Comparison and Selection of PV Bracket Steel and Aluminum Materials

Frequently, there is a business asking whether the steel bracket is good or the aluminum bracket is good? To solve this problem, the author here briefly analyzes the advantages and disadvantages of steel and aluminum.

one. Material strength

Brackets generally use Q235B steel and aluminum alloy extruded profiles 6063 T6. The comparison of the two design strengths is shown in the following table:

Table 1: Table of Strength Comparison (N/mm2)

In terms of strength, 6063 T6 aluminum alloy is approximately 68%-69% of Q235 B steel, so steel is generally superior to aluminum alloy profiles in areas with strong winds and relatively large spans.

two. Deflection deformation

The deflection of the structure is related to the shape and dimensions of the profile (an inherent parameter of the material) and is not directly related to the strength of the material.

Table 2: Comparison of the two under the same cross section conditions

Under the same conditions, the deformation of aluminum alloy is 2.9 times that of steel, and the weight is 35% of that of steel. Under the same weight, the cost of aluminum alloy is 3 times that of steel. Therefore, in general, in areas with strong winds, large spans, and cost-related conditions, steels are superior to aluminum alloy profiles.

three. Anti-corrosion

At present, the main anti-corrosion method of the bracket steel is hot-dip galvanizing 55-80μm, aluminum alloy is anodized 5-10μm.

Aluminum alloy in the atmosphere, in the passivation zone, the surface of a layer of dense oxide film, hinder the active aluminum substrate surface and the surrounding atmosphere contact, it has a very good corrosion resistance, and the corrosion rate over time And decrease.

Steel under normal conditions (C1-C4 environment), 80μm galvanized thickness can be used for more than 20 years, but in the high-humidity industrial zone or high-salinity seashore and even in temperate seawater, the corrosion rate is accelerated, and the amount of galvanizing needs to be 100μm. Above and need regular maintenance every year.

Aluminum alloys are far superior to steel in terms of corrosion protection.

Fourth, other aspects

(1) Appearance: There are many kinds of surface treatment methods for aluminum alloy profiles, such as anodizing, chemical polishing, fluorocarbon spraying, electrophoretic painting and so on. Beautiful appearance and can adapt to a variety of strong corrosive environment.

Steel is generally hot-dip galvanized, sprayed, painted and coated. Appearance worse than aluminum alloy. It is also inferior to aluminum profiles in terms of corrosion protection.

(2) Cross-section diversity: The general processing methods of aluminum alloy extrusions include extrusion, casting, bending and stamping. Extrusion production is currently the main production method. By opening the extrusion die, any arbitrary section profile can be produced and the production speed is faster.

Steel is generally rolled, cast, bent, stamped, etc. Rolling is currently the main production method for the production of cold-formed steel. The cross section needs to be adjusted by the roller wheel set, but the general machine can only produce the same type of products after the shaping, the size adjustment, and the cross-sectional shape can not be changed, such as C section steel, Z section and other sections. The roller pressure production method is relatively fixed, and the production speed is relatively fast.

Fifth, comprehensive performance comparison

(1)Aluminum alloy profiles are light in weight, attractive in appearance and excellent in corrosion resistance. They are generally used in rooftop power stations and strong corrosive environments where load-bearing requirements are required. For example, Baowei color steel plate systems and chemical plant power stations use aluminum alloy as the support. There will be better results.

(2) Steel has high strength and small deflection when subjected to load. It is generally used for power plants under normal conditions or for components with large stress.

(3) Cost: In general, the basic air pressure is 0.6kN/m2, and the span is less than 2m. The cost of aluminum alloy stents is 1.3-1.5 times that of steel stents. In the small-span system, the cost difference between the aluminum alloy bracket and the steel structure bracket (such as the color steel plate roof) is relatively small, and the aluminum alloy is lighter than the steel bracket in terms of weight, so it is very suitable for a roof power station.

In the areas with large winds and relatively large span requirements, the use of steel brackets has obvious economic benefits.