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Diagnosing hardware failures in PV systems using I-V curve tracers P hotovoltaic (PV) systems are
Case study: 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 such as high winds or hail. These cracks can grow over time, leading to reduced performance and potential failure. Symptoms: • Stepped or irregular I-V curve: The I-V curve may show steps or irregularities, indicating current mismatch. • Reduced current output (Isc): The overall current output may be lower than expected. Troubleshooting steps: 1. I-V curve tracing: Identify deviations and steps in the I-V curve. 2. Electroluminescence testing (EL): EL testing applies a reverse-bias current to a string of modules and uses a specialised camera to detect microcracks. This is the most accurate way to detect microcracks, but EL equipment is currently expensive, and the test is labour-intensive. 3. Infrared (IR) imaging: Use an IR camera to detect hot spots, which may be indicative of microcracks. 4. Replacement: Replace modules with significant microcracks. Case study: A utility-scale PV farm experienced a gradual decline in performance. I-V curve tracing and IR distribution equipment, lighting systems, and power transfer infrastructure as major ignition sources. Understanding core material risk The report evaluates the fire performance of several common combustible-core sandwich panel materials, including expanded polystyrene (EPS), polyurethane (PU), polyisocyanurate (PIR), phenolic foam, mineral wool and vacuum insulated panels. A central focus is the Limiting Oxygen Index (LOI), which measures the minimum oxygen concentration required to sustain combustion. Materials with an LOI below 24% are considered capable of sustaining combustion in normal atmospheric conditions, while higher-LOI materials are less likely to propagate fire. The report distinguishes between standard EPS cores and fire-retardant EPS products. While standard EPS can sustain combustion and contribute to fire spread, fire-retardant EPS with an LOI above 24% will generally self- extinguish once an ignition source is removed. Van Niekerk notes that many misconceptions exist regarding combustible-core sandwich panel systems. “Most combustible sandwich insulation panels are not structurally integral to
subject to various hardware issues that can significantly impact their performance. Diagnosing these issues accurately is crucial for maintaining system efficiency and longevity. I-V curve tracing is a powerful tool that helps technicians identify specific hardware failures in PV systems. This article provides a detailed guide on troubleshooting common hardware issues using I-V curve tracers. Common hardware issues in PV systems PV systems can experience several module-related problems that affect their performance. Here are some of the most common issues: Shorted Bypass Diodes Bypass diodes are integrated into PV modules to protect cells from overheating and damage caused by partial shading or internal module issues. A shorter bypass diode can cause significant performance issues, leading to reduced output voltage. Symptoms: • Low open-circuit voltage (Voc): The I-V curve will show a significantly lower Voc. • Stepped I-V curve: The curve may display steps or abrupt changes in slope. Troubleshooting steps: 1. I-V curve tracing: Use the I-V curve tracer to identify deviations in the Voc and detect steps in the I-V curve. 2. Visual inspection: Inspect the module for visible signs of damage or overheating. 3. Multimeter test: Test the bypass diodes with a multimeter. A shorted diode will show continuity in both directions. 4. Replacement: Replace the affected module or bypass diode as necessary. engineering consultancy ASP Fire is challenging blanket assumptions around combustible-core sandwich panels, arguing instead for a rational, risk- based approach that balances fire safety requirements with commercial realities in sectors such as agriculture, manufacturing and industrial processing. Authored by ASP Fire CEO Michael van Niekerk, the report assesses the relative risks associated with various combustible- core sandwich panel materials and outlines practical fire prevention and mitigation strategies for existing and new buildings. “Combustible-core sandwich panels are not without risk, but careful selection and the implementation of sound fire protection strategies can reduce those risks to levels that are as low as reasonably practicable,” says van Niekerk. The report notes that plastic-based construction materials, particularly insulated panel cores, have long presented challenges for fire engineers. However, van Niekerk argues that the focus should shift from simplistic material bans towards understanding ignition sources, fire propagation risks and practical engineering controls. According to the report, the leading causes of industrial fires remain electrical failures and heat-source malfunction, rather than the combustible-core sandwich
: I-V curve tracing is a powerful tool that helps technicians identify specific hardware failures in PV systems.
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 reduced performance. Symptoms: • Low voltage ratio: The I-V curve will show a lower-than-expected voltage ratio (Vmp/Voc). • Irregular I-V curve: The curve may display irregularities or a lower-than- expected current output. Troubleshooting Steps: 1. I-V curve tracing: Identify irregularities in the I-V curve. 2. Visual inspection: Inspect connections for signs of corrosion, damage, or poor installation. 3. Electrical testing: Use a multimeter to test for continuity and resistance in connectors. structural integrity remains dependent on the steel, concrete or masonry framework.” The report also stresses that combustible- core sandwich panels typically become significantly involved only after flashover conditions are reached within a building, generally at enclosure temperatures above 600°C, by which point the building’s contents are already contributing substantial heat release. Practical mitigation strategies Rather than advocating the wholesale replacement of combustible-core sandwich panels, the report outlines layered fire prevention and suppression strategies that can substantially reduce ignition risk. Recommended interventions include: • Rigorous electrical inspection, monitoring and thermal scanning programmes • Earth leakage, arc fault detection devices and overload protection systems • Thermal CCTV monitoring linked to 24/7 response capability • Early warning fire detection systems linked to 24/7 response capability • Automatic gaseous suppression within electrical distribution boards • Improved compartmentalisation • Spark-arresting and ember-trap systems for direct, solid-fuel heating applications
4. Thermal imaging: Use a thermal camera to detect connectors that are operating at a higher temperature when compared to other connectors under the same environmental conditions. 5. Replacement or repair: Repair or replace faulty connectors. 6. Case study: A solar carport installation had inconsistent performance. I-V curve tracing showed irregular I-V curves. Inspection revealed corroded connectors. Replacing the connectors restored consistent performance. Conclusion I-V curve tracing is an invaluable tool for diagnosing module failures in PV systems. By identifying specific issues such as shorted bypass diodes, microcracks, connector failures, PID, and hotspots, technicians can take targeted actions to restore and optimise system performance. Regular use of I-V curve tracers, combined with thorough inspections and appropriate repairs, ensures that PV systems operate efficiently and reliably.
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Balancing fire safety and commercial reality in combustible-core sandwich panels A new technical report by fire panels themselves. Citing NFPA research on industrial and manufacturing fires between 2017 and 2021, the report highlights electrical the building itself,” he explains. “In many cases they function as cladding or internal environmental enclosures. The actual • Sprinkler protection where building size or storage height thresholds require it. The report argues that these measures can often offer a more practical and cost-
effective way to reduce risk than the wholesale replacement of combustible- core sandwich panels, particularly in commercially marginal industries. “Low-margin sectors such as poultry production simply cannot absorb the cost of replacing entire building envelopes with premium non-combustible systems,” says van Niekerk. “The engineering challenge is therefore to identify and manage the real ignition and propagation risks appropriately.” Commercial realities remain critical The report further highlights the cost differential between core materials. According to the assessment, polyurethane and PIR panels can cost up to nearly double the price of fire-retardant EPS systems, while mineral wool and vacuum-insulated panels can be even more expensive. At the same time, some non-combustible solutions may not be technically suitable in certain environments. Mineral wool and glass wool systems, for example, can be problematic in high-humidity or condensation-prone applications due to the risk of mould formation.
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SPARKS ELECTRICAL NEWS
JULY 2026
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