Electroluminescence ImagingDark frames, subtracted
Every run also takes frames with the bias off and removes them. Stray light and sensor offset do not end up in your picture.
Electroluminescence Imaging
Every cell, every crack, in one picture.
A 65-megapixel electroluminescence picture of the whole panel, 0.2 mm per pixel, at two currents in one run. Then the anomaly analysis compares it with a reference of its panel type and tells you what is wrong, where, and how much it costs the cell.
65 MP
picture of the whole panel
11 232 x 5 804 px for a 2.3 m module
0.21 mm
per pixel
4.8 px/mm from corner to corner
5 MP
per camera
45 synchronised cameras on the bench
2 shots
per run, or up to 8
Isc and 0.1 x Isc by default
~3 s
anomaly analysis
per shot, cell by cell
Move over the cell, or touch it, to look closer.
Zoom into one cell. Then keep zooming.
This is one half-cut cell of the panel, cut straight out of the picture at its native resolution, no upscaling, shown with the viewer's default display sharpening. 462 x 900 pixels for a 91 x 182 mm piece of silicon, about 415 000 pixels. Every camera of the bench is a 5-megapixel sensor with wide-angle optics close to the panel, so the pixels go to the silicon, not to the distance.
- 4.8 px/mm
- across the whole panel, from corner to corner
- 462 x 900 px
- for one half-cell, about 880 x 880 px for a full M10 cell
- 0.21 mm
- per pixel: a crack is seen, located and measured in millimetres
- 65 MP
- opened instantly at any zoom, from the panel to the pixel
In this cell: a curved micro-crack running from the top edge, a T-shaped inactive area across a busbar, and small dark spots. Every busbar line is resolved.
Exposure that fits the panel
Each panel type has its own exposure, found by the station itself with a few test shots. No saturated cells, no wasted dynamic range.
It tells you when a shot is wrong
Saturated pixels, a lead off the panel, a camera that did not answer: the shot is flagged with a sentence a technician understands, kept for diagnosis and never analysed as if it were good.
Two currents, two truths
High current shows cracks and inactive areas. Low current shows what high current hides: shunts, weak cells and cells that drop out. An electroluminescence recipe takes both in the same run, with the panel never moving, so the two pictures line up pixel for pixel.
Isc (8 A)0.1 x Isc (0.8 A)Up to 8 shots per recipe
Current as a fraction of the panel's Isc or in amperes, voltage limit, exposure: one recipe per panel type, picked automatically with the DUT.
One bias window
Dark frames once, then each shot in turn, with waits that end as soon as the light is steady. The run is short and the panel stays put.
Delta images
Divide one shot by the other, or a panel before and after a stress test, cell by cell with levels matched, to see exactly what changed.
The anomaly analysis
Every picture is compared with a reference of its panel type, made from pictures of good panels. What is not as expected is painted on the picture, fine things in fire, broad areas in cyan, then sorted into findings and scored cell by cell. No threshold to tune per defect, no rule to write.
Point at a cell for its quality index and what was found in it.
One number per cell
Each cell gets a quality index: 100 % is a perfect cell, 0 % no cell at all. A cell that is only a little darker as a whole loses nothing, a crack counts by its length, a dead area by its size. Sort by it, bin by it, stop the line on it.
Two shots know more than one
When a run has two shots, the software puts their analyses together.
87
findings confirmed
Found in both shots of the run, so they are not the noise of one frame. One switch hides the small marks that only one shot shows.
Shunt
darker at low current
A cell or a patch that is darker at 0.8 A than at 8 A is tagged as a shunt, with both percentages written next to it.
Rs
darker at high current
Darker at 8 A than at 0.8 A is a series resistance: a contact or interconnection problem, not the silicon.
Delta: what changed between two pictures
Divide one picture by the other and the software shows, pixel by pixel, where the panel behaves differently: the 8 A shot against the 0.8 A shot, or the same panel before and after a stress test. Both pictures are first brought to the same level, and where that level is taken decides what you see.
The delta of the example run, 8 A divided by 0.8 A, computed from the two real pictures with the software's default settings.
Before and after a stress test
Any two results of the same panel can be compared: before and after damp heat, thermal cycling or a mechanical load. The pictures are lined up on the corner of the panel.
Four ways to match the levels
Each cell, around each point for the finest detail only, the whole panel, or as taken. Ratio or difference, smoothing, cell borders left out, range and threshold are all yours to set.
The cells that changed most
Next to the picture: a histogram of the delta, its mean and spread, the share of the panel beyond the threshold, and the twelve cells that changed most, one click to open each.
Cells worth a closer look
Four cells of the example, at native resolution. Hover a picture to take the map away and see what is under it.
B24 · 8 AQuality index59.3 %
A strip broken off
A large part of the cell is cut off and dark: a broad area in cyan. The lowest cell of the panel at 8 A.
- Dark patch
- Spot
- Dark cell
B22 · 8 AQuality index67.4 %
Several cracks
The curved crack and the T-shaped one of the close-up above, traced in fire, with small spots around them.
- Crack
- Spot
- Dark patch
C12 · 8 AQuality index71.7 %
A crack and a degraded part
A long crack with a degraded part beside it, 30 % darker than the rest of the cell, as dark at both currents.
- Degraded part
- Spot
- Crack
C23 · 0.8 AQuality index27.4 %
A shunt
59 % darker than a typical cell at 0.8 A and only 8 % at 8 A: darker at low current, so the software calls it a shunt.
- Degraded part
- Crack
- Dark cell
Hover to hide the map
A viewer built for metrologists
The electroluminescence workspace sits next to the IV results in PVStudio.
Deep zoom
Tiled image pyramid: the full 65 MP picture pans and zooms without waiting.
Cell loupe
Hover any cell to enlarge it, step from cell to cell with the keyboard.
Colour maps
Grey, inferno, magma, viridis, turbo and more, with levels and contrast equalisation: for the eye only, the data is never re-encoded.
Anomaly layers
Fine and broad layers, threshold, colours, and a key to hold the map away and see what is under a mark.
Visible-light overlay
Attach and align a normal photo of the panel to compare with the electroluminescence picture.
Export
PNG, TIFF or JPEG of any result at full resolution, for your reports and your customers.
Your operator has the last word
Kinds can be hidden, and operators add their own marks on the picture. The marks are saved with the result.
In the measurement file
The electroluminescence shots are taken in the same run as the IV curve and saved in the same measurement, so a module's power and its picture never get separated.
Better with every release
The analysis engines arrive as signed, encrypted packages through Pasan Cloud. Your station improves without a reinstall.
Works with our simulators
Electroluminescence Imaging runs in PVStudio beside the I-V measurement, on the same station and in the same measurement file.
Built around the electroluminescence standards
Electroluminescence imaging of PV modules has its own IEC technical specification, and qualification labs use it before and after every stress test. Electroluminescence Imaging is made for both.
IEC TS 60904-13
Electroluminescence of photovoltaic modules: the module in forward bias in the dark, a camera that sees the near infrared, one picture at Isc and one at a lower current. Our electroluminescence bench takes exactly that pair, Isc and a tenth of Isc, in one run.
IEC 61215-2 and IEC 61730-2
Qualification and safety testing: thermal cycling, damp heat, mechanical load. Labs image a module before and after each sequence; the delta compares the two pictures cell by cell and shows what the stress did.
IEC 60904-1
The I-V curve of the same run, measured on the Nexun or HighLIGHT simulator, is saved in the same measurement as the electroluminescence pictures: power and picture of one module, never separated.
From the people who calibrate the world's flashers
Pasan has built the reference solar simulators for module makers and test labs since 1978, and Avalon ST has made full-LED simulators since 2018. Electroluminescence Imaging comes from the same engineers: the cameras, the bench electronics, the analysis and the software are designed in-house, and we measure on them every day.
- Designed by the team behind PVStudio, the software that runs our Nexun and HighLIGHT systems
- In-house analysis engines, updated over the air
- Fitted to almost every Nexun vertical system we ship
- Supported remotely by the engineers who wrote it
See your own panel in it
Send us a module, or ask for the full-resolution example, and judge the detail for yourself.