Onshore distributed and coastal offshore PV widely adopt carbon steel brackets matched with stainless steel fastening bolts. The electrode potential difference between two metals exceeds 0.25V, which easily triggers galvanic corrosion after moisture condensation, resulting in rapid thinning rust of carbon steel brackets and thread seizure of stainless steel bolts. It is a hidden hazard with the highest operation failure rate of PV projects. Simply thickening bolt coating cannot eradicate rust, and it is necessary to control dissimilar metal conductive paths. This article formulates standardized anti-corrosion schemes for PV sites based on GB/T15927.
| Insulating Gasket Material | Salt Spray Resistance Duration | Max Heat Resistance Temp | Outdoor Service Life | Applicable Scenario |
| Modified PA66 Nylon | 1800h | 95℃ | 5 Years | Inland Mountain PV |
| EPDM Rubber | 3200h | 110℃ | 8 Years | Riverside Humid PV |
| FRP Fiberglass | 5000h | 135℃ | 15 Years | Offshore Coastal PV |
1. Homologous material matching: Priority to adopt full 2507 duplex steel brackets and bolts for coastal high-salt projects to eliminate electrode potential difference; 2. Assembly insulation isolation: Install double-sided insulating gaskets on bolt head, shank and nut to cut off conductive circuit; 3. Sacrificial anode protection: Install zinc alloy sacrificial anodes on bracket sides to protect steel substrate via priority consumption.
1. Slight surface rust: Disassemble and clean oxide layer, replace with EPDM insulating gaskets, supplement conductive barrier anti-rust primer; 2. Bracket pitting corrosion: Install external zinc anodes and re-test bolt pre-tightening force to avoid stress-coupled corrosion; 3. Large-area rust: Eliminate thin-wall carbon steel brackets, replace with fiberglass anti-corrosion profiles and support full-insulation fastening kits.