Short answer: for utility-scale solar mounting, S750 zinc-aluminium-magnesium coated steel outlasts hot-dip galvanizing in the environments that kill solar farms — coastal salt, agricultural ammonia and industrial deposits — with 5,040-hour salt-spray resistance, a 30-year design life, 31.66% lower coating weight and roughly 30% less steel in the bracket. Hot-dip galvanizing remains right where a project specification explicitly demands it or for replacement parts matching an existing HDG fleet.
Head-to-Head Comparison
| Criterion | S750 Zn-Al-Mg | Hot-Dip Galvanizing |
|---|---|---|
| Salt-spray resistance | 5,040 hours (certified testing) | Typically several hundred to ~1,000 hours for comparable zinc mass |
| Cut-edge protection | Coating migrates and protects cut edges and punch holes | Cut edges and weld zones are bare and rust first |
| Process steps | Coil arrives coated — punch, form, ship | Fabricate, then hot-dip, then transport twice |
| Coating weight | 31.66% lower for equal or better life | Heavy zinc mass required for long life |
| Steel use per bracket | About 30% less (higher-strength base steel pairs with the coating) | Baseline |
| Design life | 30 years, rating edges of 20-year guarantees typical for HDG in harsh sites | Site-dependent; harsh sites consume coating early |
Why Cut-Edge Protection Decides Solar Projects
Brackets are punched, cut and drilled before they see a field. On hot-dip galvanized parts those edges are where rust starts and where 20-year guarantees are contested. The Zn-Al-Mg coating family was engineered to migrate over exposed steel at cut edges and punch holes, which is why the 5,040-hour salt-spray number survives real-world fabrication — not just laboratory panels.
Where Hot-Dip Galvanizing Is Still the Right Answer
Keep HDG when the owner’s specification names it explicitly, when replacement parts must visually and chemically match an existing HDG fleet, or when a structure is welded after coating in ways that make re-galvanizing practical. The honest comparison is per project — coating system, steel grade and fabrication route together decide the 30-year cost.
Is S750 coating available in the steel grades solar brackets need?
Yes — S750 Zn-Al-Mg coating is applied to structural grades suited to cold-formed brackets and channels, which is how the roughly 30% steel reduction is achieved without giving up section strength.
Does the 30-year design life come with documentation?
The coating performance is supported by certified salt-spray testing (5,040 hours) and published design-life guidance from the steel maker; project-specific documentation is included with quotations on request.