With the rapid development of China's green economy, monocrystalline silicon/polycrystalline silicon photovoltaic power generation and thin film BIPV technology are maturing. Compared with other solar mounting structures, solar steel structures have great advantages in terms of function, design, construction and overall cost. Therefore, it is of great significance to actively develop and produce a new steel structure photovoltaic support system to replace the existing angle steel support system.
1. Steel type for solar mounting steel bracket
At present, in view of the simple solar panel mounting structure and small volume of the solar photovoltaic support, most of the selected steel materials are light structural steel and small-section ordinary steel structural steel.
Lightweight structural steel: Lightweight structural steel mainly refers to round steel, small angle steel and thin wall steel. Among them, when the angle steel is used as the support member, the strength of the steel material can be better utilized, and the installation of the integral bracket is facilitated, but when used as a bent and pressed member, the deformation is relatively large. At present, the national standard angle steel is not limited to the solar bracket, so more small angle steel models are needed to adapt to the current fast-growing solar market. The purlin member of the thin-walled steel is generally made of a thin steel plate having a wall thickness of 1.5 to 5 mm, and is formed into a thin-walled steel product of various cross-section forms and sizes after cold bending or cold rolling.
Compared with hot-rolled steel, the radius of gyration of thin-walled steel can be increased by 50-60% and the moment of inertia and resistance of the section can be increased by 0.5-3 times under the same cross-sectional area. The strength, but because the processing of thin-walled steel is mostly in the factory, it requires high-precision drilling to match the screw holes behind the photovoltaic panel. After the factory processes the drill buckle, it can be hot-dip galvanized and rust-proof; when it is transported to the site for installation, due to the small section of the steel, the tool is difficult to operate and the construction is difficult. At present, most of the domestic panels cannot be directly connected to thin-walled steel, and all other auxiliary fixing structures (such as briquetting) are required.
Ordinary steel structural steel: ordinary structural steel often adopts carbon structural steel or low alloy steel which is easy to smelt and low in cost. There are many types of cross sections. The commonly used photovoltaics mainly include I-shaped, H-shaped, L-shaped and various design requirements. Profiled section. There are also various processing methods. The welded steel is made of steel plates with different thicknesses. According to the design requirements, the steel is welded and processed in the factory. This molding method can be calculated according to the force of different structural parts of the photovoltaic engineering project. The thickness of the steel plate is more reasonable than the hot-rolled one-shot product, which is more suitable for on-site installation and can also save steel.
2, solar panel support requirements for steel properties Solar steel structure steel should have the following properties:
1) Tensile strength and yield point. The high yield point can reduce the section of the steel member, reduce the structural weight, save steel and reduce the overall project cost. High tensile strength can increase the overall safety reserve of the structure and improve the reliability of the structure.
2) Plasticity, toughness and fatigue resistance. Better plasticity can cause large deformation of the structure before it is destroyed, so that people can find and take remedial measures in time. Better plasticity can also adjust the local peak stress. The solar panel installation itself often uses forced installation for angle adjustment, and plasticity can cause internal force redistribution of the structure, so that the stress of some of the original stress concentration parts of the structure or component tends to Uniform, improve the overall bearing capacity of the structure. The better toughness can make the structure absorb more energy when it is destroyed by the external impact load. Especially for the desert power station and the roof power station with large wind power, the wind vibration effect is obvious, and the toughness of the steel can effectively reduce the dangerous degree. Better fatigue resistance also allows the structure to have a strong resistance to alternating wind loads.
3) Processing performance. Good processing properties include cold workability, hot workability and weldability. The steel used in photovoltaic steel structures is not only easy to process into various forms of structures and components, but also requires that these structures and components do not have the adverse effects of excessive strength, plasticity, toughness and fatigue resistance due to processing.
4) Service life. Since the design life of solar photovoltaic systems is more than 20 years, good corrosion resistance is also an important indicator to measure the quality of the stent system. If the life of the stent is short, it will inevitably affect the stability of the entire structure, resulting in an extended payback period and lowering the economic benefits of the entire project.
5) Under the above conditions, the steel for photovoltaic steel structure should also be easy to purchase, produce, and cheap.