CIGS’ Achilles Heel: Lifetimes and Encapsulation

Published: January 10, 2012    Category: Advanced Materials Renewable Energy

Lifetime and encapsulation are two factors that have slowed adoption of CIGS. These issues are now largely closed from a technology perspective, but remain open from a cost perspective:

• CIGS encapsulation is following much the same path as a-Si encapsulation, which encountered issues in the early 1980’s as that technology was being developed. 

• Because CIGS is much more moisture sensitive than a-Si, the techniques that proved viable for a-Si do not provide the long-term reliability needed for acceptable module lifetimes.  Much like the experience with a-Si, where early reliability failures created a poor reputation that took several years to get beyond, early reliability failures of CIGS have created a similar situation today. 

Rigid modules with glass encapsulation or glass with a metallic back and improved edge sealants now routinely pass all reliability testing.  There is still work ongoing to put flexible encapsulation systems in place that can provide greater than 20-year lifetimes, but at a cost point that keeps the technology competitive.   Current dyadic systems, which incorporate two or more alternating layers of polymer and thin ceramic, have shown promise but are expensive. 

Firms such as Dow, Fujifilm, DuPont, and 3M are actively working to improve the available encapsulation solutions.  While a lifetime of 20 years or more is a requirement for BIPV, a lower standard will be acceptable for cost-sensitive consumer products such as cell phone chargers and bags/clothing with integrated solar battery charging features.

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