Pitched Roof Solar Mounting for Tile & Slate Roofs: The Complete UK Buying Guide

Why pitched-roof mounting is different

Pitched-roof solar is a very different job from a flat roof array. On a flat roof you can lean on ballast weight, choose your ideal tilt, and never touch the membrane. On a tile or slate roof the panels sit at whatever pitch the roof already has, the load has to transfer through the tiles and down onto the rafters, and every fixing point has to remain weatherproof for the life of the array — thirty years and beyond.

That changes what you're buying. The mount is a rail-and-hook system, not a tray. The hook slides under a tile to bolt onto the rafter, the rail bolts to the hook, the module clamps to the rail, and — critically — a flashing sits between the hook arm and the tile above to shed water past the intrusion. Get any one of those wrong and you either lose watertightness, or you fail wind-load calculations, or you crack tiles the first time someone walks the roof to service the panels.

Two brands cover this job well in the UK: Fastensol for a lower-cost hook-per-tile-type approach with 12-year warranty and MCS certification (MCS IK0251), and Renusol for a heavier-duty VarioSole+ platform with hooks rated for high snow and wind zones. Both take a standard framed module and both interface with tile flashings from Genius Roof Solutions, Deks, and others.

Pick the right hook for your tile type

The hook is the part that has to work with your specific tile shape. Profiled tiles (pantiles, Romans, Spanish, coppo, concrete profile) all have a curve that lets a shaped hook sit under the tile without lifting the courses either side. Flat tiles (plain, concrete flat, slate) don't — the hook has to be low-profile, and you may have to notch or shave a tile to clear the arm.

Hook compatibility matrix

The matrix below maps each UK roof profile to the Fastensol and Renusol hooks that suit it. The Fastensol installation manual identifies seven hook variants across the TH01–TH15 range covering every common tile shape; Renusol split the same job between three UK-specific hooks (Pantile, Plain Tile/Slate, and High Load).

Anatomy of a pitched-roof mount

Every pitched-roof PV mount is built from the same six part families, whichever brand you're using. Understanding what each one does makes it much easier to specify or diagnose a bill of materials.

1. Rafter fixing. The load path is always into structural timber — never into the batten alone, and never into the tile. Fastensol supplies M6.3×80 wood screws with each hook; Renusol sells them separately as pan-head 6×80 (R-900305-21 single, R-900333 pack of 100), or slate-specific countersunk (R900013).
2. Roof hook. Chosen from the matrix above. Every hook has a foot that beds on the rafter/batten and an arm that lifts clear of the tile above it.
3. Flashing. Sits under the tile that overlaps the hook, and channels water past the hook arm. Genius Roof SolarFlash and Deks SolarDek TileFlash are the two big families here — covered in the Flashings section below.
4. Rail. Bolts to the hook, running perpendicular to the rafters. Fastensol supplies 3550mm rails in silver (F-R3550-GS) and black (F-R3550-BL); Renusol supplies VarioSole+ rail in 41×35 and 50×37 profiles up to 4.8 m long, both black and silver.
5. Clamps. Mid clamps hold the panel between two adjacent modules; end clamps hold the last panel at the end of a row. Fastensol Universal Clamp (F-UC-B) covers 30–40 mm frames; Renusol End Clamp+ (R-420081) covers 30–50 mm. Both interface with Fastensol Rail Bolt M8 T-nuts (F-TN-GS) or Renusol Bracket IFP (REN-420024).
6. Rail splices and end caps. Runs longer than a single rail need a splice — Fastensol Rail Splice (F-RS200-GS) joins two Fastensol rails end-to-end. Rail ends get a rubber cap: Fastensol F-MR-B (black/silver), Renusol REN-900276 (black) or R-920044 (grey pair).

The Fastensol pitched range

Fastensol is MCS-certified (MCS IK0251) and carries a 12-year product warranty with a 5-year finish warranty on the anodised aluminium. It's the value-focused choice for straightforward residential installs — a hook per tile type, one rail profile, one universal clamp, and it's done. Structural certification is by Don Moore & Associates for wind zones up to and including UK Terrain Category 2 conditions.

Fastensol roof hooks

Fastensol rails, splices & clamps

The Renusol pitched range

Renusol is the heavier-duty option: German engineering, VarioSole+ platform, and hooks with a HIGH LOAD variant (R-420184) rated for extreme wind and snow zones. It costs more than Fastensol per component but is the standard specification for commercial roofs, exposed sites, and any installation where the client wants a name-brand aluminium platform with documented load calcs.

Renusol roof hooks

Renusol VarioSole+ rails & connectors

Renusol clamps & fixings

Flashings & waterproofing

Every hook that lifts a tile arm above the roof line creates a potential path for water. A flashing is the purpose-made lead, EPDM, aluminium or lead-free bib that sits under the tile above the hook and channels rainwater past the intrusion, so the roof stays watertight for the life of the array. This is the single most-overlooked line on solar bills of materials — and the single most expensive omission when it fails.

Genius Roof SolarFlash kits

Genius Roof Solutions manufactures purpose-designed flashing kits for each UK roof type, and one specifically designed to pair with the Renusol RH flat-bracket plain-tile hook. All are in stock.

Genius Roof Zero Lead flashing rolls

For continuous flashing runs — around chimneys, or across arrays where individual kits become uneconomic — Zero Lead is a self-adhesive lead-free flashing roll that's lighter and safer to handle than traditional lead. Two widths in stock.

Deks SolarDek & Dektite cable flashings

Deks Industries makes flashings for both the hooks themselves and for the DC cable penetrations from panels into the roof void. Every array needs cable flashings — this is where the string wiring enters the loft to reach the inverter, and it's the second most common failure point after the hooks themselves.

Slate roof specialities

Slate is the trickiest UK roof material for solar — brittle, laid in overlapping courses that resist any lifting, and fixed with nails that are essentially inaccessible once the slate above is dressed. Two brands solve two different bits of the problem.

Fastensol vs Renusol: side-by-side

Both brands do the same job well. Which one you specify comes down to project scale, wind zone, and budget. This table compares the two on the metrics that actually affect a purchasing decision.

In practice, most UK residential arrays under 12 kWp on standard-exposure sites are speced with Fastensol for cost reasons. Renusol wins on commercial roofs, arrays above ~15 kWp, exposed coastal sites (South West, Highlands, Northern Isles, East Anglian coast), and any job where the client is going to see the load calcs.

Bird deterrent add-ons

Pigeons and gulls nest under solar panels — the panel provides shelter, warmth from the module underside, and a predator-safe cavity. Once nesting starts, the array sees a measurable performance drop from droppings on the frame edges, cable damage from beaks, and — in extreme cases — string failures. Prevention is cheap; retrofit removal after infestation is expensive and unpleasant. Fit deterrents at commissioning.

Three product families cover the job, all in stock at the bird deterrent collection: continuous mesh (blocks the entire perimeter gap), spike strips (makes landing uncomfortable), and needle rolls (a hybrid that combines a spine with upward needles).

EnviroGuard — mesh & spike systems

BirdBlocker — reinforced needle rolls

Probird — flexible spike strips

Interactive kit builder

Pick your roof type, panel count, brand preference and options — the tool generates a live bill of materials with quantities, per-line costs, and a running total inclusive and exclusive of VAT. Every part links directly to its product page for one-click ordering. Numbers are indicative; a full survey may vary the hook count based on rafter centres and wind zone.

Installation & wind-load notes

The full technical detail for a compliant install is in the manufacturer manuals — Fastensol's GS Roof Tile Roof Installation Guide (PUB22 JAN22) and Renusol's VarioSole+ Planning Guide. Both are available on request or from the brand websites. The high-level rules that always apply:

Rafter fixing depth & direction

Every hook goes into the structural rafter — never into the batten or the underlay alone. Minimum embedment depth is 60 mm into softwood, 40 mm into hardwood. Use the correct wood screw grade (6×80 pan-head or countersunk from Renusol; supplied with Fastensol hooks). A minimum of two screws per hook, three for High Load or extreme wind zones.

Hook spacing & rafter centres

Hook spacing is set by the lesser of: (a) the module clamping range specified by the panel manufacturer (typically the quarter-points of the frame), and (b) the maximum span from the mounting brand's structural table. For Fastensol on a UK Terrain Category 2 site, that's 1.2 m maximum between hooks; for exposed / coastal it drops to 1.0 m, and for highland or cliffside to 0.8 m. Hooks are counted per rail run: for each rail, take the rail length (columns × panel width), divide by the maximum spacing, round up, then add 1. Multiply by 2 rails per row of panels, then by the number of rows. A common 12-panel array in a 2×6 portrait layout at standard exposure needs 28 hooks — not 48. Consult the Fastensol IK0251 manual for the full wind-zone table.

Wind zone & snow load

The UK site altitude, terrain category and roof pitch drive both wind pressure (per BS EN 1991-1-4) and snow load (per BS EN 1991-1-3). The Fastensol manual includes the UK basic wind velocity map and snow zone map; use these to determine whether you can use a standard hook or need the Renusol HIGH LOAD variant. Coastal, Highland and exposed elevated sites almost always benefit from HIGH LOAD or triple-fixing per hook.

Grounding & bonding

Every framed module needs to be electrically bonded to the mounting rail. Fastensol supplies grounding lugs and bonding jumpers; the Renusol platform uses toothed washers under the clamps to bite through the anodising. Both brands satisfy BS 7671 requirements when installed to their manuals. The DC-side grounding wire runs from the array to the inverter's earth terminal — cable size and route per the electrician's design.

Frequently asked questions