Choosing a Solar Mounting Structure for a Metal (Tin Shed) Roof
Trapezoidal metal sheets — often called tin-shed roofs — cover most factories, warehouses and sheds in India, and they are among the best surfaces for rooftop solar. The right mounting structure depends on three things: how the panels are oriented, how much clearance you need under them, and whether the structure should fix to the roof sheet or to the purlins below it.
Step 1: Portrait or landscape panels?
Portrait orientation (the long side of the panel running up the roof) usually fits more modules on a given roof area. Landscape orientation suits smaller or irregular roofs and low-profile layouts.
Mono Rail is designed for portrait layouts on trapezoidal roofs. Mini Rail and Long Rail are designed for landscape layouts.
Step 2: Crest-mounted or purlin-mounted?
Crest-mounted rails (Mono Rail, Mini Rail) sit on the raised crests of the roof sheet and are fixed with rivets and EPDM tape, or with structural adhesive where no penetration is wanted. They are fast to install and spread the load along the sheet.
Purlin-mounted rails (Long Rail) span across the roof and fix through to the purlins with self-drilling screws, often reusing the sheet's existing screw holes. They need fewer roof punctures and suit high wind-load zones, industrial buildings and asbestos cement roofs where the sheet itself should not carry the load.
Step 3: How much clearance?
Clearance between the panel and the roof lets air flow under the modules, which keeps them cooler and helps output in Indian summers. A lower profile reduces wind forces on the structure.
- 100 mm clearance — maximum ventilation; the common choice for commercial roofs (MonoRail 100 mm, MiniRail 100 mm).
- 70 mm clearance — lower profile for high wind-load or coastal sites (MonoRail 70 mm, MiniRail 70 mm).
- 65 mm clearance — the most compact Mono Rail option where height is limited.
Quick selector
| Your roof and layout | Suggested system |
|---|---|
| Trapezoidal sheet, portrait panels, commercial roof | Mono Rail (100 mm, or 70 mm for high wind) |
| Trapezoidal sheet, landscape panels, residential or small commercial | Mini Rail (100 mm or 70 mm) |
| Compact bays or short spans | Short Rail (part of the Mini Rail range) |
| Industrial shed or asbestos cement roof, high wind load | Long Rail (Light, Pro or Ultra) |
| Standing seam (clip-lock) roof | Standing Seam clamps — no drilling |
| Flat or low-pitch roof facing the wrong way | Inclined System (5°–20° tilt) |
Before you order
- Confirm the sheet profile (crest width and pitch) and the purlin spacing.
- Check the roof's age and condition — replace corroded sheets before installing.
- Get the site's design wind speed and ask for the structure's rating in writing.
- Plan a maintenance walkway so panels can be cleaned without stepping on them.