Most steel solar structures in India are either pre-galvanised (GI coil roll-formed into sections) or hot-dip galvanised (fabricated in black steel, then dipped in molten zinc). The choice affects life, cost and tender compliance.
Pre-galvanised
- Coil is zinc-coated before roll-forming
- Uniform, thinner coating
- Cut edges and punched holes are exposed (zinc offers some edge protection)
- Economical and lighter — common for rooftop systems
Hot-dip galvanised (HDG)
- Zinc applied after cutting, punching and welding
- Thicker coating that also covers edges and holes
- Preferred for ground-mounted, agricultural and corrosive sites
- Often specified in utility and government tenders
| Pre-galvanised | Hot-dip galvanised | |
|---|---|---|
| Coating applied | Before fabrication | After fabrication |
| Coating thickness | Thinner | Thicker |
| Edges & holes | Exposed | Coated |
| Cost | Lower | Higher |
| Typical use | Rooftop | Ground-mount, KUSUM, harsh sites |
Which should you choose?
Follow your tender or scheme specification first. Otherwise, choose HDG for ground-mounted, coastal, agricultural or industrial-pollution sites, and pre-galvanised for most urban rooftop systems where cost matters.