Advancements in PV cell technology, particularly those aimed at higher performance and efficiency, must be matched by long-term reliability and durability when the cells are integrated into PV modules for field operation. Likewise, back-contact (BC) technology, featuring both positive and negative metallization contacts shifted to the rear side of the cell, increases the module’s front-side efficiency, while the rear side becomes more complex and sensitive to environmental stressors.  

In response to the BC cell characteristics, Betterial, the Jiangsu, China-based producer of polymeric film materials, has recently developed a wide range of encapsulation solutions, targeting the module’s long-term reliability. The company is showcasing these latest offerings, including BC Ultra-Barrier Film, Betterial Highly Reflective Black Encapsulation Film, Highly Reflective Black Backsheet, and Westdon BC Insulating Adhesive, during the SNEC 2025 exhibition.  

These latest PV materials can be classified based on their functionalities: enhancement of reliability and performance.  

Ensuring long-term reliability 

High Barrier Film 

Unlike the conventional PV module, featuring metal contacts on both the front and rear sides of the cells, the BC variant demands advanced encapsulation materials on the rear side. To address the potential reliability risks, such as potential induced degradation (PID) and metallization corrosion, stemming from encapsulant degradation, the company developed the BC Ultra-Barrier Film. This film, featuring anti-hydrolysis technology, addresses the common degradation of EVA film, emanating from hydrolysis (reaction with water), typically in humid environments. By slowing down EVA resin aging and hydrolysis in a humid operating condition, Betterial’s proprietary Ultra-Barrier Film can extend the BC module’s operational life span, reported the company.  

Meanwhile, by incorporating ion-trapping materials that absorb or block migrating charged ions (like sodium ions), primarily responsible for PID degradation under a high negative grounded system voltage, in a humid environment, this film can reduce the BC module’s PID risk.  

Mitigating the risk of BC module metallization contact corrosion, typically caused by acetic acid formation from degraded EVA, this high-barrier film features ultra-low acid technology. According to the company, Betterial’s film produces much less acid than traditional films, thus maintaining the module’s electrical performance.  

BC Insulating Adhesive 

To prevent electrical short circuits between the BC cell’s rear side positive and negative electrodes, especially at the critical connection points between the busbars and gridlines, high-performance insulating adhesives are required. The company’s subsidiary, Westdon, has developed 2 specialized solutions to address this need: Westdon BC Rapid Thermal Cure Adhesive and BC UV Cure Adhesive. For long-term stability of high-density rear-side electrode layouts in BC modules, the adhesive should offer high adhesion strength, resistance to damp heat conditions, and long-term anti-yellowing performance. In line with this criterion, the company’s adhesive is formulated with proprietary resin technology. It features rapid curing under LED UV light for mass production, high resistance to oxygen inhibition to avoid undercuring, and reduced reliance on photoinitiators for simplified and cost-effective BC module production.  

Performance Enhancement 

Ultra-Transparent Film 

Alongside ensuring long-term reliability of BC modules, the company also developed the Betterial Ultra-Transparent EVA/EPE Film, engineered to enhance front-side optical performance. According to the company, compared to conventional encapsulation films, this solution offers an average light transmittance gain of more than 0.2% across the 380 nm and 1,100 nm wavelength spectrum. In addition, its low refractive index expands the light capture angle for the BC module, enhancing power output, noted the company.  

Betterial Highly Reflective Black Encapsulation Film 

Thanks to the demand for high-performance aesthetic BC modules, the company has developed 2 types of infrared high-reflective black encapsulation films – High-Reflective Black with and Ultra-High Reflective Black with 60% and 95% reflectivity, respectively. Leveraging special reflective pigments and fillers incorporated inside the film, the infrared light is reflected back, which would have otherwise been lost inside the module. Instead of being absorbed or escaping, this light is redirected back to the solar cells, which can boost module conversion efficiency by 2% to 4% per 100 W module, claims the company.  

The company’s representatives will be available at Booth 2.2H-E110 for technical exchange and business discussions.