PROCUREMENT NOTES
Machine vision in PV equipment: positioning, inspection and what to test
How to read camera, CCD and vision claims on stringers, layup stations, laser tools and inspection equipment.
By PVYard Editorial · Updated 2026-11-06
Two different jobs for one camera
PV equipment uses cameras for two jobs that are often described with the same words. Vision positioning measures where a part is so that a robot or axis can correct its movement. Vision inspection decides whether a part or joint is acceptable. A machine can be excellent at one and weak at the other. When a listing says "CCD" or "vision-guided", the first question is which of the two it means.
The SC-Solar vision-guided string layup station uses vision to place strings, with optional flipping, cutting and repair feeding. The Hymson TOPCon laser doping machine uses vision positioning with automated wafer transport so that the laser pattern lands in the right place. In both cases the camera supports placement. It does not, by itself, prove the electrical or process result, which is why the Hymson listing recommends separating the process result from positioning accuracy and breakage.
Reading camera accuracy figures
A "camera accuracy" number usually describes the measurement, not the finished position. Our HORAD profile makes this point for robotic layup: a precise camera says little about the final position of a string against the edges of the finished module. Mechanical play, gripper compliance, material movement during transfer and the reference used for calibration all sit between the image and the result.
Ask the supplier three things. What feature does the camera measure, and against which reference? What is the resulting placement tolerance on the finished assembly, and how was it measured? How often is calibration checked, and what happens when a part is outside the correctable range? The SC-Solar EVA repositioning station is a useful example; its listing mentions deviation ranges but no defined correctable offset or camera reference, so those values belong in the quotation.
For the camera itself, the EMVA 1288 standard of the European Machine Vision Association defines how sensor characteristics such as quantum efficiency, temporal dark noise and system gain are measured. Asking for EMVA 1288 data does not test the whole vision system, but it stops two camera datasheets from being compared on different definitions.
Inspection: define the defect and the decision
Inspection claims need a defect list. On a cell stringer, that may cover ribbon offset, missing joints and cracked cells. The Ooitech SS-1500B stringer combines automatic cell loading and CCD detection with robotic placement and infrared soldering; the buyer still has to define which defects the CCD step must catch and at what rate. On a module line, the HORAD lead-wire solder-joint inspection station and the label-verification station are dedicated visual inspection steps, each with a narrower task.
Camera checks inside a process station are smaller still. The HORAD edge-tape removal station uses a discharge camera to check whether tape was removed; the junction-box mounting station uses a 3D camera and a six-axis robot for disordered pickup. These are useful checks, but they cover one condition each. The SC-Solar insulation-sheet placement listing puts it well: accepting the physical piece, detecting it by camera and recording it for traceability are three separate checks, and one camera should not be assumed to cover all of them.
Electroluminescence imaging is a separate method. IEC TS 60904-13 describes how EL images of modules are captured, how image metrics are quantified and how features are interpreted, with the cells forward-biased by a power supply. A camera that checks placement on a layup station is not an EL tester, and crack inspection needs its own EL step.
Testing vision during acceptance
A vision test needs prepared samples: good parts, parts at the limit of the correctable range, and parts with each defect in the list. Run them blind, record the decisions and compare with an agreed reference measurement. Check the reaction to a rejected part: is it removed, flagged in the record and kept out of the next station? Include lighting and lens cleaning in the maintenance plan, because many vision faults in production come from contamination rather than software.
Vision is also central to automation suppliers outside the process equipment itself. Hikrobot presents machine vision, mobile robots and articulated robots as separate businesses, and its ingot transfer robot series sits in wafer handling. For any of these, the question remains the same: what does the camera measure, and what result does the buyer accept?
The module assembly stage page lists the layup, stringing and inspection classes where vision claims appear most often.
Sources
Manufacturer specifications are source statements. Confirm configuration and acceptance conditions with the supplier. Our editorial standards