Making the Invisible Visible: New Luminescence Lumins · Making the Invisible Visible: New Luminescence

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  • No. 383, September 25th, 2012

    Nicole Rffer

    +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 quality and

    lowering the production costs of crystalline silicon solar cells and

    modules is the application of high-efficiency inspection systems.

    With its state-of-the-art luminescence technology ISRA SOLAR

    VISION, a business unit of ISRA VISION AG, Darmstadt, Germany,

    breaks the limit of optical inspection: The machine vision

    specialists electroluminescence and photoluminescence

    technologies capture defects that are invisible to the human eye.

    The new YIELDMASTER product line offers the first inspection

    solution that enables PV manufacturers to avoid rejected

    products due to high false detection rates. The systems provide

    the industrys fastest and most precise luminescence inspection

    and allow manufacturers to meet increased output and 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 yield and thus

    significant competitive advantages in the highly competitive PV

    market more than enough reasons to apply the smart

    luminescence inspection technology.

    Todays 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 Rffer

    +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


    Luminescence: Have a Look inside the Solar Wafers and Cells

    Luminescence is an optical phenomenon which describes a materials

    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 % Increase of A-

    Grade Yield

    The unique new feature of ISRAs 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 Rffer

    +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 Rffer

    +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. ISRAs 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 todays highly competitive PV




    Efficient optical inspection with YIELDMASTER EL - Cell

  • No. 383, September 25th, 2012

    Nicole Rffer

    +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