No. 383, September 25th, 2012
Nicole Rüffer
+49 (6151) 948 - 192
Page 1
Breaking the limits of solar inspection
Making the Invisible Visible: New Luminescence Inspection Technology for PV Production
One of the most effective ways of increasing the qu ality and
lowering the production costs of crystalline silico n solar cells and
modules is the application of high-efficiency inspe ction systems.
With its state-of-the-art luminescence technology I SRA SOLAR
VISION, a business unit of ISRA VISION AG, Darmstad t, Germany,
breaks the limit of optical inspection: The machine vision
specialist’s electroluminescence and photoluminesce nce
technologies capture defects that are invisible to the human eye.
The new YIELDMASTER product line offers the first i nspection
solution that enables PV manufacturers to avoid rej ected
products due to high false detection rates. The sys tems provide
the industry’s fastest and most precise luminescenc e inspection
and allow manufacturers to meet increased output an d quality
goals. By means of applying the new SOLARSCAN-
YIELDMASTER PL they benefit from reduced production costs, an
up to three percent increase in maximum-quality yie ld and thus
significant competitive advantages in the highly co mpetitive PV
market – more than enough reasons to apply the smar t
luminescence inspection technology.
Today’s challenges in photovoltaic production are efficiency
optimization and reduction of manufacturing costs. Especially
luminescence-based inspection methods such as Electroluminescence
(EL) and Photoluminescence (PL) open up new dimensions of quality
No. 383, September 25th, 2012
Nicole Rüffer
+49 (6151) 948 - 192
Page 2
assurance in the industrial PV production. In combination with the new
imaging technology YIELDMASTER, the luminescence inspection is
the fastest and most precise solution to capture damages in Si wafers,
cells and modules that are invisible to the human eye. They would
otherwise stay undetected during the manufacturing process and
cause high rejections and material losses or faster degration of the
modules.
Luminescence: Have a Look inside the Solar Wafers a nd Cells
Luminescence is an optical phenomenon which describes a material’s
emittance of light in the near-infrared range (NIR) when excited with
voltage (EL) or light (PL). This wavelength range is invisible to the
human eye and thus cannot be captured by standard visual inspection.
The irradiation can only be detected by highly sensitive NIR cameras
and analyzed with special image-processing software. The resulting
luminescence image enables a “look into the cell”: It reveals micro-
cracks, fractures, inhomogeneity, inactive areas and finger
interruptions. The innovative YIELDMASTER imaging technology
creates best images and thus provides a previously unattainable level
of accuracy.
High-Speed High-Accuracy Inspection for a 3 % Incre ase of A-
Grade Yield
The unique new feature of ISRA’s luminescence inspection is an
accuracy that has not been achieved by any other inspection system
so far. Its imaging process precisely distinguishes between “real”
defects that reduce the module performance and “false” defects such
as grain boundaries and impurities in the polycrystalline silicon. Only if
“real” defects are detected, the cells are downgraded. The inspection
No. 383, September 25th, 2012
Nicole Rüffer
+49 (6151) 948 - 192
Page 3
technology reduces the false detection rate by more than a factor of six
to under 0.5 percent. Consequently, manufacturers benefit from a
direct increase of higher quality yield because less immaculate
modules are sorted out as unusable. In the PV string production the
luminescence inspection allows the identification of process problems
right after they have occurred, enabling manufacturers to react
immediately. This way, defective cells can even be fixed instead of
discarding the complete string. The results are: a reduced material loss
by a factor of six and an increase of maximum-quality yield by up to
three percent.
For solar modules, ISRA offers the fastest EL inspection at triple speed
with the highest defect classification accuracy and the lowest false
detection rates resulting in the avoidance of defective or
underperforming modules. This way, the state-of-the-art luminescence
inspection enables manufacturers to achieve higher quality and lower
production losses which result in an increased efficiency in Si solar
module production. The luminescence inspection with YIELDMASTER
can be used for quality control before and after the lamination process.
The technology can easily be adapted to multiple specifications and be
implemented at many stages within the manufacturing process,
starting with the inspection of Si wafers and ending with the lifetime
estimation of Si modules.
Luminescence Inspection Leads to Higher Production Efficiency
and Guarantees Competitive Advantages
PV manufacturers are continuously looking for possibilities to offer
higher-quality products and to reduce manufacturing costs. The most
effective means to achieve these goals are innovative inspection tools.
The imaging technology YIELDMASTER, PL and EL inspection
No. 383, September 25th, 2012
Nicole Rüffer
+49 (6151) 948 - 192
Page 4
provides the most accurate and lowest false defect detection and
therefore lowest false downgrading rates. The new systems allow PV
manufacturers to control, document and increase their product quality.
They benefit from a significant reduction of the production of defective
or underperforming modules, leading to remarkable cost savings
through the reduction of material losses. ISRA’s state-of-the-art
inspection technologies offer companies in the solar industry the
possibility to detect and sort out only those products that are actually
defective. This increases quality and yield by up to three percent while
lowering costs – essential advantages in today’s highly competitive PV
market.
Images
383_1.jpeg
Efficient optical inspection with YIELDMASTER EL - Cell
No. 383, September 25th, 2012
Nicole Rüffer
+49 (6151) 948 - 192
Page 5
383_2.jpg Electroluminescence image after false color analysis for module
383_3.jpg Photoluminescence image after false color analysis of a mono cell
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