Defect Reading
How micro-cracks, broken gridlines, black cells, hot spots and PID appear in EL images and how to read them.
EL Inspection of Shingled PV Modules
Shingled modules overlap cells with conductive adhesive instead of ribbons, changing what EL images reveal. This article explains shingled structure, typical defects and EL inspection points.
Read more →Post-Disaster EL: Checking Modules After Hail and Storms
Hail and storms can induce hidden cracks that look fine visually but cause long-term power loss. This article explains why post-disaster EL is essential and how to run it.
Read more →How PID Degradation Forms and Whether It Can Be Recovered
PID (potential induced degradation) is often partially recoverable if caught early. This article explains how PID forms, how EL reveals it, and the conditions for recovery.
Read more →EL Inspection Outlook for Perovskite and Tandem Modules
Perovskite and tandem modules bring new luminescence physics and defect types. This article explores the outlook for EL inspection of these next-generation technologies.
Read more →EL Inspection Differences Between N-type and P-type Modules
N-type modules (TOPCon, HJT) differ from P-type in luminescence characteristics and defect patterns. This article explains how EL inspection adapts to N-type technology.
Read more →Detecting Module Mismatch and Efficiency Inconsistency with EL
Mismatched or inconsistent cells drag down a module's and string's output. This article explains how EL reveals brightness inconsistency and why mismatch matters.
Read more →Is Edge Darkening in EL Always PID?
Edge darkening in EL is a classic PID sign, but not the only cause—cracks, process issues and shading also darken edges. This article explains how to tell them apart.
Read more →EL Inspection of Double-Glass PV Modules
Double-glass modules replace the backsheet with glass, changing mechanical behavior and defect patterns. This article explains double-glass structure and EL inspection considerations.
Read more →Telling Broken Gridlines from Cracks in EL Images
Broken gridlines and hidden cracks both show as dark features in EL but differ in shape and cause. This article explains how to distinguish them for correct grading.
Read more →EL Inspection for Large-Format Modules (182/210)
Large-format 182mm and 210mm modules carry higher current and larger areas, raising demands on EL field of view, uniformity and handling. This article explains what to watch for.
Read more →EL Inspection for Half-Cell Modules
Half-cell modules split cells to cut resistive loss, but the cut edges and doubled cell count change EL reading. This article explains what's different when inspecting half-cell modules with EL.
Read more →How Are PV Module Defects Graded? An EL Defect Classification Guide
A defect grading system sorts EL findings by severity—from cosmetic to power-critical—so results are actionable. This article introduces a practical A/B/C grading logic for EL inspection.
Read more →How Power Degradation Relates to EL Defects
Power degradation often traces back to specific EL-visible defects—cracks, PID, corrosion. This article connects measured power loss with EL findings and explains how the two diagnose each other.
Read more →Do Hidden Cracks Propagate? Transport Vibration and Crack Growth
Hidden cracks can propagate under thermal cycling and mechanical vibration, turning low-risk cracks into isolated dead zones. This article explains crack growth and why before/after EL comparison matters.
Read more →Detecting Ribbon Misalignment and Breakage with EL
Interconnect ribbon defects—misalignment, breakage or lifting—disrupt series current and show up as dark cells or dark edges in EL images. This article explains their causes and EL signatures.
Read more →Spotting Cell Printing Defects and Scratches with EL
Screen-printing defects and scratches on cells create localized dark lines or patches in EL images, often present from the factory. This article explains their causes and how EL reveals them.
Read more →What Is Delamination? Detecting EVA Delamination
Delamination is the separation of encapsulant layers inside a module, letting moisture in and accelerating degradation. This article explains its causes, how it relates to EL findings and how to confirm it.
Read more →What Are Snail Trails? Their Link to Hidden Cracks
Snail trails are dark discoloration lines on the module surface, often tracing underlying micro-cracks. This article explains their formation, the crack connection and how EL confirms the real damage.
Read more →Types of Hidden Cracks in PV Modules and Their Risks
Hidden cracks come in linear, branching and cross patterns, each posing different risks to power output. This article classifies crack types by their EL signatures and explains which ones matter most.
Read more →Detecting Virtual Solder Joints with EL Imaging
Virtual (cold) solder joints raise contact resistance and interrupt current flow, showing up as localized dark spots or dark cell edges in EL images. This article explains their causes, EL signature and risk.
Read more →Identifying Cell Fractures with EL Imaging
Cell fracture is a fully-developed crack that electrically isolates part of a cell, leaving clearly dark disconnected islands in EL images. This article explains how to tell fractures apart from micro-cracks.
Read more →What Is Gridline Breakage? Spotting It with EL Imaging
Gridline breakage cuts the current-collection path inside a cell and shows up as dark fingers or dark regions in EL images. This article explains its causes, EL signature and impact on power.
Read more →Black Cells in PV Modules — How EL Imaging Reveals Them
A "black cell" appears fully or partially dark in EL images, signalling an open circuit, severe crack or connection failure. This article explains the causes and how EL distinguishes black cells from other defects.
Read more →PV Module Hot Spots — Causes and the Role of EL Inspection
Hot spots are localized overheating that can scorch a module and cause fire risk. This article explains their causes, why infrared finds them and how EL locates the underlying defects that trigger them.
Read more →EL Inspection for HJT Modules — What to Watch For
HJT cells have a low-temperature, temperature-sensitive structure that calls for tighter control of injection and temperature during EL, and awareness of luminescence differences versus PERC. This guide covers the key points.
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