EVA solar photovoltaic film: performance characteristics and industry application analysis

EVA (ethylene vinyl acetate copolymer) solar photovoltaic film is the core packaging material of photovoltaic modules. Its performance directly affects the power generation efficiency, service life and environmental adaptability of the module. With the continuous growth of global photovoltaic installed capacity, the EVA photovoltaic film industry is facing dual opportunities of technological upgrading and market demand.

Core characteristics of EVA photovoltaic film

1. High light transmittance and weather resistance

• The light transmittance needs to be more than 90% to ensure the light energy conversion efficiency, and it also needs to resist environmental aging (PID effect) such as ultraviolet rays and heat and humidity.

• Improve durability by adding UV absorbers and anti-aging additives (usually requiring a life span of more than 25 years).

• During the lamination process, it forms a strong bond with glass and backsheets (such as TPT, TPE) to avoid delamination or bubble defects.

• The degree of cross-linking (usually 65%-85%) directly affects the mechanical strength and heat resistance and needs to be accurately controlled by peroxide initiator (such as DCP).

Technical challenges and innovation directions

Current pain points ：

• yellowing problem : The vinyl acetate chain segment is easily degraded under long-term UV irradiation, resulting in a decrease in light transmittance.

• PID decay : Potential-induced degradation caused by sodium ion migration needs to be alleviated by high volume resistivity EVA.

• cost sensitive : The pressure of cost reduction in the photovoltaic industry is forcing the cost-effective optimization of materials.

technological breakthrough ：

• Co-extruded multi-layer structure : Composite design with UV resistance on the surface and high adhesion on the bottom layer (such as EVA/POE double-layer film).

• New anti-PID additive : Such as introducing inorganic nanoparticles such as silicon nitride.

• Rapid curing process : Reduce lamination temperature and time to improve production efficiency.

Market Trends and Green Transformation

1. N-type battery driven POE replacement ：

• N-type batteries such as TOPCon and HJT are sensitive to water vapor, and the permeability of POE (polyolefin elastomer) packaging films has increased. However, EVA still dominates the PERC market due to its cost advantage.

• The chemical dissolution method separates EVA and silicon wafers, achieving a component recovery rate of >95%.

• Domestic companies (such as Foster and Haiyou New Materials) have occupied more than 60% of the global share, and their technical indicators are comparable to overseas brands.

In the future, with the iteration of photovoltaic technology (such as the application of perovskite modules), the functional requirements of EVA films will become more stringent, and the combination of high performance and sustainability will become the core competitiveness of the industry.