Solar Structure
Table 1: General structural material specifications for rooftop solar mounting
| Component | Material / Standard | Specification Details |
|---|---|---|
| Structural Steel | IS 2062:2011 | Used for MS structures |
| Galvanization | IS 4759 / EN 1461 | Hot-dip galvanization of mounting structures |
| Aluminium | AA6063 T6 | Used especially for light structures or corrosion-prone areas |
| Fasteners | SS 304 / HDG Grade 8.8 | Corrosion-resistant; SS-304 for module clamping |
| Welding Tests | IS 822, ER 70 S-6 wire | DP Test (crack/pinhole), certified weld wire |
| Zinc Quality | IS 209 | 99.999% purity recommended for hot dip galvanizing (Hindustan Zinc Ltd or equivalent) |
| Anchor Bolts (Foundation) | IS 5624 | Minimum Ø12 mm, length ≥100 mm if roof penetration is allowed |
| Foundation Concrete Grade | IS 456 | Minimum M20 |
| Load Design | IS 6403, IS 875 (Wind Load), IS 4091 | Structure must meet wind speed and structural integrity for 25 years |
Table 2: Mounting structure dimensions and Type-wise specification
A. Ballast type (Non-penetrating RCC roofs)
| Specification Item | Details |
|---|---|
| Type | Ballast (Non-invasive) |
| Clearance from Roof | 70–150 mm |
| Weight for Ballast | M25 grade concrete blocks |
M25 concrete is a specific grade of concrete that achieves a compressive strength of 25 megapascals (MPa) after 28 days of curing. It is made of: - Cement: 1 part - Water: 1 part - Sand (fine aggregate): 2 part - Aggregates (coarse aggregate): 4 parts
C. Tin shed mounting
| Specification Item | Details |
|---|---|
| Tilt Type | Aligned with slope or optimized based on south-facing tilt |
| Clearance | Minimum 100 mm from tin shed |
| Structural Thickness | All members ≥ 2 mm |
| Mounting | Riveted on purlins of tin shed |
C. RCC elevated structures
| Clearance Height | Base Plate Thickness | Column Section | Rafter Section | Purlin Section | Bracing Thickness | Remarks |
|---|---|---|---|---|---|---|
| 300–1000 mm | 5 mm | Lip 2 mm / C-Channel 3 mm | Lip 2 mm / C-Channel 3 mm | Lip 2 mm | 2 mm | Min ground clearance: 500 mm |
| Web: 70 mm, Flange: 40 mm | Web: 70 mm, Flange: 40 mm | Web: 60 mm, Flange: 40 mm | ||||
| 1000–2000 mm | 6 mm | Lip 2 mm / C-Channel 3 mm | Lip 2 mm / C-Channel 3 mm | Lip 2 mm | 2 mm | |
| Web: 80 mm, Flange: 50 mm | Web: 70 mm, Flange: 40 mm | Web: 70 mm, Flange: 40 mm | ||||
| 2000–3000 mm | 8 mm | Square/RHS: min 2.6 mm | Lip 2 mm / C-Channel 3 mm | Lip 2 mm | 3 mm | SHS: min 50×50 mm; RHS: min 60×40 mm |
| or C-Channel 3 mm | Web: 80 mm, Flange: 50 mm | Web: 80 mm, Flange: 50 mm | ||||
| >3000 mm (Super Elevated) | 10 mm (Base), 5 mm (Upper) | Base: SHS min 2.9 mm (60×60) or RHS 80×40 | Same as above for upper structure | Same as above | 2 mm (upper), 4 mm (base) | Sag bar (12 mm dia) if X-distance > 3 m |
Table 3: Standards for structural safety and material testing
| Purpose | Indian / International Standard |
|---|---|
| Structural steel | IS 2062 |
| Sheet steel | IS 1079 |
| Pipe/round/square sections | IS 1161, IS 1239, IS 4923 |
| Welding standards | IS 822 (Dye Penetration Testing) |
| Zinc galvanizing | IS 4759, IS 2629, IS 6745, IS 2633, EN 1461 |
| Foundation design | IS 456, IS 6403, IS 4091, IS 875 |
| Anchor/Fastener quality | IS 5624 |
Table 4: Stucture type suitability
| Property | Strut Channel | C-Channel | Lip Channel | Square Hollow Section (SHS) | Rectangular Hollow Section (RHS) |
|---|---|---|---|---|---|
| Shape | U-shaped with inward lips | Open C-shape | C-shape with return lips | Fully closed square tube | Fully closed rectangular tube |
| Cross-section View | 🭖 | 🡇 | 🡣 | ◼ | ▭ |
| Tensile Strength Range | ~250–350 MPa (mild steel or slotted GI) | ~350–450 MPa (IS 2062 standard) | ~350–450 MPa (IS 2062 / cold-formed steel) | ~350–500 MPa (IS 4923 structural steel) | ~350–500 MPa (IS 4923 structural steel) |
| Strength Profile | Moderate (adjustable but limited load) | Moderate to high (good axial, weak torsion) | Higher than C-channel (better stiffness) | Very high (excellent axial and torsional) | Very high (excellent directional strength) |
| Ease of Fabrication | Very high (slots pre-drilled) | Moderate (requires welding/cutting) | Moderate (extra bends needed) | Low (welding and cutting needed) | Low (welding and cutting needed) |
| Use as Channel | ✔️ Light-duty only | ✔️ Standard | ✔️ Good strength-to-weight | ❌ Not preferred | ❌ Not preferred |
| Use as Rafter | ❌ Not recommended | ✔️ Common | ✔️ Better for long spans | ✔️ Strong and reliable | ✔️ Strong and preferred for long spans |
| Use as Purlin | ❌ Not recommended | ✔️ Used in low-load areas | ✔️ Preferred for mid-spans | ❌ Rare (costlier, heavy) | ❌ Rare (costlier, heavy) |
| Common Application | Instrument trays, lightweight structures | Low- to mid-rise solar MMS | Mid-rise solar MMS (RCC, tin) | High-elevation or heavy-load MMS | High-elevation, long-span or cantilever MMS |
| Torsional Resistance | Poor | Poor | Moderate | Excellent | Excellent |
| Cost | Low | Low to moderate | Moderate | Moderate to high | High |
| Best Feature | Modular and easy to assemble | Easy availability and simple design | Balance of cost and stiffness | Superior strength and uniform load handling | Directional stiffness and load optimization |
| Limitations | Not load-bearing, not for primary support | Needs bracing in large spans | Heavier than strut, more fabrication needed | More expensive, harder to fabricate onsite | Heavier, expensive, not ideal for small systems |