Currently, the common module auxiliary materials include PV busbar, PV Interconnector There are eight kinds of auxiliary materials, including PV busbar, PV interconnector, tempered glass, adhesive film, backsheet, aluminum alloy, silicone, and junction box.
From the cost side, the top five auxiliary materials in terms of cost are frame, glass, film, backsheet, and welding tape. The highest percentage of non-silicon cost is in the frame. The glass, adhesive film and backsheet are the core auxiliary materials of PV modules and have an important impact on the final performance of the equipment. In the next section, we will explain these auxiliary materials and their development trends.
1. Aluminum Alloy
As the name suggests, the bezel is the outer frame of the PV module. It is filled with a silicone seal after encapsulation to play the role of fixing and edge protection. Currently, the common PV module frame is an aluminum frame. Its cost in all types of modules is second only to the battery. It is the highest cost of non-silicon auxiliary materials.
The aluminum frame production threshold is low, more suppliers, and competition is very fierce.
Photovoltaic glass is generally used as the encapsulation panel of PV modules. The glass is in direct contact with the external environment. Its weather resistance, strength, light transmission, and other indicators play a central role in the lifetime and long-term power generation efficiency of PV modules.
There are currently three main product forms of photovoltaic glass:
①Ultra-white embossed glass
②Ultra-white processed float glass
③ Transparent conductive oxide coated (TCO) glass
The development of photovoltaic glass is mainly driven upstream and downstream. The current main trends are increasing and thinning respectively.
The increase in size is mainly influenced by the upstream. Due to the gradual growth of silicon wafer size, the glass panel as a packaging panel must also increase in parallel to meet the upstream demand.
Thinning: one is the need to reduce costs, and the second is also related to the design of photovoltaic modules. At present, some bifacial modules take the double glass route with glass encapsulation on both sides. Both front and back sides use 2.5/2.0mm thickness glass, rather than the traditional 3.2mm. this is both for the overall weight reduction of the equipment, but also for cost considerations. Considering the continued growth of bifacial module penetration, the future of photovoltaic glass thinning will also continue.
3. Adhesive film
The encapsulation film is generally made of organic polymer resin. The film is in direct contact with the cell inside the module, covering the upper and lower sides of the cell. It protects the cell against water vapor and UV light.
There are three kinds of mainstream adhesive films in the market at present:
①Transparent EVA film
②White EVA film to
The development of encapsulation films is also influenced by downstream PV module design. Although the two EVA films are still the mainstream, with a combined market share of nearly 80%. However, its performance is gradually lagging behind the downstream demand, and it cannot solve the PID problem well. Therefore, it is not suitable for application on bifacial modules and is giving up market share.
PID effect is also known as potential-induced decay. It is the phenomenon of module performance degradation caused by ion migration under the action of high voltage between the encapsulation material of the module and its upper and lower surface materials, the cell and its grounded metal frame. This has a significant negative impact on the service life and conversion efficiency of PV cells.
On the contrary, POE adhesive film has a much better barrier performance. It is particularly suitable for application in water vapor sensitive technology routes, which is one of the culprits of PID effect. Therefore, with the change of downstream demand, POE adhesive film is regarded as an upgraded alternative to EVA material. Its penetration rate is rapidly increasing, and its market share has reached 25.5% in 2020, and it is expected to further increase in the future.
The backsheet is located in the outermost layer of the back of the solar module. It protects the module from the erosion of the external environment and plays the role of weatherproof insulation. Therefore, it needs to have a high level of resistance to high and low temperatures, UV radiation, environmental aging and water vapor barrier, electrical insulation and other properties.
Currently, the PV backsheet products on the market are extremely mixed, and the lack of a unified naming standard. The industry is usually divided into two categories according to whether it contains fluorine / non-fluorine and is further subdivided according to the processing technology. In order to reduce the reader’s reading burden, here no longer do specific explanations of different processes.
Along with the rapid growth in the market size of bifacial modules, the market share of glass backsheet and transparent organic material backsheet, which are included in the production due to their ability to transmit light, is rising rapidly.
5. PV RIBBON
PV ribbon is also known as tinned copper tape. It refers to a type of solder that is coated with a uniform thickness of tin base on the surface of copper tape. It is used for the connection between the cells of photovoltaic modules and plays the role of a conductive polygraph.
The PV ribbon market is fully competitive and has little bargaining power.
PV ribbon is an important raw material in the process of PV module welding. The quality of PV ribbon will directly affect the efficiency of the PV module’s current collection. And it has a great impact on the power of the PV module.
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