In the industry, inadequate backplane insulation has long been a source of worry. One of the things that causes backplane cracking is the contact between the encapsulating material and the backplane. Which kind of film is most suited for encapsulating components? Let’s break it down together.

1. Types of PV packaging films are analyzed

In solar modules, the encapsulating adhesive film is a necessary component. It may be found on the cell’s top and bottom surfaces. Its primary purpose is to join the cell, glass, and backplate to enclose, safeguard, and expand the module. life of service. To guarantee the power generation performance of the module, the encapsulation film generally possesses high light transmittance; good adhesion to the cells and glass to ensure that the module won’t have issues such module delamination during outdoor usage; and a reasonably high With a specified strength to guarantee that it serves as a structural support throughout the module installation process, the high water vapor barrier makes sure that water vapor cannot readily enter the module and disrupt its battery circuit.

The primary material used in the manufacturing of solar film is typically resin (EVA, POE). Melt extrusion and salivation are used to create a film, then light stabilizers, thickeners, cross-linking agents, and antioxidants are added to get the final result.

The three most common adhesive film kinds available today are EVA, POE, and EPE.

Vinyl acetate with ethylene form a copolymer known as EVA. Packaging sheets for photovoltaic cells may be made from EVA resin with a VA mass fraction of 28% to 33%. Excellent light transmittance is displayed by this thick, soft cross-linked packaging film, which also serves to shield delicate silicon wafer solar cells.

POE is an ethylene-α olefin copolymer. A form of monoolefin with a double bond at the end of its molecular chain is referred to as an α olefin. POE is produced using it. primarily C8 and C4 in photovoltaic power output. POE resin, the main component of POE film, is not highly localized. The manufacturing capacity of POE is mostly concentrated in Dow, Mitsui, LG, and other companies due to significant technological hurdles in polymerization processes, metallocene catalysts, a-olefins, and other connection points. China has not yet succeeded in using POE on a wide scale in the industrial sector, but a few enterprises are trying.

EPE film is created by co-extrusion of EVA, POE, and EVA, forming a three-layer composite structure film. It not only takes into account the strong water resistance and high PID resistance of POE film, but also has the high yield of double-glass components of EVA film. The common solution for P-type double glass packaging at the moment is the features of the lamination process.

POE molecular structure

EVA molecular structure

2. Examining the differences in performance between various PV packaging films

The choice of packaging film is essential for guaranteeing the component packaging’s dependability requirements. PID resistance, electrical characteristics, and water vapor barrier characteristics of various packaging films vary because of variations in molecular structure and design.

1)The influence of variations in molecular structure

The copolymer of vinyl acetate and ethylene is called EVA film. The film exhibits good adhesion, processing properties, and high fat solubility. During component lamination, bubbles are difficult to produce. However, because of the ester group in the molecular properties, it is readily hydrolyzed to generate acetic acid during age, which results in the PID phenomenon.

2)Variations in the transmission rates of water vapor

When modules are operated outside, moisture from the surrounding air will seep into the module, oxidizing the surface grid lines on the cells and corroding the solder ribbons. These effects could lead to material degradation or even module failure. Consequently, the more dependable the module packaging, the lower the water resistance value of the packing material. The higher the sex.

POE is the least permeable to water. The analytical explanation is that traditional POE lacks polar groups and is derived from metallocene catalysts, which provide superior water vapor barrier properties. Water vapor molecules find it challenging to pierce the thick molecular structure of cross-linked POE. It has polar groups in EVA itself, and it is translucent. Following cross-linking, there is little water blocking ability, the molecular structure is rather flexible, and water molecules may pass through more readily.

3)Variations in resistivity at volume

One of the most crucial metrics for solar module performance is electrical insulation, and volume resistivity is used to measure how well the encapsulating layer is insulated. The resistance of a unit volume to electric current is known as volume resistivity, and it is used to describe a material’s electrical characteristics. Typically, the loudness The material’s effectiveness as an electrically insulating component increases with its resistance.

When it comes to volume resistivity, POE has the greatest value while EVA has the lowest. The greater the film’s volume resistivity, the more successfully the PID phenomenon of the module can be reduced, enhancing the module’s safety and dependability.

Disparities in the anti-PID capabilities of various adhesive films

The anti-PID performance of the double POE film module is the best, while the anti-PID performance of the double EVA film module is the worst. POD’s superior PID resistance, low water permeability, and high volume resistivity are the primary causes.

3.Requirements for N type cell packaging solutions

Since P-type cells’ power generation efficiency is nearly at the theoretical limit, cell technology is continuously upgraded through iteration to achieve greater conversion efficiencies.

N-type batteries are thinner, less resistant to acid corrosion, and more susceptible to water vapor than conventional P-type batteries. Consequently, N-type cells have stricter packaging specifications for the adhesive film, including the necessity that it not be able to release acetate ions. Higher water vapor barrier and better stress needs. At the moment, the industry will prioritize POE films with higher reliability for packaging in order to guarantee the dependability of N-type components.

However, no matter whatever technique is chosen, it should be remembered that in order to boost the success rate of solar packaging film packaging, we must use appropriate photovoltaic packaging film additives. The yield of photovoltaic panels is significantly influenced by the adhesion between the solar silicon crystal panel and the photovoltaic packaging film. Adding chemicals to solar packaging films is a crucial step in achieving this adherence. The yield will increase when additives are used because the film’s and the solar silicon crystal panel’s adhesion will be more effective.

Dedicated to the research and development, manufacturing, and servicing of solar packaging film additives, COACES boasts an R&D team headed by many senior engineers and physicians. The majority of consumers use COACES solar packaging film additives because of their high resistivity, good fluidity, low crystal point, high grafting rate, and high transparency!