DEMO — fictional range. Local brief only, NOT SENT. No personal data is collected or transmitted.
FINISH
On a roof, the finish is the corrosion protection.
A balance-of-system part is expected to last as long as the modules. The finish is what makes that possible, and it is specified for the atmosphere rather than the appearance.
- Hot-dip galvanised
- Tray and structures · thick and durable, and it is dull
- Pre-galvanised strip
- Tray · a thinner coating, and cut edges are unprotected
- Powder coated
- Enclosures · coloured, and a scratch starts rust under the film
- Zinc plated
- Small parts · thin, and adequate indoors only
- Sheradised
- Fixings · uniform and thin, for parts that cannot be dipped
- Stainless, bare
- Coastal fixings · the alloy is the protection, and the grade decides how much
Illustrative finish reference
| Finish | Typical use | How it fails |
|---|---|---|
| Hot-dip galvanised | Roof tray and structures | Coating consumed over decades, then steel |
| Pre-galvanised | Indoor tray runs | Cut edges rust first |
| Powder coat | Enclosures | A scratch spreads under the film |
| Stainless A4 | Coastal fixings | Little, in the atmosphere it was chosen for |
Why cut edges are the weak point.
Because a pre-galvanised strip is coated before it is folded. Every cut and every drilled hole exposes steel, and those edges rust before the faces do. Touch-up is part of the specification rather than a finishing touch.
The one worth avoiding.
Powder coating a part that will be cut or drilled on site. The film is damaged at exactly the points that are then exposed, and the damage is hidden until the rust appears.