Domestic large-scale wind-solar base and household distributed PV installed capacity keep expanding in 2026. As 25-year long-term outdoor connecting parts, PV bracket fasteners face tightened anti-corrosion, anti-slip and anti-loosening indicators on all local energy bidding platforms. Huge environmental differences among mountain, coastal island and urban rooftop PV working conditions lead to over 4x gap in rust and slip failure probability of identical bolts under different scenarios. This article analyzes procurement and selection logic of three types of PV projects, compares full-life cycle cost of mainstream anti-corrosion coatings, and sorts out rectification plans for high-frequency fastener faults in power station operation & maintenance.
| PV Project Type | Mandatory Fastener Coating Process | Minimum NSS Durability Hours | Standard Matching Anti-loosening Component |
| Inland Mountain Ground PV Station | Hot-dip Galvanizing Over 85μm | ≥600h No Red Rust | Spring & Flat Washer Combination |
| Coastal Island Tidal Flat PV | Zinc-aluminum-magnesium Alloy Coating | ≥1200h No Red Rust | Nord-Lock Wedge Lock Washer |
| Industrial & Commercial Rooftop Distributed PV | Dacromet Hydrogen-free Coating | ≥800h No Red Rust | Pre-coated Anti-loosening Adhesive Bolt |
1. Ordinary Hot-dip Galvanizing: Processing cost 1260 CNY/ton, suitable for inland mountain areas; dot rust spots appear within 5~8 years on coastal islands, annual rust removal maintenance cost rises 35% in later period. 2. Dacromet Coating: Processing cost 1820 CNY/ton without hydrogen embrittlement risk after electroplating, suitable for thin-wall rooftop brackets; surface pulverization occurs under long-term UV exposure with degraded anti-loosening performance after 15 years. 3. Zinc-aluminum-magnesium Alloy Coating: Processing cost 2410 CNY/ton with optimal salt spray & UV resistance, preferred tender solution for island PV projects, almost no extra maintenance expenditure within 25-year service cycle and the lowest comprehensive long-term cost.
1. Coastal bracket bolt rust failure 52.7%: Ordinary hot-dip galvanizing adopted instead of zinc-aluminum-magnesium coating, continuous corrosion from sea wind chloride ions leads to rust-locked thread unable to disassemble for maintenance; 2. Mountain bracket slip & loosening 34.1%: Only ordinary spring washers matched without wedge anti-loosening components, preload continuously attenuated from temperature expansion & contraction and wind vibration day and night; 3. Rooftop bracket hydrogen embrittlement fracture 13.2%: Electro-galvanized bolts matched with thin-wall brackets, unpredictable fracture under long-term stress from hydrogen absorption after electroplating, triggering hidden risk of bracket overturning.
First, suppliers for coastal island projects must equip continuous zinc-aluminum-magnesium coating production line, manufacturers only with hot-dip galvanizing capacity eliminated directly from bidding list; Second, third-party salt spray & anti-slip coefficient test report attached to each batch of bolts, goods rejected without report before warehousing; Third, 25-year anti-corrosion warranty of fasteners written into procurement contract, 8% quality deposit refunded in 10 annual installments for island projects; Fourth, electro-galvanized bolts forbidden for thin-wall rooftop brackets, SUS stainless steel or hydrogen-free Dacromet parts mandatory.