PV Fastener Material Selection & Salt‑Spray Test Technical Guide for Solar Mounting Bolts

PV Fastener Material Selection & Salt‑Spray Test Technical Guide

Solar mounting fasteners work outdoors year‑round. Improper selection of material, coating or washer combination may cause rust, seizure or fracture, leading to loose brackets and potential safety risk for PV power plants.

1. Comparison of Common Materials

• 304 Stainless Steel: Cost‑effective for ordinary inland sites; not recommended for heavy salt‑spray coastal areas.
• 316 Stainless Steel: Better corrosion resistance than 304 for mild salt‑spray conditions with higher cost.
• 2205 Duplex Stainless Steel: High mechanical strength and excellent chloride‑resistance, widely used for coastal & island solar projects.
• Hot‑dip Galvanized Carbon Steel: Good cost performance for dry inland areas; anti‑corrosion layer needs regular inspection.

2. Salt‑Spray Test Reference

Inland projects usually require 48‑200h NSS neutral salt spray. Coastal salt‑spray sites recommend ≥500h salt‑spray hours. Duplex stainless steel delivers outstanding salt‑spray performance. Note: salt‑spray result is laboratory reference only and cannot fully simulate real outdoor conditions.

3. Washer Combination & Installation Tips

Follow standard sequence for flat washer and spring washer. Spring washers are not recommended for thin stainless‑steel sheets to avoid pitting corrosion. Control tightening torque; over‑torque causes thread galling and stress cracking. Anti‑seize compound is suggested for stainless steel fasteners to reduce thread seizure risk.

4. On‑site Inspection Reminder

Regularly check connecting parts for coastal PV stations, focus on thread zones and washer contact surfaces for corrosion signs.

Send us your site environmental conditions, we can provide customized fastener material suggestion for your project.