Advantages and Disadvantages of Steel and Aluminum for Solar Photovoltaic (PV) Mounting Structures

① Strength Comparison (Steel vs. Aluminum)

Solar PV mounting structures typically use Q235B steel and 6065-T5 extruded aluminum profiles.
In terms of strength, the strength of 6065-T5 aluminum alloy is approximately 68%-69% that of Q235B steel.
Therefore, in scenarios such as high-wind areas or large-span installations, steel outperforms aluminum alloy profiles for solar PV mounting structures.

② Deflection Deformation

Under the same conditions:

The deformation of aluminum alloy profiles is 2.9 times that of steel.
The weight of aluminum alloy is only 35% of steel.
In terms of cost, aluminum is 3 times more expensive than steel per unit weight.

Thus, steel is superior to aluminum alloy profiles for solar PV mounts in conditions such as high-wind areas, large-span requirements, and cost-sensitive projects.

③ Anti-Corrosion Performance

Aluminum alloy: In a standard atmospheric environment, aluminum alloy stays in the passive region.
A dense oxide film forms on its surface, preventing the active aluminum substrate from contacting the surrounding atmosphere.This gives it excellent corrosion resistance, and the corrosion rate decreases over time.

Steel: In a standard environment, a galvanized layer of 80μm can ensure a service life of over 20 years.
However, in high-humidity industrial zones, high-salinity coastal areas, or even temperate seawater, the corrosion rate accelerates.For such environments, the galvanized layer typically needs to be at least 100μm thick, and regular annual maintenance is required.

④ Surface Treatment Comparison

Aluminum alloy profiles: Various surface treatment methods are available, such as anodization and chemical polishing.
These treatments not only enhance aesthetic appeal but also enable the profiles to withstand various highly corrosive environments.

Steel: Common surface treatments include hot-dip galvanizing, surface spraying, and paint coating.
Compared with aluminum alloy, steel has inferior appearance and lower corrosion resistance after treatment.

Comprehensive Comparison

Aluminum alloy is lightweight and has strong corrosion resistance.
It is more suitable for mounting structures in projects such as roof-mounted PV systems (where load-bearing capacity is a concern), highly corrosive environments, or PV systems in chemical plants.

Steel has high strength and minimal deflection deformation under load.
It is generally used for components that bear large loads, making it ideal for large-scale PV power stations with high wind loads or large-span requirements.

In summary:

For small-scale projects, aluminum is mostly recommended due to its ease of installation.
For large-scale PV power station projects, steel is recommended, as it allows for high customization based on specific project requirements.