How do Photovoltaic Bolts achieve the perfect combination of high strength and corrosion resistance?

In photovoltaic (PV) system construction, fasteners may be small in size but play a vital role. Especially photovoltaic bolts , as key components connecting solar mounting systems and panels, must possess both high strength and excellent corrosion resistance to ensure long-term system stability.

1. High Strength: The Core for Structural Safety
PV systems are typically installed outdoors — on rooftops, ground-mounted stations, or even in desert areas — where they face various environmental loads such as wind pressure, snow load, and seismic activity. Therefore, PV bolts must have sufficient tensile and shear strength.

Most high-quality PV bolts are made from high-strength carbon steel or alloy steel , treated with advanced heat treatment processes like quenching and tempering to achieve grade 8.8 or 10.9 strength levels . These bolts can withstand significant clamping force and resist loosening caused by vibration or load changes, ensuring overall structural stability.

Additionally, some premium bolts use cold forging + thread rolling technology , maintaining material grain structure integrity while enhancing surface hardness and mechanical performance.

2. Corrosion Resistance: Key to Withstanding Harsh Environments
Since PV systems are designed to last over 25 years, bolts will be exposed to humid, salty, UV-intensive environments for extended periods, making them prone to oxidation and rust, which can compromise structural safety and even lead to system failure.

To improve corrosion resistance, modern PV bolts commonly adopt the following protective methods:

Hot-dip galvanizing : Forms a dense zinc layer that provides both physical isolation and electrochemical protection, suitable for most outdoor applications.
Dacromet coating : An environmentally-friendly anti-corrosion coating with excellent durability, especially suitable for coastal or industrial areas.
Stainless steel materials (e.g., A2-70, A4-80) : Though more expensive, they perform exceptionally well in extreme corrosion conditions, widely used in marine or heavy-industry environments.

Composite coating technologies : Such as zinc-aluminum-magnesium coatings with organic sealers, gradually becoming a new trend to replace traditional galvanization with longer life and better environmental performance.
3. Combining Both: The Result of Scientific Material Selection and Process Optimization
Achieving the perfect combination of high strength and corrosion resistance is not simply about stacking materials, but rather the result of scientific material selection, rational design, and advanced manufacturing techniques .

Firstly, material choice should be based on local climate conditions and corrosion levels. For example, stainless steel or Dacromet-coated bolts are preferred in coastal areas, while hot-dip galvanized bolts are more cost-effective in inland regions.

Secondly, factors such as thread precision, fit clearance, and torque control significantly affect bolt performance. Using precision rolled threads and torque-tension controlled assembly techniques helps improve connection reliability.

Finally, by introducing automated production lines and rigorous quality inspection systems, each bolt meets standard requirements, ensuring high-performance products from the source.