The demand for photovoltaics is booming, and the PV POE film industry, a new material for photovoltaic films, is ushering in huge opportunities.
1. What is PV POE film?
PV POE film is a kind of packaging film for the core auxiliary material of photovoltaic module. In addition, common packaging films include EVA film and EPE film. Photovoltaic adhesive film packaging materials are integrated between the cover glass/back sheet and the intermediate cells. The main function is to protect the solar cells, so that the photovoltaic modules will not be affected by external links during operation, and prolong the service life of photovoltaic modules.
At the same time, the sunlight can penetrate the adhesive film to reach the surface of the battery sheet to the maximum extent, and improve the power generation efficiency of photovoltaic modules. Therefore, the photovoltaic packaging adhesive film is required to have high light transmittance, anti-ultraviolet heat and yellowing resistance, and good adhesion to glass and backplane. At present, the mainstream photovoltaic packaging materials are EVA film, PV POE film and EPE film. The film accounts for about 4-6% of the module cost. The proportion is not high, but it has a significant impact on the service life and power generation efficiency of the module.
Moreover, compared with EVA film, PV POE film has better performance in many aspects:
- First of all, in terms of volume resistivity, as the working temperature increases, the volume resistivity of EVA film decreases rapidly, and the volume resistivity of PV POE film is 1-2 orders of magnitude higher than that of EVA film at high temperature;
- Secondly, in terms of water vapor transmission rate, PV POE film is a non-polar material, which cannot form hydrogen bonds with water molecules, and will not absorb water vapor like EVA, and the water vapor transmission rate is one-tenth of EVA material;
- At the same time, in terms of anti-ultraviolet damp heat yellowing, due to the saturated structure of the macromolecular chain of PV POE film, the molecular structure contains relatively few tertiary carbon atoms, which has better heat aging resistance and anti-ultraviolet performance.
2. Why does this node mention PV POE film?
EVA is the mainstream material for photovoltaic packaging film in the PERC era, and the most mature film material in the past. Although PV POE film has obvious performance advantages compared with EVA, in terms of actual market share, EVA still occupies the absolute mainstream, and the most direct factor limiting the penetration rate of PV POE film is that the price of PV POE film particles was higher than that of EVA most of the time. In the component packaging market in 2021, EVA will still account for more than 70%. However, whether it is the increase in the market share of bifacial modules or the iteration of photovoltaics to N-type cells, higher requirements are placed on the performance of corneal materials.
Under this background, PV POE film is vying for the leading position. In recent years, the penetration rate of bifacial modules has continued to increase. According to CPIA data, in 2021, downstream applications will further increase their recognition of the power generation gain of bifacial power generation modules. At the same time, affected by the US tariff exemption for bifacial modules, the market share of bifacial modules has increased from 29.70% to 37.40%. It is expected that the market share of single-sided and double-sided modules will be equal in 2023. In the future, bifacial modules will surpass single-sided modules and become the mainstream.
For environmental protection and cost considerations, bifacial modules usually use glass backsheets, which are more resistant to water vapor and corrosion than ordinary backsheets used in single-sided modules. However, the acetic acid decomposed by EVA cannot seep out through the back sheet and is more likely to accumulate inside the photovoltaic module, which eventually leads to corrosion of the battery sheet and attenuation of the efficiency of the photovoltaic module. At the same time, the front side of the double-sided PERC cell is chemical passivation, and its silicon nitride contains high-density fixed positive charges, which have a certain repulsion effect on Na+, while the back side is field passivation.
The Al2O3/Si contact surface has a high fixed negative charge density, and the Na+ precipitated by acetate in the glass backplane redistributes the charge in the alumina, resulting in deterioration of the passivation effect, which in turn reduces the efficiency of the module. Since PV POE film does not contain acetate, it is more suitable for double-sided module packaging. Currently, double-sided modules are usually packaged with PV POE film or co-extruded PV POE film. At the same time, the N-type battery of the next-generation mainstream technology also needs PV POE film.
According to CPIA data, the average conversion efficiency of monocrystalline PERC cells in mass production will exceed 23% in 2021, which is already very close to its efficiency limit of 24.5%. At the same time, the cost reduction rate is slowing down, and new cell technologies are developing rapidly. CPIA expects that the conversion efficiency of TOPCon, HJT and IBC batteries will exceed 25% in 2025, and the actual efficiency will increase or be faster, further widening the gap with PERC batteries. In the future, N-type batteries are expected to replace P-type batteries and become the next-generation mainstream technology.
Type N also puts forward higher requirements for the encapsulation film:
- First of all, the silver paste for N-type batteries contains aluminum, which requires higher water resistance of the adhesive film;
- Secondly, N-type batteries have higher requirements for lightweight;
- In addition, the PN junction of N-type batteries is opposite to that of P-type batteries. PID is more likely to occur on the front side, and the requirements for anti-PID performance of the film are higher. PV POE film perfectly meets the needs of N-type batteries.
What is the future industry space of PV POE film?
At present, the industry's N-type production expansion is accelerating. Among them, TOPCon batteries will be the first to be popularized and applied on a large scale because they are compatible with PERC production lines. Based on the process of PERC battery, TOPCon battery changes the original PN junction prepared by phosphorus diffusion to the PN junction prepared by boron diffusion. A layer of ultra-thin silicon oxide is added on the back of the battery, and a thin layer of doped polysilicon is deposited to form a passivation structure. Other processes are basically the same as PERC.
Therefore, the newer PERC production line can be transformed into a TOPCon production line by adding corresponding equipment to achieve technological upgrades. Due to its high compatibility, TOPCon is more likely to be favored by photovoltaic battery companies in the world, and its mass production progress is faster than other N-type batteries. According to PVinfoLink statistics, as of September 2022, the announced TOPCon production capacity has exceeded 350GW, of which the TOPCon production capacity that has already landed exceeds 40GW. It is estimated that by the end of 2022, the nominal production capacity of TOPCon will exceed 70GW.
In 2025, the production capacity of TOPCon and HJT is expected to reach 260GW and 90GW respectively. The market share of N-type technology routes such as TOPCon, HJT and XBC will increase to 37%, 7% and 7% by 2025. Using EVA+POE packaging as the assumption, it is estimated that the market share of various types of film in 2025 will be 53.88%, 22.46%, and 23.36%. From 2022 to 2025, the corresponding demand for PV POE film will be 6.43, 12.58, 1.830, and 2.444 billion square meters respectively, and the compound growth rate of demand will be 56.04%.
The demand corresponding to PV POE film particles is 21.19, 41.42, 601,600, and 806,600 tons respectively, and the compound growth rate of demand is 56.15%. In 2022, the prices of EVA and PV POE film particles once appeared upside down, and the economic disadvantage of PV POE film is weak. In the next 1-2 years, on the one hand, with the gradual adjustment of the price of silicon materials, the start-up of ground power stations may further strengthen the trend of double glass, thereby driving the demand for PV POE film. On the other hand, the large-scale industrialization of N-type directly drives up the penetration rate of PV POE film.