorecard translates those results into practical guidance for homeowners. Looking for panels with Top Performer status across multiple test categories is a solid starting point. Strong manufacturer warranties, consistent reliability records, and NABCEP-certified installation all contribute to long-term system performance.

Frequently Asked Questions About Solar Panel Damage and Defects

What are the most common solar panel problems homeowners face?

The most common issues are discoloration, delamination, hot spots, cracked panels, and diode failure. Shading from tree growth and surface soiling from debris are also frequent causes of reduced output. Most of these problems are detectable through monitoring software combined with routine visual inspections.

How do I know if my solar panels are damaged?

The clearest indicators are a production drop in your monitoring app, visible discoloration or staining on the panel surface, cracked or shattered glass, burn marks near the junction box, and bubbling or blistering on the panel face. If you notice any of these, a professional inspection is the right next step.

What causes solar panels to stop working?

Solar panels rarely fail all at once. More often, defects like diode failure, delamination, or microcracks reduce output gradually over time. Severe weather damage, moisture intrusion, and inverter problems can cause more sudden production drops. In older systems, general degradation across the array may be the primary contributing factor.

What does solar panel discoloration mean?

Discoloration most often signals UV degradation of the encapsulant, moisture intrusion, or chemical breakdown inside the panel layers. Yellow or brown staining is the most common presentation, while purple or dark spots can indicate more serious cell-level damage. It does not necessarily mean the panel has failed, but it warrants monitoring and potentially a professional inspection.

Can solar panel delamination be repaired?

In most cases, no. Once the internal layers have separated and moisture has entered, the panel's integrity is compromised and replacement is typically more practical than repair. If the panel is under a product warranty, the manufacturer may cover the cost. For severely delaminated or aging panels, decommissioning the affected panels is often the most cost-effective path forward.

Are defective solar panels covered under warranty?

Yes, in most cases. Product warranties cover material and workmanship defects and typically run 10 to 25 years. Performance warranties cover output degradation and generally guarantee at least 80% of original output after 25 years. Both types of warranty are held by the manufacturer rather than the installer, and they remain valid even if your original installer has closed.

What is a solar panel hot spot and is it dangerous?

A hot spot is a localized area of a panel that overheats significantly more than surrounding cells, typically caused by partial shading, soiling, poor solder connections, or a failed bypass diode. In severe cases, hot spots can cause cracked glass, burn marks, and a fire risk, particularly if the backsheet is compromised. If you see scorch marks or smell burning near your solar equipment, shut the system down and call a technician immediately.

Can a cracked solar panel still work?

Yes, a cracked solar panel can still produce electricity, but output will be reduced and will likely continue to decline. Microcracks may cause only a small initial loss. Shattered glass or larger fractures can expose internal components to moisture, which accelerates further damage. A cracked panel should be assessed by a technician to determine whether repair or replacement is the better option.

How long do solar panels last before they develop problems?

Most quality panels last 25 to 30 years with gradual performance decline. According to NREL research, the median degradation rate is about 0.5% per year under normal conditions. Defects and physical damage can appear earlier, particularly after severe weather or in systems with lower-quality components. Systems that are 10 to 15 years old and have never had a professional inspection are good candidates for a preventive check.

What should I do if my original solar installer went out of business?

Your manufacturer warranties are still valid. Component warranties are held by the panel, inverter, and battery manufacturers, so the closure of a local installer does not affect your coverage. A national solar repair network like GreenLancer can diagnose your system, coordinate warranty claims directly with manufacturers, and repair virtually any brand of equipment. See the full solar panel repair and warranty guide for next steps.