Steel vs. Aluminum for PV Mounting Brackets

          In the material selection of photovoltaic supports, customers who are new to the industry often fall into the dilemma of design deviations and insufficient efficiency due to lack of professional knowledge. To help scientific decision-making, this article will deeply analyze the characteristic differences between the two main base materials, steel and aluminum, in solar installation systems and their application advantages and disadvantages.

① Steel and Aluminum Material Strength

          The mainstream materials of solar installation brackets are Q235B carbon structural steel and 6005-T5 aluminum alloy extruded profiles. In terms of mechanical strength, the tensile strength of 6005-T5 aluminum alloy is about 68% to 69% of that of Q235B steel. Therefore, in scenarios with strong wind effects and large-span structure requirements, the mechanical properties and reliability of steel brackets are more excellent compared to aluminum alloy brackets.

② Deflection Deformation

          Under the same working conditions, the plastic deformation ability of aluminum alloy is about 2.9 times that of steel, but its density is only 35% of that of steel. However, considering the economic cost, the purchase cost of the same weight of aluminum material is more than three times that of steel. In conclusion, in view of multiple considerations such as the strong wind environment, the demand for large-span structures and economy, the steel support shows a better comprehensive balance between performance and cost, and its mechanical properties and durability are significantly better than those of the aluminum alloy support.

③ Anti-Corrosion

          In the standard atmospheric environment, aluminum alloys are often in a passivated state. A dense oxide film is naturally formed on their surface. This oxide layer can effectively block the direct contact between the active aluminum matrix and the external atmospheric environment, thus endowing the alloy with excellent corrosion resistance. The corrosion rate of metals will show a decreasing trend with the passage of time.

          Under the standard meteorological environment, applying a 80 - micrometer - thick galvanized layer on the steel surface can ensure its service life of more than twenty years. But in high - humidity industrial areas, high - salinity coastal areas, and even temperate marine waters, the corrosion process will accelerate significantly. Generally speaking, the thickness of the galvanized layer should not be less than 100 micrometers, and regular maintenance should be carried out every year.

④ Surface Treatment Comparison

          Aluminum alloy profiles have rich possibilities for surface treatment, including processes such as anodizing and chemical polishing. It can not only endow them with a beautiful appearance texture but also make them adapt to harsh environments with high corrosion. In contrast, the surface protection means of steel are mostly mainly hot-dip galvanizing, spraying operations or paint coating. The appearance of this material is inferior to that of aluminum alloy, and its corrosion resistance is also slightly weak.

Comprehensive Comparison

          Aluminum materials are renowned for their lightweight characteristics and also possess excellent corrosion resistance. In scenarios such as roof power stations with load constraints, high-corrosion environments, and power stations in chemical enterprises, aluminum supports have become the preferred solution due to their comprehensive advantages.

          Steel has better mechanical strength, and the deformation (deflection) generated when bearing load is significantly reduced. Due to its excellent structural performance, this material is widely used in load-bearing key components, especially in areas with strong wind or in photovoltaic power station installation systems that need to achieve large-span support.

          In conclusion, in terms of project selection, for relatively small-scale projects, considering that their installation process is relatively simple, I usually suggest using aluminum materials. And for complex projects such as large power plants, steel is a more suitable choice because it has a high degree of customization ability and can fully meet the specific requirements of different projects.

Additional Practical Notes (for client communication):

          "The Hidden Cost Trap" in Cost Structure: The problem of aluminum is far more than the lack of a simple unit price advantage.

          The statement that "the price of aluminum is three times that of steel for the same weight" you pointed out is precise. But given that the density of aluminum (2.7 g/cm³) is significantly lower than that of steel (7.85 g/cm³), when I convert the comparison dimension from unit mass to unit length, the cost difference will be correspondingly reduced, between approximately 1.5 and 2 times. It is worth noting that aluminum brackets often need to use more costly stainless steel fasteners (to avoid galvanic corrosion), while steel brackets can use galvanized bolts. The purchase cost of these additional components sometimes causes a 30% to 40% fluctuation in the overall cost of the whole system. It is worth emphasizing again that when evaluating the system cost, the expenditure of all installation links should be included in the consideration, not only limited to the purchase price of raw materials.

2. Grounding and Electrical Conductivity Requirements

          Galvanized steel has excellent electrical conductivity. Its support system usually naturally meets the grounding specifications, and in general, only cross-connection treatment needs to be carried out.

          The surface of aluminum materials will form an insulating oxide film, and this film will hinder the flow of current. Therefore, when making ground connections, special perforated washers should be used or the oxide layer on the surface should be pre - cleared to ensure the conductivity of the ground path and the reliability of the connection. Otherwise, the project may fail to pass the acceptance due to defects in the grounding system, and this link is often ignored by new customers.