Tau Science IRIStm Hotspot Detection System



IRIS™ is an innovative, in-line screening tool capable of identifying solar cells with shunt defects (hot spots) in under 500 milliseconds. Customers can increase revenue and profit by discerning between cells that are safe for assembly into modules while discarding electrically similar cells that will overheat and degrade in the field. IRIS, exportable under ITAR, is designed for integration into the cell manufacturing line and is running at top-tier manufacturing sites. A stand-alone version (shown above) is also available.

The IRIS system integrates a deep infrared camera and proprietary image processing algorithms to assess the shunt characteristics of the cell under reverse bias conditions. The analysis is controlled through a user configurable recipe with control limits that disposition the cell into Pass or Fail bins in less than one second. The results of this fast, in-line measurement have been shown to correlate well with conventional lengthy cell heating measurements. Adding this unique inspection impacts the manufacturer’s top line by identifying cells that will operate within preset temperature limits and can therefore be shipped as product. It impacts the manufacturer’s bottom line by conclusively identifying cells prone to field failure that should be scrapped.

A PV manufacturer with stringent RSH sorting criteria may bin up to 5% of production as cells “at risk.” Tau’s experience is that approximately ½ of cells rejected on low RSH can be safely used in modules. Recapturing these cells for production results in $1.25M of additional annual cell revenue and $2.5M of additional module revenue per 50MW of output. Similarly, module manufacturers who are concerned with reliability guarantees and warranty reserves can increase their long-term product performance by utilizing IRIS to inspect cells prior to module assembly.

IRIS System Specifications

IRIS 110 series - Manual system

  • Infrared Camera: 8-14 micron wavelength
  • Resolution: 256x256 pixels
  • Field of View: 100, 125, 150mm [others on request]
  • Sample DC Bias: ±10 Amps, ±20 Volts
  • Recipe-driven UI: Advanced Recipe Builder, Data Review & Replay
  • Measurement Dwell Time Configurable via recipe: 100-500ms typical
  • Failure Modes Detected:
    • Excess leakage current (user-configurable limits)
    • Time-resolved hotspot analysis (transient, steady-state)
    • Configurable image analysis algorithm for Pass/Fail sort
  • Power Conditioning: Integrated Uninterruptible Power Supply
  • AC Power Input: 220VAC, 1phase, 10A, 50-60Hz
  • Safety: EMO, LOTO breaker


  • Measurement Chuck: Configurable per customer requirements
  • Configurable Data Backup: Automated data push to server or NAS
  • Yield Summary File for Host:
    • Defect location, severity, temperature
    • Pass/Fail results of hotspots & J-V test

IRIS 210 series - Automation ready system

  • Same configuration and options as IRIS 110
  • Automation-ready module with compact measurement chamber and electronics modules integrates to wafer handler via industry-standard 24VDC communications link.
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