PV System Faults and Causes

PV system faults can reduce production or create safety risks in modules, wiring, inverters and other equipment. Aerial thermography helps locate abnormal temperature patterns, but it neither repairs faults nor proves every root cause. Combine thermal and visible evidence with operating data and qualified field diagnosis.

Cracks can arise during manufacturing, transport, installation or service. Some affect current flow and create a thermal pattern, while others are not visible in an aerial thermal survey. Use visible inspection for glass damage and targeted electrical or electroluminescence testing where cell cracking is suspected. The IEA PVPS failure review discusses these complementary diagnostic methods.

Inverters convert the DC electricity produced by PV modules into AC electricity. Shutdowns may reflect internal faults, overheating, grid conditions or protective operation. Record fault codes and operating conditions before selecting the diagnostic procedure.

Shadowing refers to the condition where one or more PV panels are in shadow. Shading reduces panel efficiency, which leads to a reduction in energy production. Panel layout can be optimized by detecting shadowing areas with aerial thermography.

Module temperature depends on irradiance, wind, mounting and electrical operation. Restricted ventilation can contribute to higher temperatures, but a warm panel alone does not prove a cooling fault. Compare similar modules under comparable conditions before recommending changes.

Soiling can reduce the light reaching cells and may create visible or thermal patterns. Review thermal findings alongside visible images and output data before specifying cleaning. Cleaning frequency should reflect site conditions and manufacturer instructions rather than an assumed universal schedule.

MapperX analyzes inspection imagery to help organize suspected PV anomalies for follow-up. The operational value comes from locating the issue, verifying the cause and completing appropriate maintenance; a survey alone does not guarantee higher production or lower costs.

• Cell Faults

Cell-related thermal anomalies appear as localized areas where the temperature is higher than the rest of the PV panel. Overheating alone does not confirm a cell fault; the cause requires operating context and follow-up checks.

• Multi Cell Faults

An anomaly that occurs when more than one cell in the panel overheats. It is indicated in the thermal data by a few spots where the temperature has a higher intensity than the rest of the panel.

• Diode Fault

A bypass diode provides an alternate current path around a cell substring under suitable electrical conditions. Bypass operation is not itself proof of a failed diode. A substring-shaped thermal pattern may justify a diode or circuit investigation, but the affected area depends on the module’s electrical design.

• Multi Diode Fault

When several substrings are bypassed or affected by diode problems, more than one region of a module may show an abnormal pattern. The affected area is determined by the module circuit and operating state, not a universal fraction. Check the circuit design before attributing the pattern to multiple failed diodes.

• Hotspot Fault

A hotspot is a localized area of elevated temperature. Reverse-biased or damaged cells and resistive connections can dissipate electrical power as heat. A thermal hotspot is an observation; shading, soiling, cell damage and connection faults require different verification and remedies.

• Junction Box Fault

A module junction box houses electrical connections and commonly bypass diodes, linking the module circuit to its external leads. Abnormal heating can warrant inspection of connections or diodes, but the cause must be verified using safe, manufacturer-approved procedures.

• Module Fault

A whole-module temperature contrast can be associated with a different electrical operating state, disconnection or a module problem. It is not proof that the module has completely failed. Check the string circuit and operating data before classifying the cause.

• Shadowing Faults

Shading reduces the light available for electricity generation and can create mismatch or bypass-diode operation. Some conditions can lead to heating, but shading does not always produce a hotspot or permanently damage a module.

• Crack Faults

Glass cracks and internal cell cracks are different defects. Either may affect reliability, but not every crack produces a detectable thermal signature or the same power loss. Document the evidence and use the appropriate follow-up test.

• Contamination

Soiling is surface accumulation such as dust or bird droppings. It can reduce output without a distinct thermal anomaly; compare visible evidence and operating performance before deciding on cleaning.

• Plant Shading

Vegetation can shade modules and reduce generation. Its effect depends on the location, time of day and season; it does not necessarily stop all production or create a hotspot. Manage vegetation without damaging cables or other site equipment.

• Delamination Faults

Delamination is separation between bonded module layers. It can affect optical performance or protection against moisture and may accompany other reliability problems. It is not synonymous with a thin-film fault or proof of an imminent fire. Assess its extent and any electrical-safety concerns with qualified personnel.

Read Drone Technology and PV Panels for related guidance.

a. Visual and Thermal Inspection: Visible images can show surface damage, contamination and shading. Thermal images show temperature patterns during operation. The methods complement each other but do not independently identify every microcrack or electrical fault.

b. Electrical Tests: The electrical efficiency and connections of the panels are checked using multimeters and other test devices.

c. Weather and Operating Data: Interpret production with irradiance, temperature and operating status over the same period. A lower daily energy total during cloudy weather is not, by itself, evidence of a fault.

a. Damaged Glass or Cells: Do not treat patching a crack as a verified module repair. Qualified personnel should assess safety and performance, follow the manufacturer’s procedure and replace the module where required. Preserve photographs and identification for any warranty review.

b. Shading: Identify the obstruction and its seasonal effect before selecting vegetation management, layout changes or another suitable remedy. Verify that the chosen action is safe and permitted.

c. Elimination of Power Drop and Efficiency Problems: Power drop and efficiency issues can be reduced by cleaning, maintaining and upgrading the panels.

d. Connection Points: Qualified personnel should inspect and service electrical connections under the site isolation procedure and manufacturer instructions. Do not disconnect DC connectors under load or indiscriminately re-tighten terminals.

e. Moisture Ingress: Investigate the damaged enclosure, seal or module construction. Applying sealant over a suspected module leak is not proof that insulation or reliability has been restored. Follow the manufacturer’s assessment and replacement requirements.

Use manufacturer requirements, site risks and operating evidence to set inspection and cleaning intervals. Additional checks may be appropriate after storms, recurring alarms or unexpected production losses; no single several-times-a-year rule fits every plant.

Professional Support:

Electrical fault diagnosis and repair should be performed by qualified personnel, not only when a fault appears complex. Follow the site safety procedure and manufacturer instructions. The NREL O&M guide covers safety, maintenance planning and documentation.

Data from RGB inspections generally show physical damage to solar panels. This can include things like broken glass, chipped edges, bird droppings and scratches. Such defects reduce the amount of light the solar panel can capture, which in turn reduces the amount of power it can generate.

Microcracks can form during manufacturing, transport, installation or service. Follow the specific manufacturer’s packaging, lifting, storage and mounting instructions. Cell cutting and interconnection designs alone do not establish which module is least likely to crack; durability also depends on construction, qualification and handling.

Thermal inspection in solar power plants is a widely used method to detect potential damage to PV panels. Thermal drones measure apparent surface temperatures, and MapperX uses AI-assisted analysis with human review to identify suspected anomalies. For example, damage to a cell can often show up as a high temperature difference, but this alone does not confirm cell damage. Results depend on operating conditions, data acquisition quality and validation. Verified findings can guide repairs that support improved power generation.

Preparation: Prior to the inspection, it is important to select the right equipment and determine favorable weather conditions. The correct calibration of thermal cameras should also not be forgotten.

Flight Planning (with Drones): Flight planning operations should be carried out in accordance with the flight plans determined by MapperX. Drones are used for fast and efficient thermal inspection of solar power plants. When planning the flight path, it is important to shoot the panels at the optimum angle and to have full coverage.

Data Collection: The drone measures the surface temperatures of PV panels with a thermal camera. This data is analyzed with MapperX software and panels with abnormal temperature values are detected.

Analysis and Reporting: The data obtained is analyzed with MapperX using AI assistance and human review to identify suspected anomalous areas. Based on this data, a detailed report is created. The report includes the observed extent, suspected type and location of anomalies; damage classification requires appropriate validation.

Production Defects: Although PV panels are designed against manufacturing defects, some errors in mass production affect the quality of the products.

Transportation and Installation: Panels can be damaged during transportation from the manufacturing plant to the power plant and during installation. This shortens the service life of the panels.

Materials and Construction: Module reliability depends on material compatibility, manufacturing quality and design. Material thickness or purchase price alone does not establish whether a module is durable or defective.

PV modules can generate with diffuse daylight as well as direct sunlight. Clouds and fog usually reduce irradiance, while snow covering a module can block light. Weather-related output reduction should be distinguished from physical damage or degradation.

Dirt, dust and bird droppings that accumulate on the surface of solar panels prevent sunlight from reaching the panel surface directly. These factors reduce the efficiency of the panels, reducing energy production. Especially in rural areas, birds land on the panels, causing such problems.

Tree branches, stones or other objects can cause physical damage to the panels. Cracks or fractures affect the internal structure of PV panels and negatively impact their performance. Such damages occur more frequently, especially after natural disasters.

High cell temperatures generally reduce crystalline-silicon power at comparable irradiance. Colder cells can produce higher voltage, so string design must account for the equipment’s voltage limits under the applicable conditions. Extreme weather and thermal cycling can also create mechanical stresses; cold is not simply a universal cause of reduced PV efficiency.

Panels can also be affected by electrical problems. Problems such as overvoltage, short circuits or under-voltage can greatly reduce the efficiency and durability of the panels.

These environmental variables can lead to a series of failures and faults in solar panels. Therefore, it is important to ensure the correct functioning of the panels through regular maintenance, thermal inspections, cleaning and technical inspections.

Quality manufacturing, suitable materials and correct handling and installation reduce avoidable failure risks. They do not guarantee fault-free lifetime operation; inspection and maintenance remain part of asset management.

Thermal inspection identifies patterns that may indicate cell, substring or connection problems. An apparently normal thermal image does not prove every circuit is healthy, and an abnormal image does not establish one root cause without operating context and follow-up.

Healthy modules need not have exactly equal surface temperatures. Compare modules with similar irradiance, mounting and operating conditions, and account for reflections and environmental variation. A temperature difference is evidence to interpret, not an automatic failure verdict.

PV panel inspection is a method used to check the physical condition of solar panels. In inspections, the surface of the panels is checked for cracks, breaks, contamination or other physical damage.

1-Installation Errors: Problems caused by improper installation or assembly of PV panels.

2-Local Shading: Keeping the panels under shade during certain hours can reduce efficiency.

3-Panel Contamination: When dust, bird droppings or other external factors cover the surface of the panels, it can cause a decrease in energy production.

4- Nearby Vegetation: The shadow cast on the panels by the overgrowth of plants negatively affects energy production.

5. Cracking: Broken module glass can compromise weather protection, while internal cell cracks may affect current flow without breaking the outer seal. Distinguish these conditions when planning follow-up.

6-Manufacturing Defects: Errors made during the production phase of the panels can reduce durability or cause various problems.

7-Weather Events: Natural disasters such as lightning, hail or wind can cause damage to panels.

8. Grounding and Bonding: Defects in the required grounding, bonding or protective arrangements can create shock risks and impair fault protection. Verify these electrically under applicable design requirements; an aerial image cannot prove adequate grounding.

9-Module Degradation: Separation or damage to the layers inside the panels reduces efficiency.

10-Fuse or Connector Failure: Failures in the fuses or connectors in the electrical circuit of PV panels can affect performance by interrupting the energy flow.

Check survey coverage, image quality and localization before accepting automated findings. Report uninspected or uncertain areas explicitly rather than treating the absence of a reported anomaly as proof of a healthy plant.

MapperX is an AI-assisted software solution for thermal inspection and suspected fault detection in solar power plants. It automatically highlights suspected anomalies in inspection imagery for human review. Results depend on operating conditions, data acquisition quality and validation; thermal anomalies alone do not confirm a fault or its root cause.

AI-Assisted Findings: MapperX analyzes thermal and visible imagery to highlight suspected anomalies. It cannot infer every cell, concealed cable or internal inverter fault from surface images; correlate findings with equipment records and field checks.

Digital Asset Records: A digital representation can link modules to inspection findings and maintenance history. A periodically captured image is not a live sensor feed, so it does not by itself show real-time electrical performance or predict future faults.

What evidence should be preserved before a suspected faulty module is replaced?

Keep the module identifier, location, visible and thermal images, operating conditions, relevant electrical results and the technician’s diagnosis. Retain warranty and commissioning records and follow the manufacturer’s handling instructions for the removed component.

Can a thermally normal module still have an electrical defect?

Yes. Some defects do not produce a detectable temperature contrast under the survey conditions. Use operating data and targeted electrical or electroluminescence testing when the symptom or risk warrants it.

• PV Panel Fault Detection: Thermal and Electrical Methods