Thermal Imaging Camera Technology: Detecting 7 Common Solar Electrical Faults

In solar asset management, accurate equipment condition assessment is the cornerstone of sustained performance across a 20-25 year operational lifespan. A thermal imaging camera enables engineers to localize thermal anomalies without physical intervention, enabling timely root cause analysis and eliminating recurrence risks.

This article analyzes the role of this technology and the 7 most common faults detected in the field by Electric Bird’s technical team.

The Role of a Thermal Imaging Camera in Solar System Maintenance

A thermal imaging camera (also known as an infrared thermal camera) is an essential diagnostic tool for solar system inspections. It identifies thermal anomalies across equipment without direct contact, making it one of the most efficient non-destructive survey methods available. A single thermal scan can detect multiple types of abnormalities across modules, strings, and DC/AC combiner boxes before they progress into fire hazards or serious equipment failures.

Applying this technology delivers several core values for asset owners:

• Early fault identification: Pinpoints defects originating from manufacturing (such as faulty modules), installation errors, or operational mismanagement.
• Warranty claim support: Provides clear thermographic evidence to support warranty processes, reducing material replacement costs.
• Comprehensive single-survey coverage: One thermal imaging camera inspection can identify multiple anomaly types across modules, strings, and inverter enclosures simultaneously.
• O&M performance assurance: Prevents the system from operating below its design performance baseline.

Ideal Conditions for Accurate Thermal Scanning

Collecting reliable temperature data requires strict adherence to field conditions. Deviations in irradiance or equipment calibration will compromise the validity of trend analysis.

Key conditions technical teams must observe:

• Timing: Scans should be conducted during high-irradiance periods, typically above 600 W/m². This is when inverters and equipment most clearly exhibit thermal stress and power derating behavior.
• Equipment: Use a calibrated thermal imaging camera with IR resolution and Noise Equivalent Temperature Difference (NETD) performance meeting technical standards.
• Reference standard: Apply IEC TS 62446-3 (Photovoltaic systems – Requirements for testing, documentation and maintenance – Part 3: Outdoor infrared thermography) as the evaluation framework.

7 Common Faults Detected by a Thermal Imaging Camera

Applying infrared thermal imaging in O&M operations enables the digitization of physical asset condition. Below is a detailed technical analysis of the 7 most frequently identified fault categories.

1. Localized Hotspots on Cell/Module

• Phenomenon: Current generated by healthy cells is forced through a cell with elevated internal resistance (caused by micro-cracks, silicon contamination, or semiconductor material degradation), converting energy into heat rather than electricity.
• Thermal signature: Bright spots with significant temperature differentials (typically greater than 10-20°C) compared to adjacent cells on the same module.
• Consequence: Hotspots cause localized cell degradation over time. Without timely replacement or repair, accumulated production losses compound year over year.

2. Bypass Diode Failure

• Phenomenon: Bypass diodes protect cell groups under shading conditions. When overloaded by thermal stress or reverse current, they can fail into short-circuit or open-circuit states.
• Thermal signature: An abnormal heat band appears across one-third or two-thirds of the module surface, corresponding to the cell substring protected by the failed diode.
• Consequence: A shorted bypass diode disables one-third of the module’s output capacity and significantly distorts the I-V curve of the entire string. Evaluation must be combined with open-circuit voltage (Voc) measurements to accurately quantify degradation severity.

3. String Power Loss or Open Circuit

• Phenomenon: A broken cable, blown DC fuse, or connector fault causes the complete loss of current flow through an entire string.
• Thermal signature: All modules in the open-circuit string display uniform but significantly elevated temperatures compared to normally operating strings, as no electrical energy is being exported.
• Consequence: Total loss of that string’s output capacity. Partial or intermittent open circuits generate sustained low-level string deviation that accumulates into significant mismatch loss over time.

4. Loose Connections or Thermal Overload at Junction Points

• Phenomenon: Sub-standard installation torque or material degradation over time increases contact resistance at MC4 connectors, fuses, and circuit breakers inside DC/AC combiner boxes. High ambient humidity further accelerates insulation deterioration and connector faults.
• Thermal signature: Localized hotspots at connection points reaching extreme temperatures, potentially exceeding 80-100°C depending on the degree of looseness.
• Consequence: This is the primary cause of DC arc faults and solar plant fires. Immediate remediation is required to maintain electrical safety. A handheld thermal camera is often the most practical tool for scanning combiner boxes and junction enclosures during routine O&M checks.

5. Potential Induced Degradation (PID)

• Phenomenon: Leakage current from solar cells (typically at the negative pole of the string in ungrounded negative systems) flows through the EVA encapsulant and cover glass to the grounded aluminum frame.
• Thermal signature: Scattered modules display elevated background temperatures, concentrated toward the negative terminal modules of the inverter or string. Affected cells are typically located near the aluminum frame perimeter.
• Consequence: Modules exhibit abnormal degradation rates exceeding natural aging curves. PID causes severe string voltage drop and requires intervention using Anti-PID boxes to restore performance.

6. Severe Soiling or Persistent Local Shading

• Phenomenon: Heavy dust accumulation (soiling), bird droppings, or permanent obstruction shadows (shading) cover cell surfaces continuously.
• Thermal signature: Irregular heat patterns on the module surface, geometrically matching the shaded or contaminated area.
• Consequence: Creates a current bottleneck effect across the affected cell group. Cleaning frequency should be determined by the economic threshold of soiling loss, not by a fixed schedule.

7. Structural Module Defects

Phenomenon: Mechanical impact or thermal stress causes glass breakage, internal silicon micro-cracks, or delamination of the EVA encapsulant layer.

Thermal signature: Temperature elevation along hairline micro-crack patterns or uneven heat distribution at delamination zones.

Consequence: Even when no immediate critical fault is triggered, structural defects drive performance deviation from the Year 1 baseline. These defects inevitably compound into cumulative production loss across annual cycles if left uncontrolled.

See also: How to Inspect Solar Panels Using a Thermal Imaging Camera and SCADA

Optimizing Asset Performance with Electric Bird’s Specialized O&M Solutions

Solar energy assets typically carry a 20-25 year operational lifespan. However, unstructured operations lead to escalating OPEX driven by the absence of a long-term O&M strategy. A credible solar operator focuses on risk governance rather than reactive repair after faults occur.

Electric Bird provides specialized solar O&M and asset management services. We integrate periodic thermal imaging camera inspections to detect latent risks early, optimize operational performance, and reduce degradation risk across full operating cycles.

Rather than conventional maintenance approaches, our solar operations framework centers on KPI-based performance monitoring and seasonal trend analysis, keeping PR, availability, and downtime metrics within controlled thresholds. We commit to maintaining performance within contractual bounds, delivering sustainable returns on your project investment.

The difference between a performing asset and an underperforming one often comes down to how early risks are identified. Thermal imaging camera inspections, combined with structured pv repair workflows and SCADA-integrated monitoring, form the diagnostic foundation for protecting long-term asset value.

Conclusion

Effective thermal imaging camera inspections, structured pv repair protocols, and KPI-driven monitoring are the three pillars that separate reactive maintenance from professional asset management.

If you want to protect your solar investment and maintain performance across its full lifecycle, contact Electric Bird to learn more about our specialized O&M and asset management services.

Frequently Asked Questions about Thermal Imaging Camera