SolarPowerGuide
Solar panels on roof

Preparing Your Roof for Solar Panel Installation

A structurally sound, clean, and properly sealed roof is the foundation of a safe, efficient, and long-lasting solar PV system. Follow this step-by-step guide to prepare your roof before installers arrive.

Solar installation
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Step 1
Inspect Structure
Step 2
Clean Surface
Step 3
Seal & Flash
Step 4
Plan Layout

Introduction

Before installing solar panels, your roof must be structurally sound and properly prepared. This guide walks through roof inspection, repairs, and preparation to ensure safe and efficient installation — compliant with SANS 10160 and SAPVIA best practices.

Structural Assessment

Check roof strength, age, and material type. Reinforce weak areas as needed.

  • Roof Age: Less than 20 years preferred. Older roofs may need replacement.
  • Truss Spacing: Max 900 mm centers for IBR/corrugated.
  • Load Capacity: Minimum 15 kg/m² for panels + wind load (2400 Pa).
  • Engineer Sign-Off: Required for commercial or weak structures.

Pro Tip:

Get a structural engineer report — insurers often require it for solar warranties.

Cleaning and Surface Preparation

Remove debris, dirt, and moss. Ensure smooth, clean surface for mounting hardware.

What to Remove

  • Leaves, bird droppings, dust
  • Moss, lichen, algae
  • Loose paint or rust (metal roofs)
  • Old satellite dishes or vents

Tools & Methods

  • Pressure washer (low PSI)
  • Soft brush + mild detergent
  • Roof-safe cleaning solutions
  • Safety harness + non-slip boots

Waterproofing and Flashing

Install or inspect flashing to prevent leaks around mounts.

  • IBR/Corrugated: Use EPDM rubber seals + stainless bolts.
  • Tile Roofs: Replace tiles with flashings or use tile hooks.
  • Sealant: Use silicone-free polyurethane (e.g., Sikaflex).
  • Test: Hose test after flashing to confirm no leaks.

Warning:

Never drill into roof without proper flashing — 90% of leaks come from poor sealing.

Roof Layout Planning

Mark panel positions to optimize sunlight exposure and airflow.

Key Layout Rules

  • North-facing (Southern Hemisphere)
  • 30° tilt (optimal in SA)
  • Min 300 mm from roof edge
  • 100 mm gap between panel rows

Tools

  • Chalk line + tape measure
  • Laser level
  • PV*SOL or Aurora layout software
  • Shading analysis (sun path)

Conclusion

Proper roof preparation maximizes safety, efficiency, and longevity of your solar PV system. A well-prepped roof ensures 25+ years of leak-free performance and protects your warranty.

Next: Full Installation Guide