Stabilized encapsulant formulation

A stabilized encapsulant formulation is an encapsulant whose additive package, such as a UV absorber and antioxidants, is designed to withstand photo-oxidative stress. It is a preventive measure against discoloration, meaning yellowing of the encapsulant. The encapsulant has to keep its optical, electrical and mechanical properties under UV and heat over the module's life, so low light absorbance is a key requirement. The additive formulation affects durability more than the type of base polymer resin does. Reduced yellowing has been reported for non-EVA polyolefin encapsulants, which also do not release acetic acid as they degrade. Additives can cause discoloration themselves. In damp heat testing, oxidised additives in a polyolefin encapsulant reacted with additives in a polyolefin backsheet and caused strong yellowing. Because of this, the encapsulant should be tested together with the adjacent backsheet and glass in accelerated ageing tests during product development, and compatible materials should be selected. The limit is that long-term outdoor experience with the newer polyolefin encapsulants is still lacking, and most durability data come from accelerated tests. Discoloration itself usually costs only several percent of module performance.

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• sentence 1: support check: partial - Passage says EVA formulation is adapted for photo-oxidative stress and contains UV absorber and antioxidants, but doesn't define a 'stabilized formulation' as a preventive measure against yellowing/discoloration.
• sentence 5: support check: partial - Passage supports oxidised encapsulant additives interacting with PO-backsheet additives in DH testing causing strong discoloration, but doesn't state generally that additives cause discoloration themselves beyond this case (and notes it doesn't occur in real life). -->