EL Fundamentals
Fundamentals of PV electroluminescence: imaging principle, daytime vs night EL, EL vs IV testing.
EL Wavelength and the Silicon Emission Spectrum
Silicon EL emits around 1150nm, set by its bandgap. This wavelength choice drives camera selection and daytime filtering strategy. This article explains the silicon emission spectrum.
Read more →Photoluminescence (PL) vs Electroluminescence (EL) Inspection
Both PL and EL make cells luminesce, but PL uses light excitation while EL uses current injection. This article compares them and explains where each fits.
Read more →What Is the InGaAs SWIR Camera Used in EL Imaging?
EL imaging needs a camera sensitive to ~1150nm near-infrared—InGaAs SWIR cameras fit this range. This article explains what InGaAs cameras are and why they suit EL.
Read more →What Resolution and Signal-to-Noise Ratio Mean in EL
Resolution decides how fine a defect you can see; SNR decides whether you can see it at all against noise. This article explains both and why they matter, especially for daytime EL.
Read more →Why Can EL Find Defects Invisible to the Naked Eye?
EL sees electrical defects, not surface appearance—so hidden cracks, broken gridlines and inactive areas that look fine visually show up as dark regions. This article explains why.
Read more →Reading Cell Gridlines in EL Images
Gridlines collect current from the cell, and EL reveals whether they work—broken or poorly contacted gridlines show as dark bands. This article explains how to read gridlines in EL.
Read more →How Exposure Time Affects EL Image Quality
Longer exposure gathers more of the weak EL signal but risks blur and lower throughput; shorter exposure is faster but noisier. This article explains the exposure trade-off in EL.
Read more →How EL Works: Why Silicon Cells Emit Near-Infrared Light
EL imaging works because silicon cells emit near-infrared light via radiative recombination when forward-biased. This article explains the physics behind EL in plain terms.
Read more →The Current Injection Principle in EL Inspection
EL requires forward-injecting current into a module to trigger luminescence. This article explains how much current, why it matters, and how injection level affects imaging.
Read more →What Do Bright and Dark Areas Mean in EL Images?
In EL images, brightness maps to electrical quality—bright means healthy, dark means defective or inactive. This article explains how to read EL brightness correctly.
Read more →Rear-Side EL Imaging of Bifacial Modules
Bifacial modules generate power from both sides, so rear-side EL imaging can add diagnostic value. This article explains rear-side EL considerations for bifacial modules.
Read more →What Is EL Inspection? PV Electroluminescence Imaging Explained
EL (electroluminescence) inspection forward-biases a PV module so silicon emits near-infrared light; a SWIR camera images internal defects invisible to the eye.
Read more →What Defects Can EL Inspection Find? Cracks, Gridlines, PID and More
A practical guide to the module defects EL imaging reveals — hidden cracks, micro-cracks, broken gridlines, cold solder, black cells, PID — and how each appears on the image.
Read more →How to Detect Hidden Cracks in PV Modules — Causes, Risks, Methods
Hidden cracks are invisible to the eye but shorten module life. EL imaging is the most direct way to find them. This article covers causes, risks and detection.
Read more →What Is PID? Detecting Potential-Induced Degradation with EL
PID (potential-induced degradation) silently robs plant output after years of operation. EL imaging shows its tell-tale edge-to-center darkening pattern.
Read more →