ETFE film is a high-performance material for photovoltaic encapsulation, primarily applied as frontsheet encapsulation film, with prominent advantages in emerging sectors including flexible photovoltaics, Building-Integrated Photovoltaics (BIPV), and perovskite solar cells. Its core strengths lie in high light transmittance, superior weather resistance, lightweight property and self-cleaning capacity, yet it also faces drawbacks such as poor adhesion, high cost and weak scratch resistance. A systematic comparison and in-depth analysis are provided below:
Long-term light transmittance stability: Transmittance attenuation ≤5% over 20 years; conventional plastic films see ≥10% attenuation in 5 years and ≥15% attenuation in 3 years. Optical merits: Zero yellowing, uniform full-spectrum light transmission, boosting power generation efficiency by 5–8%. Glass features rigid light transmission and decent anti-aging performance yet heavy weight; PET is prone to yellowing with poor water vapor barrier; ordinary plastic films degrade rapidly with sharp light transmittance drop. Core value: Full-spectrum high light transmittance maximizes photoelectric conversion. Its UV transmittance fits novel cells such as perovskite cells, and long-term stability minimizes power degradation.
Extreme environment tolerance: Operating temperature ranges from -100°C to 150°C, with short-term heat resistance above 260°C, adaptable to harsh climates including deserts and polar regions. Anti-aging performance: After 1,000 hours of xenon lamp aging, tensile strength retention ≥95% and light transmittance decline ≤5%; power degradation merely reaches 1.98% after 1,000 hours of damp-heat aging. Chemical stability: Resistant to acid, alkali, salt spray, ozone and mold, suitable for severe environments such as coastal zones and industrial polluted areas. Lifespan advantage: 25–35 years, far exceeding PET (<10 years) and PVDF (15–20 years), close to glass (50+ years), while weighing only 1% of glass.
A 200μm-thick ETFE film weighs only 1.7 kg per square meter, merely 1% of 25 kg/m² glass, cutting the overall module weight by 70–90%. Free formability: Bendable, rollable and foldable, compatible with curved buildings, vehicle roofs, RVs and other irregular structures to realize integrated BIPV design. Structural optimization: Greatly reduces building load bearing requirements, simplifies installation and shortens construction period by 50%, ideal for low-load-bearing structures including old buildings and light steel roofs.
Self-cleaning effect: Surface energy of 18–22 dyn/cm; rainwater washes away dust, slashing maintenance frequency by over 50%. Anti-fouling & anti-adhesion: Low surface energy prevents dust and snow accumulation, lowering hot spot risks and stabilizing power output. Corrosion resistance: Excellent tolerance to seawater, acid and alkali solutions, applicable to special PV projects offshore and around salt lakes.
Impact resistance: Elongation at break of 300–440%, strong hail and wind resistance, fracture-free with zero safety hazards. Insulation performance: Dielectric strength >160 kV/mm, volume resistivity >10¹⁸ Ω·cm, preventing electric leakage and module failure. Eco-friendly and recyclable: Plasticizer-free and halogen-free, recyclable, compliant with EU RoHS and other environmental standards.
Inherent limitation: Chemically inert ETFE surface delivers weak bonding strength with EVA/POE encapsulant films, easily triggering delamination and wrinkling. Dependence on extra treatments: Special surface modification (plasma treatment, corona discharge, Saint-Gobain C-treatment) is mandatory, raising process costs and complexity. Process sensitivity: Uneven surface treatment causes local poor adhesion, undermining long-term module reliability.
Physical limitation: Conventional film thickness ranges from 50 to 150 μm, weaker than tempered glass against sand impact and sharp scratches. Application constraints: Extra caution is required during installation and operation to avoid hard object contact, increasing construction costs and difficulties. Remedial solution: Additional protective layers or thickened films (100–150 μm) are required, further pushing up costs.
Barrier weakness: Higher water vapor transmission rate than glass, requiring high-barrier POE film (water vapor permeability only 1/8 of EVA). Rising system cost: POE film is pricier than EVA, lifting overall module encapsulation expenses. Design constraints: Higher requirements for encapsulation structure to guarantee complete interlayer sealing and block water vapor from corroding cells.
Material cost: Domestic ETFE film costs 85–120 RMB/m² (2026), higher than EVA (20–30 RMB/m²) and PET (30–40 RMB/m²), close to high-end POE film (78 RMB/m²); upfront module cost rises by 10–15%. Process cost: Extra procedures including surface treatment and lamination parameter optimization increase manufacturing costs and raise yield control difficulties. Supply chain risks: Fluorochemical raw materials (e.g., TFE) face volatile prices; China holds around 65% of global fluorite mineral resources, leading to unstable material pricing. Whole life cycle cost: Lower total cost over a 25-year service cycle than traditional materials, with cost advantages emerging starting from the 5th year.
