What are Your Mounting Options When Installing Solar Panels?

Understanding the mounting options for solar panels is essential for quality installation and compliance with building regulations. Solar PV mounting systems vary depending on roof type, structural capacity and required performance.

Here is an overview of the common mounting systems encountered in everyday roofing projects.

A Roofer’s Guide to Solar Mounting Systems

In 2025, there were more than 203,000 certified solar installations in the UK, setting a record annual high. Growth is set to continue as the Future Homes Standard is likely to mandate solar panels for new builds. The panel mounting solutions generally fall into three categories:

• On-roof railed systems, fixed above the existing roof covering
• In-roof integrated systems, with flush panels replacing part of the roof covering
• Flat-roof solutions, including ballasted/weight-based and mechanically fixed frameworks

Each option has trade-offs in structural impact, weatherproofing challenges and labour involvement. Roofers must assess the roofing substrate, pitch, access, fire strategy and expected loads before settling on a mounting concept.

Preinstallation Essential Checks

Before any hardware is selected or holes are drilled, a set of mandatory preinstallation assessments should be completed.

• Structural survey: Professionals should confirm that the roof’s rafters, trusses and decking can bear the extra dead load of panels plus the mounting system and anticipated wind or snow forces. Local Authority Building Control may require structural evidence if loading increases by 15% or more and thereby constitutes a material alteration.
• Roof condition: Inspection for wear, rot and age of materials is vital. Installing on a roof nearing the end of its lifespan can necessitate early rework and compromise longevity.
• Compliance: Roofers should check whether the work falls under permitted development rights and assess applicable building control requirements. Certain roof work may require planning consent.
• Certification standards: Systems must meet relevant certifications, especially the Microgeneration Certification Scheme (MCS) 012 Solar Mounting Standard for pitched and flat roofs. This includes documentation covering fixings, weather performance and design limitations.

On-Roof Mounted Systems – A Technical Walk-Through

On-roof mounting remains the most common installation method, particularly for pitched roofs. The basic workflow comprises:

1. Layout and array planning: Professionals map out the PV array footprint, identify rafters — the first should be within 18 inches or 457.2 millimeters of the array edge — and establish rail alignment lines. Mountings should be aligned to secure into primary structural members, not just battens.
2. Attachment and weatherproofing: Roof-specific flashings and brackets maintain weathertightness. Penetration points must be sealed and compatible with the roofing material’s profile.
3. Rail and module fixing: Roofers level and secure rails, install grounding and bonding, then affix PV modules, ensuring manufacturer torque specs and spacing are respected.

While method steps vary with roof material, the core principles of minimising structural stress and preventing moisture ingress remain constant.

Solutions for Common Roof Types

The most common roofing situations require specific treatment.

1. Tiled Roofs — Concrete and Clay

Mounting on tiled roofs typically uses hooks that sit under the tiles and fasten to the rafters without cutting the tiles. Roofers should ensure the hook and flashing system suits the tile profile to maintain weatherproofing.

As the principal protection against storms and weather events, the roof’s integrity must always be the top priority. Avoid point loads that can cause tile cracks and use sealants as specified for maximum longevity.

2. Slate Roofs

Slate is brittle and unforgiving. Roofers should use specialised slate hooks that spread loads and avoid cracking. Flashing compatibility and careful tile lifting are critical. Improper installation easily causes leakage and slate breakage.

3. Metal Roofs

Metal roofs present two profiles:

• Standing seam: Roofers use nonpenetrating clamps that grip seams. This avoids holes and preserves waterproofing, but competence in handling seam profiles is essential.
• Trapezoidal/through-fix: Mechanically fixed brackets that match the rib profile are used. Proper sealing around fixings is critical to avoid water ingress.

4. Flat Roofs

Flat roofs present a different set of challenges due to their lower pitch and the resulting uplift forces.

• Ballasted systems: Weighted trays or blocks hold arrays in place without penetrating the membrane. Ballast distribution must be calculated for local wind loads.
• Mechanical fixed systems: Where penetrations are unavoidable, flashings and membrane reinstatement must be executed to maintain watertightness.

5. In-Roof Integrated Solar Systems

These replace part of the roof covering. They offer an aesthetic flush finish and can integrate neatly with certain slate or tile systems. Because integrated panels do not need a mounting system, the installation weighs less, making it suitable for homes that may not support a roof-mounted load.

However, because the panel and trays replace waterproof layers, roofers must pay close attention to the edge details, flashing and drainage paths. The integrated board and clips often require bespoke cutting and sealing work.

The Roofer’s Role in a Successful Solar Project

The choice of solar mounting system is a blend of structural understanding, regulatory compliance and material-specific technique. Whether installing on pitched or flat roofs, adhering to standards and carefully planning around the structure and weatherproofing will result in durable and compliant installations every time.