개요

Encasing and safeguarding the solar cells, photovoltaic (PV) films are essential parts of solar modules. Two materials that are frequently used for encapsulating PV films are Polyolefin Elastomer (POE) and Ethylene Vinyl Acetate (EVA). An extensive performance comparison of POE and EVA for solar films is presented in this article. Through the assessment of many attributes such as optical transparency, adhesion, moisture resistance, and long-term stability, the objective of this analysis is to illustrate the advantages and disadvantages of each material concerning solar energy applications.

Optical Transparency

Since optical transparency directly affects the amount of light transferred to the solar cells, it is an important component of PV films. Because of its superior optical clarity and strong light transmittance, EVA has long been preferred. Conversely, POE displays marginally less transparency than EVA. The difference between the two materials has decreased, nevertheless, as a result of recent developments that have produced POE formulations with better optical qualities.

Adhesion to Encapsulants and Solar Cells

To preserve the integrity of the module and stop moisture infiltration, there must be strong adhesion between the PV film and the solar cells and encapsulants. Because it is polar, EVA has a long history of good adhesion to a variety of substrates, such as glass and solar cells. With the right adhesion promoters or surface treatments, POE can achieve sufficient bonding even though it typically exhibits poorer adherence than EVA.

Resistance to Moisture

For PV modules to be reliable over the long term, moisture resistance is essential. For extended periods, EVA has proven to be a good moisture resistant material, offering a dependable barrier against the entrance of water vapour. Conversely, the moisture resistance characteristics of POE formulations can differ, and some formulations need extra moisture barrier layers to work on par with EVA.

Extended Stability

For PV films, long-term stability is crucial as during their operating life, they are subjected to a variety of environmental stresses. EVA has a strong history of dependable long-term stability and is widely utilised in the sector. It guarantees the longevity of the PV module by demonstrating outstanding resistance to UV radiation and thermal deterioration. While POE offers strong thermal stability and resistance to UV radiation, achieving the necessary long-term stability levels may require careful addition selection and formulation.

Aspects of Manufacturing

When it comes to manufacturing procedures, POE and EVA both have advantages. EVA has a long history, is extensively utilised, and has access to sophisticated equipment and processing methods. Conversely, POE presents potential benefits in terms of reduced curing periods, lower processing temperatures, and increased energy efficiency during the module manufacturing process. These elements support lower manufacturing costs and more manufacturing flexibility.

Within the realm of photovoltaics, there are distinct benefits and drawbacks associated with both EVA and POE. EVA is inexpensive, simple to produce, resistant to storing, crosses quickly, and bonds well to solar glass and backsheets. POE offers advantages in terms of anti-PID and strong material performance. Superior resistance to PID, high resistivity, elevated water vapour barrier rate, low temperature tolerance, and resistance to yellowing.

EVA 필름

The main drawbacks of EVA are that vinyl acetate is easily hydrolyzed in light, oxygen, hot, and humid environments, producing acetic acid that corrodes the solar cell’s surface as well as the ribbon copper strip. Additionally, EVA reacts with Na in the glass to produce a large number of free-moving Na ions, which reduces power. Moreover, EVA is susceptible to yellowing in photothermal environments, which reduces light transmittance and increases the PV module’s overall power loss.

POE film

POE has certain drawbacks, including low polarity, which causes polar auxiliary solvent to precipitate onto the membrane surface during adhesive film manufacturing, leaving the surface flat and easily shifted; POE particles cost more than EVA, and processing is challenging despite the film lip being simple to hang. The widespread consensus is that the following variables will mostly contribute to the expansion of POE particle application proportion in adhesive film particles over the next few years:

1. N-type battery: Currently, the P-type battery’s photoelectric conversion efficiency is almost at the upper limit of 24.5%, whereas the N-type battery’s is higher. The P-type battery’s silicon wafer doped with boron oxygen composite will accelerate potential attenuation, whereas the N-type battery with scale doping has good anti attenuation performance. The N-type battery’s PID effect is more susceptible to the light-receiving surface. Once the light returns, the N-type module with significant PID attenuation will likewise result in permanent damage. In addition, the back plate’s water vapour barrier is inadequate when the N-type battery is packaged with a single glass. As a result, using POE adhesive film for packaging can lengthen the module’s service life and lower its overall water vapour transmission rate. As a result, increasing the N-type battery’s popularity may result in a rise in POE.

2. Large-scale battery power: In recent years, there has been a notable improvement in the power of various battery module types, a rise in the calorific value, and a higher influence of temperature on the electrical characteristics of the battery, including its peak power and open circuit voltage. As a result, in recent years, packaging materials should have been subject to tougher electrical performance criteria.

The comparison of solar film performance between EVA and POE highlights several factors that module makers should take into account. EVA provides long-term stability, strong adhesion, good optical transparency, and proven moisture resistance. With the right formulation and processing, POE can perform satisfactorily even though it lags slightly in optical transparency and adhesion. It has benefits in terms of reduced processing temperatures, accelerated cure times, and possible cost reductions. Based on the particular needs of the PV module, the decision between EVA and POE should be made, taking into account aspects such optical performance, adhesion requirements, moisture resistance, long-term stability, and manufacturing issues.