Zn-Al-Mg carbon steel PV brackets form potential difference with stainless fasteners and trigger galvanic corrosion. SUS304 only lasts 1 year in tidal flat coastal areas, far shorter than the 25-year design life of PV power stations.
| Material | Molybdenum Content | Salt Spray Hours Without Red Rust | Chloride Resistance Grade | Material Cost | Applicable PV Scenarios |
| SUS304 | 0% | 500h | Low chloride inland area | Base lowest price | Inland mountain & plain distributed PV |
| SUS316 | 2% | 1500h | Medium chloride riverside & mild coastal | +35% cost increase | Riverside lakeside, PV stations over 5km from coastline |
| 2205 Duplex Steel | 3% | 5000h | High chloride tidal flat & offshore floating PV | +120% cost increase | Tidal flat intertidal zone, offshore floating PV projects |
1. Inland mountain PV: Full SUS304 bolts & nuts with 0.8mm EPDM insulating gaskets to block galvanic corrosion of carbon steel brackets; 2. Riverside lakeside PV: SUS316 fasteners + 1.2mm thick hydrolysis-resistant EPDM gaskets, spray weather-resistant seal coating after installation; 3. Coastal tidal flat within 5km coastline: Full SUS316 fasteners + 1.5mm modified EPDM gaskets, anti-corrosion grease pre-coated on tracking bracket moving threads; 4. Offshore floating PV: Mandatory full 2205 duplex steel fastener set with fluororubber composite insulating gaskets to avoid long-term seawater pitting corrosion.
1. Misconception: Stainless steel never rusts — SUS304 without molybdenum pits severely under high chloride coastal environment; 2. Skip insulating gaskets between carbon steel brackets and stainless bolts: Massive white rust appears on brackets within 1 year; 3. Replace 2205 with SUS316 for offshore projects: Thread seizure occurs within 3-4 years, impossible to disassemble during maintenance.