Driving Green Energy: Discover Wankai's Advanced PET Resins for Solar Backsheet Base Films

The Key Role of PET Base Film in Solar Panel Backsheets

In the design of solar panel backsheets, PET base film plays a pivotal role as one of the core materials. Its unique characteristics make it indispensable for ensuring the overall durability and efficiency of the solar modules.

Key Requirements for Solar Backsheets

PET base film is a critical material in solar panel backsheet design, contributing to the durability and performance of photovoltaic (PV) modules. Its unique properties make it indispensable for ensuring long-term module efficiency under various environmental conditions.

An ideal solar backsheet must meet several key criteria: excellent barrier properties, weather resistance, and electrical insulation. However, no single material can deliver all these characteristics, which is why backsheets are typically multi-layered, often in a "sandwich" structure. The outer layer protects against environmental damage, the middle layer offers superior insulation and barrier properties, and the inner layer must bond effectively with EVA to maintain structural integrity under UV exposure.

PET Base Film: The Heart of the Middle Layer

As the core material in the middle layer, PET base film plays a crucial role in providing effective barriers against oxygen, carbon dioxide, and water vapor. Its exceptional barrier properties protect the internal components of the photovoltaic module, ensuring the long-term stability and reliability of the module. PET base film helps extend the module’s lifespan while maintaining optimal performance under harsh environmental conditions, such as high humidity and temperature fluctuations.

PET is widely regarded as an E-class insulating material, offering reliable electrical isolation that prevents current leakage and minimizes the risk of short circuits. Additionally, PET base film is odorless, tasteless, and highly resistant to oils and most chemical solvents, ensuring its functionality and stability even in harsh outdoor environments where exposure to UV radiation and extreme weather is common.

Due to its market availability, stability, and cost-effectiveness, PET base film is a key material in solar backsheet applications. Its combination of performance and affordability makes it an optimal choice for manufacturers seeking reliable, long-lasting materials for photovoltaic systems.

Superior Production Process for Photovoltaic Backsheet Film PET Resin

Wankai employs a state-of-the-art direct liquid-phase polymerization process to produce PET resins tailored for photovoltaic backsheet films. This streamlined process involves three key stages: esterification, pre-condensation, and final condensation, eliminating the need for solid-state polymerization and inorganic additives. 

The resulting PET resin exhibits an intrinsic viscosity of 0.630–0.760 dl/g, carboxyl end-group content of 5–16 mmol/kg, glycol content of 1.0–1.3%, and color values of L≥83, a: -2±2, and b: 1±2. For applications requiring one-sided reflectivity, titanium dioxide (TiO₂) is incorporated at approximately 0.285% to enhance the material's light-diffusing properties. 

Key Advantages of the Process  

The direct liquid-phase polymerization process eliminates the need for inorganic additives and solid-state polymerization, achieving excellent performance in terms of water vapor barrier properties, UV aging resistance, and humidity aging stability. This makes the PET resin highly suitable for use in photovoltaic backsheet films. The method is efficient, cost-effective, and easy to scale, while delivering consistently high-quality results in terms of light aging resistance and moisture durability. Additionally, the process is environmentally friendly and poses no health risks, making it a sustainable and safe solution.

Furthermore, Wankai's production technique overcomes the challenges commonly associated with traditional blended film production, such as material inconsistency and performance variability, by ensuring uniformity and consistency throughout the manufacturing process. 

Wankai's Advanced PET Resins for Photovoltaic Backsheet Films: WK-681 and WK-711

Wanke has pioneered the development of two high-performance PET resins, WK-681 and WK-711, utilizing an advanced proprietary production process tailored for the production of mid-layer films in photovoltaic backsheet applications.

1.PET Resin WK-681 for Durable Solar Backsheet Films

WK-681 is engineered for the production of high-performance films, particularly those used in solar backsheet applications that demand exceptional aging resistance, hydrolysis resistance, and thermal stability. 

With an intrinsic viscosity of 0.645±0.01, WK-681 ensures the creation of consistent, high-quality films that perform reliably under varying environmental conditions. This resin is ideal for long-term use, offering superior light aging and hydrolysis resistance, maintaining optimal performance over time. Its excellent processability ensures smooth manufacturing, delivering uniform material properties and stable processing results.

2.PET Resin WK-711 for High-Strength and Long-Term Stability

WK-711, with an intrinsic viscosity of 0.72±0.015, features a longer molecular chain structure that enhances its strength and durability, making it especially suitable for high-end applications in solar backsheet films. This PET resin is specifically designed for projects requiring superior strength and long-term stability, such as those exposed to extreme weather conditions, UV radiation, and fluctuating temperatures. The improved chemical stability and reduced reactivity, thanks to the lower carboxyl group content, ensure that WK-711 maintains excellent performance even in high-stress environments, making it the ideal choice for demanding solar applications.

3.Comparing WK-681 and WK-711: Tailored PET Resins for Solar Panel Durability

When comparing WK-681 and WK-711, both offer exceptional durability, but they cater to different performance needs. WK-681 is ideal for applications where high-temperature stability, aging resistance, and hydrolysis resistance are essential. It is best suited for long-term, stable applications that experience fluctuating environmental conditions. On the other hand, WK-711 excels in high-end solar projects requiring superior strength, chemical stability, and long-lasting durability. It is the preferred choice for solar applications exposed to extreme environmental conditions, offering enhanced strength and reliability over time.

Conclusion

PET base film plays a crucial role in solar panel backsheets, serving as a key component in solar power systems due to its exceptional performance and reliability. Wankai has developed two high-performance PET resins, WK-681 and WK-711, using advanced production techniques, offering ideal raw materials for solar backsheet film manufacturing. As the demand for high-quality, durable materials in the solar industry grows, PET base film will remain an essential element in the future of solar applications.