The frame material of the battery module is mainly made of aluminum alloy, but also stainless steel and reinforced plastics. The main functions of the battery module installation frame are as follows: the first is to protect the edge of the laminated module glass; the second is to combine the silicone rim to strengthen the sealing performance of the module; the third is to greatly improve the overall mechanical strength of the battery module; the fourth is to facilitate the transportation and installation of the battery module. Whether the battery modules are installed separately or form a photovoltaic array, they must be fixed to the battery module brackets by the frame. Generally, holes are punched in the appropriate parts of the frame, and the corresponding parts of the bracket are also punched, and then fixed and connected by bolts, or fixed by pressing on the frame of the module by a special pressing block. The outline of commonly used frame profiles and angle aluminum is shown in Figure 1.
The aluminum alloy frame material is generally 6063T6 aluminum alloy material, and its composition is shown in the table in Figure 2. The surface of the aluminum alloy material of the battery module frame is usually subjected to surface oxidation treatment. The oxidation treatment is divided into three types: anodic oxidation, sandblast oxidation and electrophoretic oxidation.
Anodizing is the electrochemical oxidation of aluminum alloy materials. It uses aluminum alloy profiles as anodes in the corresponding electrolyte (such as sulfuric acid, chromic acid, oxalic acid, etc.), and electrolysis is performed under specific conditions and applied current. The aluminum alloy of the anode is oxidized, and an aluminum oxide film layer is formed on the surface, the thickness of which is 5-20μm, and the hard anodized film can reach 6-200μm. The metal oxide film changes the surface state and performance of the aluminum alloy profile, such as changing the surface coloring, improving corrosion resistance, enhancing wear resistance and hardness, and protecting the metal surface.
Sandblasting oxidation is that aluminum alloy profiles are sandblasted, all the oxides on the surface are treated, and after sandblasting impact, the metal on the surface layer is compressed and densely arranged, and the metal crystal becomes smaller, forming a firm, dense and high hardness oxide layer on the aluminum alloy surface.
Electrophoretic oxidation is the process of plating a thin layer of other metals or alloys on the surface of aluminum alloy using the principle of electrolysis. During electroplating, the coating metal is oxidized into cations and enters the electroplating solution; the aluminum alloy product to be plated serves as the cathode, and the cations of the coating metal are reduced on the surface of the aluminum alloy to form a coating. In order to eliminate the interference of other cations and make the coating uniform and firm, it is necessary to use a solution containing the coating metal cations as the electroplating solution to keep the concentration of the coating metal cations unchanged. The purpose of electroplating is to plate a metal coating on the substrate to change the surface properties or size of the substrate. Electroplating can enhance the corrosion resistance of the metal (the coating metal is mostly corrosion-resistant metal), increase the hardness, prevent abrasion, and enhance the lubricity, heat resistance and surface aesthetics of the aluminum alloy profile.
The common specifications of aluminum alloy frame profiles are 17mm, 25mm, 30mm, 35mm, 40mm, 45mm, 50mm, etc. The appearance of some aluminum alloy frames and corner aluminum is shown in Figure 1. There are two ways to fix the four corners of the aluminum alloy frame. One is to insert tooth-shaped corner aluminum (commonly known as corner code) into the four corners of the frame, and then use a special corner striker to fix it or use an automatic framing machine combination to fix it; another method is to fix the four corners of the frame with stainless steel bolts. Figure 3 and Figure 4 are the specifications and dimensions of commonly used aluminum alloy frame profiles.
The aluminum alloy profile frame should be stored in a constant temperature and humidity warehouse. The storage temperature is 20~30℃ and the relative humidity is less than 60%. Avoid direct sunlight and wind. The maximum storage time is no more than one year.