Industry News
How to choose solar PV racking fasteners? Material, coating and anti-loosening essentials
2026-09-06
Compiled by JIALI Industrial (164.hk) — a Hong Kong fastener supplier specialising in screws, bolts, nuts and selection know-how.
Service environment and selection pain points
Utility-scale and rooftop solar plants are typically designed for a 25-year service life, yet racking systems sit outdoors year-round: thermal cycling, wind vibration and coastal salt spray loosen and corrode ordinary plated fasteners within a few years. A shifted module angle directly cuts power output, and replacing corroded racking bolts later means downtime and high labour cost. The first rule of solar fastener selection is to base material and coating on the site corrosion category and wind-load condition — not to copy indoor hardware.
Material and coating choices
In dry inland regions, hot-dip galvanised carbon steel meets the job, with coating thickness controlled to GB/T 13912 (typically 55–85 μm) for 20+ year protection. For coastal or high-humidity sites, specify 304 / 316 stainless steel (ISO 3506 A2 / A4) for racking joints — 316 handles chloride environments best. Watch galvanic corrosion: when aluminium racking profiles contact galvanised steel in wet conditions, the aluminium corrodes faster; switch to stainless hardware or add an insulating washer. For demanding cases, Dacromet offers a uniform, salt-spray-resistant coating.
Critical joints and anti-loosening design
Main-beam to post connections typically use 8.8 grade galvanised or 304 / 316 stainless bolts (GB/T 5782, ISO 4014) with large flat washers to spread wind-load stress. Module clamps and frames are usually fixed with stainless bolts plus nylon-insert lock nuts. Tracking systems and pivot joints see continuous movement, so vibration loosening is the top risk — use nylon-insert lock nuts (DIN 985 / GB/T 889) or flange lock nuts (DIN 6923 / GB/T 6177) there. Before batch supply, ask for material certificates and an ASTM B117 salt-spray report, and check coating thickness. Need solar racking fastener selection support? Contact JIALI Industrial (164.hk) with your site environment and drawings for a fast match.
Related Reading
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- Fastener terminology EN–ZH glossary: essential screw & bolt vocabulary for procurement
- JIALI launches Stainless Steel zone with full 304 / 316 range
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