Solar PV fault detection: Diagnosing hardware failures with Fluke I-V curve tracing – Comtest
PHOTOVOLTAIC (PV) systems are built for long-term performance, but even minor hardware faults can reduce output and lead to significant energy losses if left undetected. Effective troubleshooting is essential to maintain efficiency, minimise downtime, and protect long-term return on investment.
One of the most powerful and accurate diagnostic methods available today is I-V curve tracing. The Fluke I-V curve tracer, supplied by Comtest, analyses the current-voltage relationship of a PV module or string, enabling technicians to quickly identify underlying faults and take corrective action.
Key PV system faults that impact performance and energy yield
PV systems can experience several module-related problems that affect their performance. Some of the most common issues are shorted bypass diodes, microcracks in PV cells, connector failures, Potential Induced Degradation (PID), and hotspots.
Shorted bypass diodes
Bypass diodes are integrated into PV modules to protect cells from overheating and damage due to partial shading or issues within the module. A shorted bypass diode can cause significant performance issues, leading to a reduced voltage output.
In a commercial PV installation, technicians noticed a drop in system performance. I-V curve tracing revealed a low Voc in one string. Testing the bypass diodes confirmed a shorted diode. Replacing the affected module restored the system’s performance.
Microcracks in PV cells
Microcracks are small cracks in PV cells that can occur during manufacturing, transportation, and installation and due to weather events like high wind or hail. These cracks can grow over time, leading to reduced performance and potential failure.
A utility-scale PV farm experienced a gradual decline in performance. I-V curve tracing and IR imaging identified microcracks in several modules. Replacing these modules improved the system’s overall output.
Connector failures
Connectors are critical components in PV systems. Failures can result from corrosion, poor installation, or physical damage, leading to increased resistance and system underperformance.
A solar carport installation experienced inconsistent output. I-V curve tracing revealed irregular I-V curves, with inspection confirming corroded connectors. Replacing the connectors restored normal system operation.
Potential Induced Degradation (PID)
PID is a phenomenon that occurs when voltage differences between the PV system and the ground lead to leakage currents, causing module degradation.
A PV farm in a high-humidity area experienced significant PID. I-V curve tracing and IR imaging confirmed the issue. Installing PID mitigation equipment and replacing severely affected modules restored optimal operation
Hotspots
Hotspots occur when a part of a PV module becomes significantly hotter than its surroundings, often due to shading, soiling, or cell damage, leading to reduced performance and possible damage.
A residential PV system had reduced output. I-V curve tracing and IR imaging identified hotspots caused by bird droppings and a cracked cell. Cleaning the array and replacing the affected module resolved the issue.
Protecting solar assets with precision fault detection
Regular use of I-V curve tracing, combined with thorough inspections and targeted corrective actions, enables technicians to quickly identify faults, reduce downtime, and maximise energy yield—ensuring PV systems operate at optimal performance over their lifespan.
For more information, demonstrations, or locating your nearest authorised Comtest Channel Partner, contact COMTEST on + 010 595 1821, sales@comtest.co.za or visit www.comtest.co.za
