In the first part of this bipartite article, we mentioned that three encapsulation materials, EVA TPO and PVB, have grabbed the most share of the market. Although EVA has the bigger slice of it, it has lost its share gradually due to the entrance of the other two encapsulants and avoiding its failures. First of all, we assess and list the advantages and disadvantages of TPO and PVB as two suggested alternatives for EVA. Then, we briefly compare these two ones with the EVA and come to the conclusion which encapsulant has the greatest potential of being a suitable alternative for EVA.
EVA is prone to moisture ingression, acid acetic formation, and UV degradation. They result in several time-dependent failures in field installations . Some studies have been suggested adding peroxide as the cross-linking agent and UV absorber such as Cyasorb UV 531 to it. These ideas pursued the aims of increasing thermal stability and mitigating the UV degradation of PV modules, especially delamination and discoloration [12-14].
Non-cross-linking thermoplastic polyolefin or TPO do not need any additive to have better performance under different climate conditions comprised of hot, humid, and high doses of UV radiation [15,16]. As a result, it avoids acid acetic formation and reduces the time of the lamination process of PV modules in the production line. Like any alternative, TPO also has its own strengths and weaknesses. The adhesion of TPO to glass, cells, and backsheet is the main drawback of it .
As another proposed encapsulation material, PVB is a thermoplastic resin which is widely used for applications requiring strong binding, toughness, and flexibility. The lowest Young’s modulus of PVB provides these features. PVB is also used in glass-glass PV modules. PVB drawbacks are high glass transition temperature and water vapor transmission rate.
To sum up, TPO as a promising candidate to substitute EVA has generally met all the three pillars of the Golden triangle (price, performance, & Efficiency) while PVB has the main drawbacks of EVA. Therefore, TPO is well fitted for replacing with EVA. it is expected that TPO’s share in the market increase more than three-time over the coming decade .
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