Under CopyrightOreski, GernotGernotOreskiBaretta, ChiaraChiaraBarettaGebhardt, PaulPaulGebhardtWeiß, Karl-AndersKarl-AndersWeißMiller, David CDavid CMillerUlica, SonaSonaUlicaKempe, MichaelMichaelKempeBruckmann, Laura S.Laura S.BruckmannGnocci, LucaLucaGnocciLi, HengyuHengyuLiHabersberger, BrianBrianHabersbergerProost, KristofKristofProostKühne, MarcelMarcelKühne2024-07-312024-07-312023Note-ID: 0000829Ahttps://publica.fraunhofer.de/handle/publica/472290https://doi.org/10.24406/publica-348210.24406/publica-3482The development of new ethylene copolymer-based materials, especially, has driven the interest towards the replacement of poly(ethylene-co-vinyl acetate) (EVA). Various types of next-generation encapsulation films have been introduced in the last year under the label "polyolefin encapsulants" that could attract significant market share. These material innovations tend to be classified as cross-linked polyolefin elastomer (POE) and thermoplastic polyolefin (TPO) encapsulants. The new materials do not contain vinyl acetate moieties, consequently do not produce acetic acid upon degradation and therefore removing PV degradation mainly associated with acetic acid. Unfortunately, the terms POE or TPO are used in manner that implies that all POE or TPO encapsulants are the same. Additionally, the term "polyolefin" is understood differently in the PV industry. Elsewhere, a polyolefin is any of a class of polymers produced from a simple olefin (i.e., an alkene with the general formula CnH2n) as a monomer. That includes thermoplastic polyolefins like polyethylene and polypropylene, but also polyolefin elastomers such as polyisobutylene or ethylene propylene rubbers. The PV industry uses the term polyolefin for all non-EVA encapsulants based on polyethylene or polyethylene copolymers, which also contain other functional groups such as acrylates or acrylic acids. The main aim of the paper is to showcase the variety of recent "polyolefin" encapsulants and discuss their fundamental properties, with special focus on chemical structure, melting, and crosslinking behavior. Moreover, the influence of the base properties on PV module lamination, quality, and long-term stability will be discussed. This study resulted in a catalog of more than 40 different encapsulant films from more than 25 manufacturers. The production dates ranged from 2006 to 2022. Overall, five different base polymers were identified: (1) ethylene -olefin, (2) ethylene ethyl acrylate, (3) ethylene butyl acrylate, (4) ethylene acrylic acid, and (5) ethylene acrylic acid butyl acrylate copolymer. The melting temperatures ranged from 54 to 121°C. Most of the encapsulants need to be crosslinked like EVA, here peroxide and silane based crosslinking chemistries have been identified. Additionally, significant differences in the additive and stabilizer compositions were found. The wide variety of materials with different properties shows that the commonly used designation is too generic and that the language used must be more precise. Moreover, one encapsulant film reported in the scientific literature cannot be transferred so easily to other encapsulants with the same generic designation of "polyolefin".enconference paper