EVA Sheet: An Important Constituent of a Solar Module; Explained

Apart from solar cells, a solar module consists of many components protecting or prolonging the lives of the cells. A standard module consists of a Frame on outer edges, glass sheet, and Ethylene Viny Acetate (EVA) sheet above the solar cells. Cells are covered from lower side again with an EVA sheet before hard and durable Back sheet covers it for good.

Solar cells are sensitive to moisture, oxygen and weather. EVA is a component in a solar module that prevents air and moisture from reaching solar cells and degrading it. If not protected, solar cells will degrade with time and lose their ability to produce energy.

What are EVA films?

Ethylene vinyl acetate is a thermoplastic polymer that possesses good radiation transmission and low degradability to sunlight. It is used in the Photo-Voltaic(PV) industry as an encapsulation material for crystalline silicon solar cells in the manufacture of PV modules. Solar EVA films protect solar panels for long time with little loss in performance.

A Solar EVA sheet is a milky-white coloured rubbery substance. On heating, it becomes a transparent protective film, sealing and insulating the solar cells. With the help of a lamination machine, the cells are laminated between films of EVA in a vacuum, which is under compression, at temperatures of up to 150°C.

Interestingly, EVA films are not UV-resistant and, therefore, require protective front glass for the UV screening. Once laminated, the ethylene vinyl acetate sheets play an important role in preventing humidity and dirt penetrating the solar panels. An EVA sheets helps cells float between the glass and back sheet. This arrangement softens shocks and vibrations and, thus, protects the solar cells and its circuits from physical damage. In addition, it also increases the life of solar cells by preventing oxygen and other gasses from oxidizing the cell during the normal function of producing power.

EVA Properties

Several properties of the copolymer resin make it a key material for traditional solar panel lamination. These include

Durability

Quality EVA films possess excellent durability. They defend the cells even in difficult weather circumstances, such as high temperature and high humidity.

Bonding

EVA films exhibit an excellent adhesive bonding to glass, cell, and back sheet. The system is as strong as the bonding of EVA films with other constituents of a solar module.

Optical

EVA has excellent transparency. Thus, it helps to make optical transmission easy and doesn’t block too much of the sunshine from reaching the solar cells. Nowadays, several manufacturers in Asia use a transparent backing as well, giving transparency between the cells. This type of module is known as semi-transparent.

Encapsulation

In addition to aforementioned properties EVA sheets show brilliant encapsulating properties as well which makes them ideal for the use.

EVA Market

The demand for EVA sheets in solar module is naturally dependent directly on solar PV demand. Annual PV demand in 2021 was 173 GW, which generated 780,000 MT of EVA resin demand for EVA film. However, there was supply of just 730,000 MT of EVA resin in the year, a shortage of around 50,000 MT, as per one research. Hence, many in the industry believe that the supply of EVA resin will remain tight or may even run short in 2022. This may be due to its nature of longer capacity expansion time and higher manufacturing difficulty. It also forecasts that global PV demand will be 930,000 MT for EVA resin in 2022.

The year 2021 saw a peak of capacity expansion in the encapsulant film sector. Including POE encapsulant, total encapsulant capacity could reach beyond 5 billion m2 by the end of 2022, sustaining more than 500 GW of demand.

Major Players in the Industry

From the expansion plans’ point of view, First Applied Material, HIUV New Materials, and Sveck retain the top 3 positions as the largest manufacturers. Cybrid Technologies, Lushan, and Betterial Film Technologies are also intent on larger expansions. For EVA film manufacturers, the key to competitiveness lies in assuring their ability to secure materials amid tight raw material supply.

EVA resin providers have a major role to play to reach the growing demand of encapsulation sheets. Chinese EVA resin provider, Sierbang Petrochemical is currently keeping a monthly shipping volume of 15,000 MT, while also informing that it can release an additional 40,000 MT from solar-grade resin production lines. Further, Formosa Polypropylene (Ningbo) has a share of solar-grade resin supply. Other major player, Levima Advanced Materials, with 18,000 MT capacities from modified lines, expects to come online this year. Various new firms are popping up to meet the growing demands of the industry. This includes likes of BASF-YPC, Yulin Energy and Chemical, and Sinochem Quanzhou Petrochemical.

Provided that supply overseas remains unchanged, there should be 1,120,000 MT of PV encapsulant production capacities in 2022, sufficient to satisfy 890,000-930,000 MT of demand.