The Upcoming Materials to Be Used in the PV Module Encapsulant – Part 2

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 [11]. 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 [17].

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 [18].

Reference

  1. López-Escalante, M. C., Luis J. Caballero, F. Martín, M. Gabás, A. Cuevas, and J. R. Ramos-Barrado. “Polyolefin as PID-resistant encapsulant material in PV modules.” Solar Energy Materials and Solar Cells 144 (2016): 691-699.
  2. Peike, Cornelia, Ingrid Hädrich, Karl-Anders Weiß, Ines Dürr, and F. Ise. “Overview of PV module encapsulation materials.” Photovoltaics International 19 (2013): 85-92.
  3. Pern, F. J., and A. W. Czanderna. “EVA degradation mechanisms simulating those in PV modules.” In AIP Conference Proceedings, vol. 268, no. 1, pp. 445-452. American Institute of Physics, 1992.
  4. Adothu, B., Bhatt, P., Zele, S., Oderkerk, J., Costa, F. R., & Mallick, S. (2020). Investigation of newly developed thermoplastic polyolefin encapsulant principle properties for the c-Si PV module application. Materials Chemistry and Physics, 243, 122660.
  5. Adothu, Baloji, Parth Bhatt, Shashwata Chattopadhyay, Sarita Zele, Jeroen Oderkerk, H. P. Sagar, Francis Reny Costa, and Sudhanshu Mallick. “Newly developed thermoplastic polyolefin encapsulant–A potential candidate for crystalline silicon photovoltaic modules encapsulation.” Solar Energy 194 (2019): 581-588.
  6. Adothu, Baloji, Sudhanshu Mallick, and Purnendu Kartikay. “Determination of Crystallinity, Composition, and Thermal stability of Ethylene Vinyl Acetate Encapsulant used for PV Module Lamination.” In 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC), pp. 0491-0494. IEEE, 2019.
  7. Oreski, Gernot, Antonia Omazic, Gabriele Christine Eder, Yuliya Voronko, Lukas Neumaier, Wolfgang Mühleisen, Christina Hirschl, Gusztáv Ujvari, Rita Ebner, and Michaell Edler. “Properties and degradation behaviour of polyolefin encapsulants for photovoltaic modules.” Progress in Photovoltaics: Research and Applications 28, no. 12 (2020): 1277-1288.
  8. Trube, J., M. Fischer, G. Erfert, C. C. Li, P. Ni, M. Woodhouse, P. Li et al. “International technology roadmap for photovoltaic (ITRPV).” VDMA photovoltaic equipement 24 (2018): 77-97.