Alternative encapsulant material

This mitigation replaces the standard EVA encapsulant with another material, such as a polyolefin, an ionomer, PVB, TPU or silicone. The goal is to lower a module's susceptibility to potential induced degradation (PID). It works because sodium from the glass must travel through the encapsulant. An encapsulant with high volume resistivity slows this ion transport and lowers leakage current, and a low water vapour transmission rate keeps moisture out. Polyolefin encapsulants have no vinyl acetate, so they release no acetic acid. Reported benefits include less PID, less corrosion and less yellowing. Ionomers are usually used as a thin ion-blocking layer between the glass and the EVA, not as a full replacement. Co-extruded EVA/POE/EVA films combine EVA adhesion with the lower moisture transmission of POE. The additive formulation affects durability more than the base polymer does. High temperatures can also lower an encapsulant's resistivity. There are limits. Long-term outdoor experience with polyolefin encapsulants is still lacking. New degradation modes have been reported, including lower optical transmittance and ring patterns seen in UV fluorescence imaging. Some new encapsulants do not work well with certain backsheets, which can cause discoloration or poor adhesion. One ionomer type delaminated and corroded in the field. The materials should be tested alone and together in the full laminate under accelerated ageing before use.

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• sentence 5: support check: partial - Additive formulation having more influence than polymer resin is stated, and high temperature lowering resistivity is stated only for EVA, not encapsulants generally. -->