What is an in-roof solar mounting system?

An in-roof (roof-integrated) system replaces the tiles or slates directly beneath the solar panels with a weathertight aluminium or plastic tray, so the panels sit flush with the roofline instead of standing above it on hooks and rails. The panels themselves form part of the roof covering, sealed to the surrounding tiles with flashings, waterproof strips and pre-compressed foam.

Is in-roof solar cheaper than on-roof?

On a new-build or full re-roof, in-roof is often cost-comparable because you save the tiles the panels would have covered. On a retrofit where existing tiles are still serviceable, on-roof is usually cheaper because you keep those tiles and only add hooks and rails. The trade-offs are aesthetic, planning and long-term roof condition rather than raw material cost.

What roof pitch does an in-roof system need?

Ranges differ by system. GSE Landscape Evolution is certified 15° to 50°. S4 RooFit has the widest window at 12° to 70° per its manufacturer datasheet. Viridian Clearline Fusion is certified 20° to 60° per its MCS BBA 0145 certificate. Below 12° water shedding is compromised across the board; between 12°–19° the choice narrows to GSE or S4; above 60° only S4 remains warranted, and even then safe installer access becomes the practical limit before the hardware does.

Which tile types are compatible?

All three systems in this guide work with interlocking concrete or clay tiles, natural and man-made slates, plain (flat) tiles and most curved pantiles. Deeply profiled tiles such as Roman or double Roman need a tilt filet under the bottom flashing to lift it to tile crown height. Metal, thatch and green roofs are not compatible.

Do I need MCS certification to install an in-roof array?

To claim SEG (Smart Export Guarantee) payments or connect a system covered by grants, the installation must be completed by an MCS-certified installer. The mounting hardware itself is MCS012 tested (GSE holds cert MCS IK0251); the installer's own MCS registration covers the electrical and structural work.

How is wind uplift calculated for in-roof arrays?

Wind load is calculated under BS EN 1991-1-4 using the site's wind zone (1–5 on the UK map), altitude, ridge height, roof pitch, terrain category, distance from the shoreline and the panel's position on the roof (centre, edge or corner). The mounting system's certified uplift capacity (2.25 kN/m² for GSE Landscape under MCS012) must exceed the calculated load in the worst-case zone the array occupies.

Can I mix panel brands in one in-roof array?

For S4 and GSE, yes — as long as every panel has the same width, height and frame thickness. The mounting frames are sized to millimetre tolerances, so a 1722×1134mm Aiko Neostar and a 1722×1134mm Trina Vertex-S can go in the same array. Viridian Clearline Fusion only accepts Viridian's own PV16 panels because the flashings are engineered around the exact PV16 profile.

Can I use Enphase micro-inverters or SolarEdge / Tigo optimisers with an in-roof array?

Yes, all three systems accept module-level power electronics. The key constraint is service access: once the panels are sealed in, any failed micro-inverter or optimiser requires the panel above it to be lifted. For Enphase, fix the micro-inverter to a batten through the GSE central frame hole, position it at the panel top edge, and leave a 200mm service loop in the Q-cable. For SolarEdge, factory-fitted S-series (SolarEdge-ready panels from Aiko, Trina and others) is the cleanest in-roof option because there is no external hardware to fail or retrofit. For Tigo, the TS4-A-F flex variants with MC4 tails are the easiest to retrofit later. S4's frame allows DC cable to be routed either beneath the tray or over it, giving more flexibility in siting the unit than a fixed channel. Designate one panel as the service panel and note it on the O&M drawings.

What is B-Roof (t4) and why does it matter?

B-Roof (t4) is the highest external fire performance classification under BS EN 13501-5, meaning the roof assembly resists penetration by burning brands and radiant heat. It is a common requirement for buildings within 6m of a boundary and for larger unprotected roof areas. The GSE In-Roof Landscape system holds B-Roof (t4) certification when installed to spec.

Do birds nest under in-roof panels?

Very rarely. In-roof arrays sit flush with the tiles so there is no gap for pigeons to nest under, which is one of their major advantages over on-roof systems. Pre-compressed foam seals the perimeter against birds, wasps and windblown debris. Bird deterrent mesh — which is essential for on-roof arrays — is not needed on in-roof.

How long does in-roof solar installation take?

For a two-person MCS crew, a typical 8–12 panel in-roof array takes 1 to 1.5 days on a retrofit (where existing tiles are being stripped) and slightly less on a new build (where the roof underlay and battens are already exposed). This is broadly comparable to on-roof installation once you account for tile stripping and reinstatement.

What warranty covers the installation?

The GSE In-Roof Landscape Evolution system is warranted for 10 years when installed per the manual using GSE-supplied EPDM-washer screws. S4 RooFit carries a 10-year warranty with a design life exceeding 25 years per the S4 manufacturer datasheet. Viridian Clearline Fusion carries panel and system warranties per Viridian's terms. On top of the manufacturer warranties, MCS-registered installers usually offer a 2- to 10-year workmanship warranty on the installation itself.

Can I get a trade discount?

Trade pricing is available on a case-by-case basis through the AIZO Partner/Affiliate Program — send us the project scope, panel count and delivery postcode and we'll quote against it. There isn't a fixed volume-tier structure; each project is priced on its own merits, which usually works out better than a rigid tier system on larger jobs.

Do you deliver mounting kits to site?

Yes. Larger orders ship on pallet to trade sites; individual components ship by carrier to residential addresses. Long items such as lateral flashings and bottom rails are palletised to prevent transit damage. UK mainland delivery is included for most orders; Highlands, Islands and Ireland attract a surcharge quoted at checkout or on the bespoke quote.

Guide d'achat des systèmes de montage solaire intégrés au toit

Coupe : les panneaux en surimposition dépassent du toit sur des crochets et des rails ; les panneaux intégrés remplacent les tuiles qu'ils recouvrent.

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Guide d'achat des systèmes de montage solaire intégrés au toit

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