Comparing the Advantages and Disadvantages of EVA and POE Solar Encapsulation Films: Why EPE Might Be the Ultimate Market Choice

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With the rapid development of the photovoltaic (PV) industry, the choice of encapsulation film materials has become increasingly critical. Currently, there are four main types of PV encapsulation films on the market: transparent EVA film, white EVA film, POE film, and co-extruded EPE film. This article explores the pros and cons of EVA and POE films and discusses why EPE films may be the ultimate choice for the future.

Advantages and Disadvantages of EVA Films

Advantages:

1. Lower Cost: EVA is relatively inexpensive, making it suitable for large-scale production and application in the PV industry.

2. Easy to Process: EVA is simple to process, with fast cross-linking speeds, ideal for mass production.

3. Excellent Adhesion: EVA provides strong adhesion to glass and back sheets, forming a reliable module structure.

4. High Light Transmittance: EVA maximizes light transmission to solar cells, enhancing power generation efficiency.

5. Good Weather Resistance: EVA has good resistance to UV rays, moisture, and temperature fluctuations, extending the module's lifespan.

6. Electrical Insulation: EVA is an excellent electrical insulator, preventing short circuits and enhancing electrical safety.

7. Readily Available Raw Materials: EVA materials are relatively easy to obtain and are primarily sourced domestically, ensuring a stable and cost-effective supply.

Disadvantages:

1. Hydrolysis: EVA can hydrolyze in light, oxygen, and humid environments, producing acetic acid that corrodes solar cells and solder ribbons.

2. Yellowing: EVA tends to yellow under light and heat, reducing light transmission and overall module efficiency.

3. Poor Thermal Stability: EVA has lower thermal stability at high temperatures, which can lead to aging, deformation, or delamination.

4. Susceptibility to Heat and Humidity: EVA can degrade in hot and humid conditions, leading to performance loss.

5. Low Breathability: EVA’s poor breathability can cause gas buildup inside the module, affecting its stability and performance.

Advantages and Disadvantages of POE Films

Advantages:

1. High Thermal Stability: POE exhibits excellent thermal stability at high temperatures, resisting thermal aging.

2. Strong Weather Resistance: POE is highly resistant to UV rays, moisture, and temperature changes, making it suitable for harsh environments.

3. Excellent PID Resistance: POE has high electrical resistivity and excellent Potential Induced Degradation (PID) resistance, ideal for high-voltage applications.

4. High Water Vapor Barrier: POE provides superior water vapor barrier properties, extending the module's lifespan.

5. Low-Temperature Resistance and Anti-Yellowing: POE performs well in low temperatures and resists yellowing effectively.

6. Electrical Insulation: Like EVA, POE is an excellent electrical insulator, ensuring electrical isolation and protection.

Disadvantages:

1. Higher Cost: POE is more expensive, increasing the manufacturing costs of PV modules.

2. Lower Light Transmittance: POE has lower light transmittance compared to EVA, which might affect power generation efficiency.

3. Processing Challenges: POE is harder to process due to its low polarity, which can cause additives to migrate to the surface and make the film slippery and prone to defects.

4. Dependence on Imported Raw Materials: Although there have been some breakthroughs in domestic production, POE raw materials still primarily rely on imports, keeping prices high.

5. Non-Public Formulas: POE formulas vary by manufacturer and are not publicly disclosed, leading to higher technical complexity and diverse formulations.

Equipment Differences

The equipment used for producing EVA and POE films also differs significantly. EVA film production lines typically use single-machine designs, which are easier to operate and more cost-effective. In contrast, POE film production requires higher electrical currents, necessitating more powerful motors and frequency converters. Additionally, the higher processing difficulty of POE demands more advanced equipment.

Dual-extrusion production lines that can produce both EVA and POE films offer greater flexibility and cost savings. These lines are designed to accommodate the unique properties of both materials, ensuring efficient production.

EPE Films: The Ultimate Market Choice

EPE films combine the strengths of both EVA and POE, representing an important direction for future development. EPE films offer the high water resistance of POE and the strong adhesion properties of EVA, making them ideal for dual-glass modules and N-type solar cells.

Advantages of EPE Films:

1. High Water Resistance: Extends module lifespan, suitable for high humidity and harsh environments.

2. Strong Adhesion: Ensures the stability and reliability of the module structure.

3. Superior Combined Properties: Combines the advantages of both EVA and POE, applicable in various scenarios.

4. Cost-Effective: Uses co-extrusion processes to optimize costs while delivering superior performance.

Market Trends and Future Prospects

Market Share

EVA Films:

1. Mainstream Choice: Currently, EVA films dominate the PV encapsulation market, holding a high market share.

2. Widespread Application: EVA films are widely used in various PV module encapsulation applications due to their excellent optical properties, strong adhesion, and low thermal shrinkage.

POE Films:

1. Dual-Glass Modules: POE films are mainly used in dual-glass module encapsulation, where both the top and bottom layers use glass, typically for PV projects with higher environmental requirements.

2. Smaller Market Share: Although POE films have excellent weather resistance and a wide temperature range, their market share is smaller compared to EVA films. This is mainly because EVA films are the mainstream choice, and POE films are more expensive and used in specific scenarios.

According to statistics, in 2022, the combined market share of POE and EPE films in China was 35.6%, up 12.5% from the previous year. This share is expected to rise to 52.1% by 2025. Although the rapid growth of TOPCon and other N-type PV installations will drive demand for POE films, EVA films will still dominate the market due to the high costs and import dependence of POE raw materials.

Conclusion

EVA and POE films each have their advantages and limitations, suitable for different applications. However, EPE films, which combine the best features of both EVA and POE, represent a crucial future development direction. As technology advances and market demands evolve, EPE films are likely to become the ultimate choice in PV encapsulation, driving sustainable growth and innovation in the PV industry.

Understanding these materials' characteristics and market dynamics helps PV manufacturers select the most appropriate materials to optimize module performance and cost, promoting industry-wide advancement.