How to choose the support equipment of distributed photovoltaic?
Photovoltaic bracket is a special bracket designed for placing, installing and fixing solar panels in photovoltaic power generation systems. General materials are aluminum alloy, carbon steel and stainless steel. The surface of carbon steel is hot-dip galvanized and does not rust for 30 years of outdoor use. It is characterized by no welding, no drilling, 100% adjustable, 100% reusable.
Photovoltaic bracket as an important part of photovoltaic power station, it carries the main body of photovoltaic power station. The choice of support will also directly affect the operation safety of photovoltaic modules, damage rate and construction investment, choosing the right photovoltaic support can not only reduce the project cost, but also reduce the later maintenance cost!
So, how to choose distributed photovoltaic support equipment?
1. Material strength
The support generally uses Q235B steel and aluminum alloy extrusion profile 6063T6, strength, 6063T6 aluminum alloy is about 68%-69% of Q235B steel, so generally in the strong wind area, the span is relatively large and other cases of steel is better than aluminum alloy profile.
2. Deflection deformation
The deflection deformation of the structure is related to the shape and size of the profile and the elastic modulus (an inherent parameter of the material), and is not directly related to the strength of the material.
Under the same conditions, the deformation of aluminum alloy profiles is 2.9 times that of steel, the weight is 35% of steel, and the cost is 3 times that of steel under the same weight. Therefore, generally in strong wind areas, relatively large span, cost and other conditions, steel is better than aluminum alloy profiles.
3. Chemical composition
The content of carbon, sulfur, phosphorus and other chemical elements of the selected steel structure main material must comply with the relevant provisions of “Carbon Structural Steel” (GB/T700-2007).
4. Rust removal
1) The surface treatment of steel components shall be carried out, and the rust removal method and rust removal grade shall comply with the relevant provisions of the current national standard “Corrosion grade and rust removal grade of Steel surface before painting” (GB8923-88).
2) Rust removal method: steel members can use sandblasting or shot blasting rust removal method, if the use of chemical rust removal method, should be selected with rust removal, phosphating, passivation of two or more functions of the treatment liquid, its quality should meet the current national standard “multifunctional steel surface treatment liquid general technical conditions” (GB/T 12612-2005) provisions.
3) Derusting grade: Derusting grade should meet the requirements of Sa2 1/2.
5. Corrosion protection
At present, the main anti-corrosion method of the bracket is hot-dip galvanized 55-80μm, and aluminum alloy is anodized 5-10μm.
In the atmospheric environment, aluminum alloy is in the passivation zone, and a dense oxide film is formed on its surface, which prevents the active aluminum matrix surface from contacting with the surrounding atmosphere, so it has very good corrosion resistance, and the corrosion rate decreases with the extension of time.
Steel under ordinary conditions (C1-C4 environment), 80μm galvanized thickness can guarantee the use of more than 20 years, but in high humidity industrial areas or high salinity seaside or even temperate sea water, the corrosion rate is accelerated, galvanized amount needs 100μm, above and need to be regularly maintained every year.
Aluminum alloy is far superior to steel in corrosion protection.
Other anti-corrosion comparison
1) Appearance
Aluminum alloy profiles have many surface treatment methods, such as anodic oxidation, chemical polishing, fluorocarbon spraying, electrophoretic painting and so on. Beautiful appearance and can adapt to a variety of strong corrosive environment.
Steel is generally used hot dip galvanizing, surface spraying, paint coating and other methods. Appearance worse than aluminum alloy profile. It is also worse than aluminum in terms of corrosion protection.