Photovoltaic brackets are exposed to harsh outdoor environments (ultraviolet rays, rain, salt spray, etc.) for a long time. Ordinary fasteners are prone to corrosion and loosening, leading to structural safety hazards. How to select highly corrosion-resistant stainless steel fasteners to ensure the stable operation of photovoltaic systems for more than 20 years? This article provides key guidelines such as material selection, anti-loosening solutions, and installation points to help solve the fastening problems of photovoltaic brackets.
1. Core challenges of photovoltaic bracket fasteners
(1) Corrosion problems in harsh environments
Coastal areas: Salt spray accelerates metal oxidation, and ordinary carbon steel fasteners rust in 1 to 2 years.
Industrial pollution areas: Acid rain and sulfides corrode threads and reduce bite force.
Alternating high and low temperatures: Thermal expansion and contraction lead to a decrease in preload and loosening of bolts.
(2) Loosening risks caused by dynamic loads
Alternating stresses such as wind vibration and snow loads will cause ordinary bolts to gradually loosen, threatening structural safety.
(3) Installation efficiency and maintenance cost
The photovoltaic project is large in scale and requires maintenance-free design to avoid frequent maintenance.
2. Key points for selecting stainless steel anti-rust fasteners
(1) Material selection: 304 vs 316 stainless steel
A2-70 (304 stainless steel): suitable for general outdoor environment, cost-effective.
A4-80 (316 stainless steel): contains molybdenum, resistant to salt spray and chemical corrosion, suitable for coastal areas and near chemical plants.
(2) Anti-loosening design: ensure long-term stability
Double nut + spring washer: mechanical anti-loosening, suitable for high vibration areas.
Nylon locking nut (Nyloc): friction anti-loosening, easy to disassemble and assemble.
Thread glue (Loctite): fill thread gaps to prevent fretting corrosion.
(3) Surface treatment to enhance corrosion resistance
Passivation treatment: improve the protective power of the oxide film on the stainless steel surface.
Dacromet coating (optional): additional protection against extreme environments.
3. Optimization suggestions for photovoltaic bracket fastening solutions
(1) Bolt-nut combination recommendation
M8~M12 stainless steel bolts (A4-80 grade) + flange nuts to reduce contact surface corrosion.
Embedded anchor bolts: Concrete foundation rust prevention is more durable.
(2) Key points of installation process
Torque control: Use a torque wrench to avoid over-tightening and stress corrosion.
Avoid contact between dissimilar metals: Direct contact between stainless steel and aluminum brackets may cause galvanic corrosion, and insulating gaskets need to be added.
(3) Regular inspection and maintenance
Check whether key node bolts (such as diagonal braces and base connections) are loose every year.
Bolts that are severely corroded need to be replaced as a whole to avoid local repairs.
4. Frequently Asked Questions (Q&A)
Q: Will stainless steel bolts never rust?
A: In chloride ion (such as coastal areas) or acidic environments, 304 may still be pitted, so 316 is preferred.
Q: Can galvanized bolts be used instead of stainless steel?
A: Corrosion accelerates after the galvanized layer is damaged. It is recommended to use stainless steel directly for photovoltaic projects.
Q: How to reduce the procurement cost of fasteners?
A: 304 stainless steel can be used for non-critical parts (such as internal connections of the bracket), and 316 for critical parts (such as exposed nodes).
Summary
The fastening problem of photovoltaic brackets needs to be solved from three aspects: material corrosion resistance, anti-loosening design, and installation specifications. A4-80 stainless steel bolts + flange anti-loosening nuts are the preferred solution for coastal/high corrosion environments. With torque control and insulation measures, the system life can be greatly extended. Investing in high-quality fasteners is more economical than later maintenance!
Post time: Aug-04-2025
