Best in Class, Proven Hot Spot Inspection

IRIS Hotspot image of an entire module.

IRIS is an innovative, time-resolved thermography system capable of identifying solar cells with shunt defects (hot spots) in fewer than 300 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 or as a standalone R&D machine and is used at top-tier PV companies worldwide. 

The IRIS system integrates a long wave 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.

Detail of four cells in a module being tested.

Detail of four cells in a module being tested.

A PV manufacturer with stringent RSH sorting criteria may bin a fraction of production as cells “at risk.”  Tau’s experience is that a reasonable fraction of cells rejected on low RSH can be safely used in modules.  Recapturing these cells for production results in increased cell and module revenue.  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 and strings prior to lamination.

Note:  we need to add lock-in thermography somewhere on this page.

The IRIS system can measure hot spots due to point defects and heating due to series resistance in entire modules, single cells, or module sections.