EVA Film VS POE Film

What is photovoltaic EVA film?
Photovoltaic cell encapsulation film (EVA) A thermoset adhesive film used in the middle of laminated glass. Due to the advantages of EVA film in adhesion, durability, optical properties, etc., it is more and more widely used in current components and various optical products.

Features:

• High transparency and high adhesion can be applied to a variety of interfaces, including glass, metal, and plastic such as PET.
• Good durability can resist high temperature, moisture, UV, and so on.
• Easy to store. Stored at room temperature, the adhesive force of EVA is not affected by humidity and absorbent film.
• Compared with PVB, it has a stronger sound insulation effect, especially high-frequency sound effects
• Low melting point, easy to flow, can be applied to a variety of glass glue processes, such as embossed glass, tempered glass, bending glass, and so on.

POE film has better aging resistance, low water vapor transmittance, and anti-PID performance, its water vapor transmittance is only about 1/8 of EVA film, and POE film will not decompose into acetic acid when it is in contact with water, which can effectively reduce PID effect. With excellent comprehensive performance, POE film is mainly used in high-efficiency photovoltaic modules such as double-glass and N-type, which can effectively improve the service life and power generation efficiency of photovoltaic modules.

In the photovoltaic field, EVA and POE performance have advantages and disadvantages, EVA's low price, easy processing, storage resistance, cross-linking speed, and glass & backplane bonding performance;
The advantages of POE mainly lie in good material performance, excellent PID resistance, high resistivity, large water vapor barrier rate, low-temperature resistance, and yellowing resistance.
The disadvantages of EVA: ethylene acetate is easy to hydrolysis in light, oxygen, hot and humid environments, producing acetic acid, corrosion of the battery surface, welding tape, etc. At the same time, it will react with Na in the glass, which can generate a large number of freely moving Na ions, resulting in power attenuation; At the same time, EVA is easy to yellow in the light and thermal environment, affecting the light transmission, resulting in the overall power loss of the component.
Disadvantages of POE: POE polarity is low, polar additives solvent precipitated to the film surface during film processing, resulting in smooth surface and easy displacement; The processing is difficult, the film lip is easy to hang material; The overall price of POE particles is more expensive than EVA.

In the next few years, the application proportion of POE particles in the film particles has an expanding trend, mainly due to the following factors:
N-type battery: the current photoelectric conversion efficiency of a P-type battery is close to the upper limit of 24.5%, and the upper limit of N-type battery conversion efficiency is higher; The doped boron-oxygen recombination of P-type cell in silicon wafer will cause the potential attenuation to be accelerated, and the N-type cell has better anti-attenuation performance when it is mixed with scale.
The PID effect of an N-type battery is more sensitive to the light surface, and the N-type component with large PID attenuation will also cause irreversible damage after the light recovery. At the same time, when an N-type battery uses a single glass package, the water vapor barrier of the backplane is poor, so choosing POE film for packaging can reduce the overall water vapor transmission rate of the component and extend the service time of the component. The promotion of N-type batteries can increase the amount of POE.
Battery power upsizing: In recent years, the power of different types of battery components has been significantly improved, the heat increase, the temperature will have a greater impact on the peak power of the battery, open circuit voltage, and other electrical properties, so the electrical performance of the packaging material requirements to be higher.
Cover glass thinning and double glass components increase: the current glass thickness is mainly <2.5mm, 2.8mm, and 3.2mm in three grades; Among them, the glass cover plate with a thickness of <2.5mm has a market share of 32%, and it is expected that the proportion will increase to about 50% by 2025, and the thinner glass will have higher and higher requirements for the performance of packaging materials, and POE has good mechanical strength and toughness.

EPE
EPE film is a multi-layer film made of POE resin and EVA resin by co-extrusion process, usually consisting of two layers of EVA and one layer of POE.
EPE film is a compromise product between performance and cost, which takes into account the good performance of POE film and the cost advantage of EVA film to a certain extent.
In the short term, the supply of POE resin is limited, and EPE film will occupy part of the market space.