Solar Panels on Different Roof Types: Tile, Slate, Flat, and More

One of the first questions when considering solar panels is whether your roof is suitable — and a big part of that is the roof material and construction. While solar panels can be installed on a wide range of roof types, the complexity and cost vary significantly. This guide covers every common UK roof type and what installers look for when assessing suitability.

Concrete Interlocking Tiles — The Standard Case

Concrete interlocking tiles (the most common roof covering on UK homes built since the 1960s) are the simplest and most straightforward roof type for solar installation. Standard "S-hook" or "K2 mounting rail" systems attach to the existing roof battens beneath the tiles without any structural modification. A small number of tiles are lifted, hooks are screwed into the batten, and the tiles are replaced around the hook — creating a watertight, structurally sound anchor point for the mounting rail.

Concrete tiles are robust, relatively uniform, and easy to work with. Installation is typically fastest on this roof type, and the risk of cracking or damage is low. This is the installation type for which costs are most competitive.

Clay Tiles (Plain Clay, Pantiles)

Clay tiles are more common on older properties and require more care than concrete tiles. They are more brittle — particularly if they are original Victorian or Edwardian clay tiles — and the risk of cracking during installation is higher. An experienced installer will take extra precautions: using proper roof ladders and crawl boards to distribute weight, and carefully inspecting tiles before and after installation.

Plain clay tiles (flat, overlapping tiles typically found on older properties) and pantiles (S-shaped curved tiles common in parts of Yorkshire and East Anglia) both require specific mounting hooks designed for their profile. The cost of installation on clay tiles is typically £500–£1,000 more than on concrete tiles, reflecting the additional time and care required.

Natural Slate

Natural slate is the most challenging common roof material for solar installation. The issues are:

• Brittleness: Welsh, Spanish, and other natural slates vary enormously in quality and age-related brittleness. Old Welsh slate roofs in particular can be very difficult to work with without causing cracking and chipping.
• Replacement difficulty: When slates break during installation, replacements must closely match the original slate in size, thickness, and colour. Finding matching slates for old roofs can be difficult and expensive.
• Mounting method: Standard mounting hooks used on tile roofs cannot be used on slates. Instead, "S-brackets" or specific slate hooks must be used, which slide under adjacent slates for anchorage.

Despite these challenges, natural slate solar installation is routinely done successfully. The additional cost compared to concrete tiles is typically £800–£2,000 depending on slate age and condition. On Conservation Area or listed building properties, the planning authority may specify requirements for how mounting penetrations should be treated to maintain watertightness and appearance.

Artificial Slate

Artificial (fibre cement or composite) slates — common on homes built from the 1990s onwards — are significantly easier to work with than natural slate. They are more uniform, less brittle, and readily available for replacement if any are damaged during installation. Installation is comparable to concrete tiles in difficulty and cost.

Flat Roofs

Flat roofs require a different mounting approach: since panels cannot be laid flush to the roof (they need to be tilted towards the sun for optimal performance and self-cleaning), ballasted tilt frames are used. These are weighted metal frames that hold panels at 10–20 degrees of tilt, sitting on the flat roof surface without penetrating the roof membrane.

Key considerations for flat roof installations:

• Structural loading: Ballasted frames are heavy. A structural engineer's assessment may be needed for older flat roofs, particularly on extensions, garages, or flat-roofed bungalows.
• Row spacing: To prevent shading between rows of panels, rows must be spaced further apart than on a pitched roof. This means fewer panels per square metre of roof area.
• Membrane condition: The flat roof membrane (typically felt, GRP fibreglass, or EPDM rubber) should be in good condition before installation. A failing membrane should be repaired or replaced before solar panels are added.
• Drainage: Frames must not obstruct drainage channels or outlets.

Flat roof installations typically cost £500–£1,500 more than equivalent pitched roof installations due to the additional frames and engineering considerations.

Metal Roofing (Standing Seam)

Standing seam metal roofs — increasingly common on modern buildings and agricultural structures — are well-suited to solar installation using clamps that attach directly to the standing seam ribs without penetrating the roof surface. This is one of the cleanest and most watertight installation methods, with no drilling of the roof membrane required.

On corrugated metal roofing (common on agricultural buildings), specialist hooks that penetrate the corrugation at the structural rib are used. This is standard practice for agricultural commercial solar installations.

Green Roofs and Roof Terraces

Solar panels can be installed on green (sedum) roofs, though the structural loading and drainage requirements need careful assessment. The two technologies are increasingly being combined — the "bio-solar roof" concept — where solar panels shade part of the green roof, creating a different microclimate that benefits certain plant species while the panels benefit from the cooler temperatures created by the vegetation (solar panels are more efficient when cooler).

Roof Orientation and Pitch Optimisation

Beyond the roof material, the orientation and pitch affect system performance:

• Optimal orientation: True south (180 degrees) — but south-east through south-west produces near-optimal yields
• Optimal pitch: 30–35 degrees for maximum annual generation in the UK (slightly higher pitches improve winter generation slightly)
• East/West split: Installing panels on both east and west slopes is increasingly popular — while the peak generation is lower than a pure south installation, it spreads generation more evenly through the day, reducing the midday peak and export
• Shading: Any shading from chimneys, roof dormers, trees, or neighbouring buildings significantly reduces generation, particularly if string inverters are used without optimisers

What Happens During a Survey

A professional solar survey covers all of the above. Our surveyors assess:

• Roof material and condition
• Structural integrity (rafter spacing, batten condition)
• Orientation, pitch, and shading analysis (using satellite imagery and on-site measurement)
• DNO connection requirements
• Optimal panel layout for maximum generation within available roof area
• Planning status (Conservation Area, listed building)

The survey is free and forms the basis for a detailed, fixed-price quotation. Contact us to book a survey for your specific roof type.