India’s solar build-out has created a large and steady market for solar module mounting structures. Utility-scale parks, rooftop systems, carports and agricultural solar installations all need purlins, rafters, columns, bracings and clamps, and most of them are made from galvanised steel.
For fabricators and coil processors, that demand starts at the slitting line. Roll formers that produce C, U, Z and hat-section profiles need slit coils of precise width, while some components are made from flat sheets cut to length. This guide explains how GI coil slitting for solar structures works, which quality points matter most, and how to plan equipment for this market.
Materials Used in Solar Mounting Structures
- Pre-galvanised (GI) steel coils: Zinc-coated before forming, widely used for rooftop and lighter structures.
- Zinc-aluminium-magnesium (ZAM / ZM) coated coils: Increasingly specified for their corrosion resistance, especially at cut edges.
- Hot rolled steel for hot-dip galvanising: Formed first, then galvanised after fabrication, common for heavier ground-mount structures.
- Aluminium: Used for some rails and clamps, particularly in rooftop systems.
Each material has its own processing needs, but the common requirement is accurate width and good edge quality for roll forming.
How Slit Coils Become Solar Structure Profiles
- Master coil of GI, ZAM or HR steel is received from the mill.
- Slitting cuts it into narrow coils, each matched to the strip width (developed width) of a particular profile.
- Roll forming bends the strip into C, Z, U or hat sections.
- Punching and cutting add holes and cut members to length, often inline.
- Packing and dispatch to site.
Some flat components such as base plates, gussets and brackets are cut from sheets produced on a cut to length line.
Quality Points That Matter for Solar Structure Slitting
Width accuracy
Strip width decides the final profile dimensions. If the width varies, flanges will be uneven, which affects how purlins and rafters fit together on site.
Low burr and clean edges
Burr can mark roll forming tools, create sharp edges for installers and leave weak points where coatings fail. Good knife setting and sharp tooling are essential. Our article on camber and burr defects covers the main causes.
Camber control
Straight strip feeds smoothly into a roll former. Camber causes twist and bow in long profiles, which is a real problem for rafters and purlins several metres long.
Coating protection
Scratches and scuffs through the zinc or ZAM coating create starting points for corrosion. Smooth rolls, correct pass line and careful recoiling help protect the surface.
Well-wound coils
Tight, even coils without telescoping load easily onto roll former decoilers and travel safely.
Choosing a Slitting Line for Solar Structure Material
Thickness range
Solar structure profiles typically use light to medium gauges. Check the full thickness range you plan to run, including heavier columns for ground-mount structures. A light gauge slitting line suits thinner coated material, while thicker HR material for post-galvanised structures may need a heavy gauge slitting line.
Number of cuts and width combinations
Fabricators often run several profiles from one master coil. A line that handles your common width combinations efficiently reduces edge trim scrap.
Fast changeovers
Solar projects come with tight delivery schedules and frequent width changes. Quick knife changes keep the line productive.
Scrap handling
An edge trim winder or chopper keeps the line running cleanly. Plan your width combinations to minimise trim; our guide to reducing material waste in coil slitting has practical tips.
Coil packing
Coated coils stored at project sites or in yards need protection from moisture. A coil wrapping machine helps prevent white rust and edge damage.
Example: Planning Widths from a Master Coil
Suppose a fabricator runs three profiles with developed widths of 250 mm, 300 mm and 180 mm, and buys master coils 1,250 mm wide. A combination of two 300 mm, two 250 mm and one 180 mm strips uses 1,280 mm, which is too wide. Switching to two 300 mm, one 250 mm and two 180 mm strips uses 1,210 mm, leaving 40 mm of total edge trim. Planning combinations like this for each order improves yield noticeably over a year.
The exact figures will depend on your profiles and coil sizes, but the principle is the same: plan widths before you slit.
Opportunities for Processors
- Dedicated supply to structure fabricators who do not want to invest in their own slitting line
- In-house slitting for large fabricators to control lead times and material cost
- Combined slitting and CTL capability to supply both profiles and flat components
Valgo Machinery builds slitting lines, cut to length lines and coil packing systems for processors serving the solar and construction sectors. Contact us to discuss a line for your material range.
Frequently Asked Questions
What steel is used for solar mounting structures?
Common choices are pre-galvanised GI steel, zinc-aluminium-magnesium coated steel, and hot rolled steel that is hot-dip galvanised after fabrication. Aluminium is also used for some rails and clamps.
Why is slitting needed for solar structures?
Roll formers need strip of an exact width to produce each profile. Slitting cuts wide master coils into those narrower widths.
How does burr affect galvanised solar profiles?
Burr can damage roll forming tools, create sharp edges and expose areas where the coating can fail, increasing the risk of corrosion.
Can one slitting line handle GI and ZAM coils?
Yes, if the line’s thickness range, tooling and surface protection suit both materials. Discuss the grades with your machine supplier.
Do solar structure makers also need a cut to length line?
Often yes. Base plates, gussets and brackets are usually made from flat sheets produced on a cut to length line.