EVA and POE performance comparison

In the field of photovoltaics, EVA and POE have their own advantages and disadvantages. EVA is low in price, easy to process, resistant to storage, fast in cross-linking, and has good bonding performance with glass & backplanes; POE's advantages are mainly in good material properties and anti-PID performance. Excellent, high resistivity, high water vapor barrier rate, low temperature resistance and yellowing resistance.

The main disadvantage of EVA is that vinyl acetate is easily hydrolyzed in light, oxygen, and humid and hot environments, producing acetic acid, which corrodes the surface of the cell, the ribbon, etc., and also reacts with Na in the glass, which can generate a large amount of free movement. At the same time, EVA is prone to yellowing in the light and heat environment, which affects the light transmittance and causes the overall power loss of the module.

The disadvantage of POE is: POE has low polarity, and the polar auxiliary solvent is precipitated on the surface of the film during the film processing, resulting in a smooth surface and easy displacement; the processing difficulty is too large, and the film lip is easy to hang; the overall price of POE particles is higher than that of EVA. expensive. It is generally believed that in the next few years, the application ratio of POE particles in film particles will expand, mainly due to the following factors:

1. N-type cell: the current P-type cell photoelectric conversion efficiency is close to the upper limit of 24.5%, while the upper limit of the N-type cell conversion efficiency is higher; the doped boron-oxygen complex in the silicon wafer of the P-type cell will cause the potential decay to accelerate , N-type battery doped with scale, good anti-fading performance. The PID effect of the N-type battery is more sensitive to the light-receiving surface, and the N-type module with large PID attenuation will also cause irreversible damage after the light is restored. Therefore, choosing POE film for packaging can reduce the overall water vapor transmission rate of the module and prolong the service time of the module. Therefore, the promotion of N-type batteries can increase the amount of POE.

2. Large-scale battery power: In recent years, the power of different types of battery components has been significantly improved, the heat generation has increased, and the temperature will have a greater impact on the electrical properties of the battery such as peak power and open circuit voltage. The electrical performance requirements will be higher.

3. Thinning of cover glass and increase of double-glass components: According to CPIA data, the current glass thicknesses are mainly <2.5mm, 2.8mm, and 3.2mm; among which, the market share of cover glass with thickness <2.5mm is 32% , It is expected that the proportion will increase to about 50% by 2025. The thinning of glass will increase the performance requirements of packaging materials, and POE has good mechanical strength and toughness.

EPE film can combine the advantages of EVA and POE, and is an important development direction of film in the future. In addition, the excellent material properties of POE have huge application potential in the fields of automobiles, wires and cables, machinery, shoe sole materials, hot melt adhesives, etc. With the acceleration of the localization process, POE will cultivate a larger market space.