Most Faults Remain Invisible to Conventional Analysis
Despite manufacturer promises of “robust,” “maintenance-free” operation, field data reveals that over 75% of PV installations experience performance losses exceeding 10% within three years of commissioning. Even brand-new systems often show 5% losses at the commissioning stage, yet these problems remain undetectable through visual inspection or basic electrical testing.
The fundamental challenge lies in measurement limitations. Traditional inspection methods – visual assessment, thermal imaging, and single-channel IV measurements – cannot capture the complex interactions that drive real-world performance degradation. Mismatch losses between strings create amplification effects where one underperforming component reduces entire array output by factors far exceeding its individual contribution.
Modern power electronics operate at switching frequencies between 2-20 kHz, generating emissions and creating impedance variations that affect system behavior in ways that conventional 50 Hz-focused analysis completely misses. Meanwhile, the proliferation of high-capacitance module technologies (N-Type, HJT, TOPCON) requires measurement capabilities that exceed traditional IV curve tracer specifications for both voltage handling and current response speed.
Multi-channel synchronized measurement with 2200-point resolution captures phenomena invisible to standard approaches. String interactions, impedance variations, and subtle fault signatures become quantifiable when measurement precision matches the complexity of modern PV systems. This resolution difference – 2200 points versus industry-standard 128 – determines whether critical transitions appear in measurement data or remain hidden.
High-frequency analysis extending to 150 kHz reveals emissions and impedance characteristics that affect long-term reliability and grid compatibility. Equipment that appears compliant under traditional harmonic analysis may violate IEC 61000-2-2 compatibility levels in frequency ranges that utility infrastructure cannot accommodate as renewable penetration increases.
Leakage current measurement with distance-to-fault capability identifies safety hazards before they escalate into fire risks or electrical shock dangers. Regular assessment of earth leakage patterns provides early warning of insulation degradation that threatens both personnel safety and system availability.
This technique will record the voltage and current profile (IV curve) of PV panels starting at the open-circuit voltage (Voc) to the short-circuit current (Isc) by applying a load. Depending of the shape of the curve, the different possible faults can be detected and differentiated. Further it’s the only method to detect mismatch losses.
The following picture shows an example of a simultaneous measurement of a PV array with 17 strings.
While using single-channel IV tracing systems will take a lot of time (days) for inspection of solar farms (e.g. 400 strings for 3 MW) the muti-channel IV-curve tracing system will allow inspection of solar power plants within very short time (~4 hours per MW) and will give valueable information about the mismatch losses.
The patented diagnostic system automatically shows the condition of each string. Different colours outlines the string performance and shows different PV module faults.
Fault detection: Mismatch, PID, Hotspot, Bypass diode breakage, Shading, Soiling, Glass breakage, Delamination, Cell Crack etc.
Inspection of solar PV parks are divided in several disciplines. First of all the system needs to be checked for any safety issues. Leakage currents and isolations faults can be dangerous people and can also affect other equipment like pipelines. Further performance limiting faults like PID, Hotspots, broken, bypass diodes etc. should be detected and the performance of the whole system according to IEC62446-2 analysed.
Mounting hardware creates subtle shading patterns that significantly impact PV performance while remaining invisible to conventional testing methods. These slight shadows from clamps, rails, and structural components generate characteristic “kinks” in IV curves that standard measurement systems cannot resolve.
Traditional IV curve analyzers using 128 measurement points miss critical transitions where mounting shadows activate bypass diodes. Our 2200-point sampling resolution captures these subtle current steps, revealing how seemingly minor mounting decisions create measurable power losses throughout system lifetime.
Field measurements demonstrate how mounting-related shading reduces individual module output by 8-12%, with the characteristic voltage plateau clearly visible only through high-resolution analysis. Investigation reveals that optimal mounting hardware positioning prevents these losses entirely, making detection capability essential for both commissioning verification and performance troubleshooting.
Download the complete measurement methodology and case studies showing mounting shadow identification, quantified performance impacts, and corrective strategies that restore full system performance.
Poor MC4 connector assembly creates progressive contact resistance that degrades system performance while remaining undetectable through conventional testing. These connection faults manifest as subtle IV curve distortions that only high-precision measurement can identify before they escalate into complete failures.
Contact resistance develops gradually through thermal cycling, moisture ingress, and mechanical stress, creating measurable voltage drops during current transitions. Standard measurement approaches cannot distinguish these resistance signatures from normal module variations, leaving connector problems undiagnosed until catastrophic failure occurs.
Our investigation documented MC4 connector degradation patterns showing 3-7% power losses from poor connections, with distinctive IV curve slopes that correlate directly with contact resistance values. The characteristic curve shape allows field identification of problematic connectors before they cause system shutdowns or fire hazards.
Learn the measurement techniques that reveal connector degradation patterns, understand the quantified relationship between contact resistance and power loss, and implement preventive maintenance protocols that eliminate connection-related failures.
Single underperforming strings create system-wide losses far exceeding their individual contribution due to parallel mismatch effects. Engineers consistently underestimate these amplification losses because conventional string monitoring cannot capture the dynamic interactions that reduce total array performance.
When one string in a parallel array operates at reduced capacity, the resulting voltage mismatch forces all strings to operate at suboptimal points. Our field documentation shows how a single string performing at 30% capacity reduces total 20-string array output by 27% rather than the expected 5% proportional loss.
This amplification occurs because parallel-connected strings must operate at common voltage points determined by the weakest performer. Multi-channel IV curve measurement reveals these interactions by simultaneously capturing all string performance under identical environmental conditions, quantifying losses that remain invisible to sequential testing methods.
See complete case studies demonstrating mismatch loss amplification, understand the measurement approach that quantifies system-level impacts, and learn diagnostic protocols that identify underperforming components before they compromise entire array performance.
Modern PV systems experience fault modes that produce similar symptoms but require different remediation strategies. Distinguishing between PID degradation, bypass diode failures, cell cracking, and partial shading requires measurement precision that resolves subtle curve characteristics invisible to standard testing approaches.
Each fault type creates distinctive IV curve signatures that enable differential diagnosis when measurement resolution captures the relevant transitions. PID produces gradual slope changes across the entire curve, while bypass diode failures create sharp voltage steps at specific current levels, and cell cracks generate power curve irregularities at maximum power points.
Our documented fault library demonstrates how curve shape analysis enables accurate diagnosis where visual inspection fails. Insurance documentation cases show how comprehensive electrical testing revealed storm damage beyond visually apparent module breakage, ultimately supporting additional warranty claims worth significant repair cost recovery.
Access the complete fault signature library, understand measurement requirements for reliable fault classification, and implement diagnostic protocols that distinguish between similar fault modes through quantitative curve analysis rather than symptom-based approximation.
Mismatch losses occur at serial or parallel connection of PV panels due to differing electrical characteristics. The reasons for mismatch can be: different panels, different elevation, shading, hotspots, PID, any other faults. The following picture gives an explanation of the losses due to serial (left) and parallel (right) connection:
In solar farms usually a combination of series and parallel connection of PV panels is used in order to use the full MPP input range of inverters. Via series connection panels will be connected to a PV-String. Connecting this PV strings together via parallel connection will represent a PV-Array. If now one string of the PV-array will reduce it’s output power due to any defective module or tempory shading, not only the power of this string will be reduced. The whole system voltage (parallel connection of voltage sources) will decrease and the power of the whole array decreases. In the example below the output power of the array will be reduced by 8 kW (30%) instead of 3kW (10% reduction at string) due to this Mismatch losses.
Contact our technical team to discuss your specific measurement requirements and learn how comprehensive system analysis can optimize both performance and safety in your PV installations.
📧 sales@neo-messtechnik.com
📞 +43 2642 20 301
The gap between nameplate ratings and measured performance contains both lost revenue and hidden risks that conventional testing cannot quantify. Whether you’re commissioning new installations, investigating underperformance complaints, or developing maintenance strategies for existing assets, comprehensive measurement reveals the technical reality behind performance assumptions.
Our measurement solutions provide the resolution and analysis capabilities that modern PV systems require. From multi-channel IV curve analysis to high-frequency power quality assessment, we deliver the technical insights that enable informed engineering decisions rather than symptom-based guesswork.
Thermal imaging detects only hotspots reliably, missing PID degradation, mismatch losses, cell cracks, and most bypass diode failures. Cameras require high irradiance (>1100 W/m²), calm wind, and expert interpretation to distinguish fault-generated heat from environmental variations. This measurement approach detects advanced degradation symptoms rather than electrical root causes.
Multi-channel IV curve analysis with 2200-point resolution captures electrical signatures that reveal fault conditions before thermal symptoms develop. Our measurement approach operates across wider irradiance ranges (>300 W/m²) and quantifies all major fault categories through curve shape analysis rather than symptom observation.
The synchronized measurement of up to 20 strings simultaneously reveals comparative performance under identical environmental conditions, exposing mismatch effects and degradation patterns invisible to sequential thermal scanning. Automated fault classification processes curve characteristics against known electrical signatures, identifying PID, bypass failures, and cell damage without requiring thermal imaging expertise or ideal weather conditions.
Bypass diode failures occur in two distinct modes requiring different remediation strategies. Shorted diodes permanently bypass cell groups, reducing string voltage. Open failures eliminate bypass protection, forcing shaded cells into reverse breakdown with excessive heating. Standard testing cannot distinguish between these modes, while visual inspection reveals nothing about internal diode condition.
High-resolution IV curve measurement reveals the electrical signatures that distinguish shorted from open bypass diodes through voltage transition analysis. Shorted diodes create characteristic voltage steps visible as distinct plateaus in the IV curve, with the voltage reduction corresponding precisely to the bypassed cell group count.
Our 2200-point sampling resolution captures these transitions clearly, while measurement systems using 128 points miss the critical voltage region where bypass activation occurs. The quantified voltage reduction enables immediate identification of which cell groups are permanently bypassed, guiding technicians to specific junction box locations rather than requiring module-by-module investigation across entire strings.
Potential-Induced Degradation develops gradually through voltage stress between modules and grounding systems, reducing output power by 5-10% annually. Early detection proves difficult because degradation occurs uniformly across modules, eliminating comparative reference points. Electroluminescence requires nighttime access and specialized equipment, while thermal imaging reveals symptoms only after losses exceed recovery potential.
IV curve shape analysis identifies PID through characteristic slope changes that indicate simultaneous series and shunt resistance degradation. The measurement approach compares actual curve shapes against expected performance calculated from environmental conditions and module specifications, revealing systematic deviations that indicate potential-induced stress effects.
Our analysis quantifies both the Rs decrease visible in the curve’s maximum power region and the Rsh decrease apparent in the low-voltage region, providing electrical confirmation of PID before visual inspection reveals any module discoloration. This early detection enables timely implementation of regeneration protocols or system grounding modifications while performance remains recoverable, preventing the permanent degradation that occurs when PID advances undetected.
Hotspots develop when reverse-biased cells dissipate power as heat, creating fire risks and accelerating degradation. Thermal imaging requires irradiance exceeding 1100 W/m² for reliable detection, restricting inspections to midday periods during clear weather. Wind conditions and cloud transitions create further complications, limiting inspection flexibility and forcing delayed fault detection.
IV curve analysis identifies hotspot conditions through electrical signatures rather than thermal symptoms, enabling detection at irradiance levels above 300 W/m². The characteristic curve distortion—reduced current with maintained voltage—reveals cells operating in reverse breakdown regardless of whether sufficient heat generation has developed for thermal camera detection.
Our measurement approach captures hotspot electrical signatures across morning and afternoon periods that thermal imaging cannot utilize, providing inspection flexibility that accommodates project scheduling constraints. The electrical detection identifies hotspot conditions in early development stages, before thermal cycling has degraded encapsulation and created the fire hazards that thermal imaging typically reveals only after extensive heat exposure has occurred.
All-In-One. 1MS/s. Multi-Touch. 4 hours mobile operation. The reference instrument on the market.
The world’s best mobile PV inspection instrument. Simultaneous IV curve measurement of up to 20 strings
Grid impedance analyzer for detection of resonances, connection evaluation and PLC (Power Line Communication)
Modern power electronics operate beyond conventional measurement limits, generating supraharmonic emissions that disrupt smart meters, amplify grid resonances, and violate compatibility standards. Discover how frequency-dependent impedance analysis and extended-range measurement techniques reveal interference patterns up to 150 kHz that traditional power quality analyzers cannot detect.
