In-Roof Solar Integration

How in-roof PV is built into the roof during construction, and why it is the usual specification on FHS-compliant new builds.

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In-Roof Solar Integration — UK new build solar installation

About this service

In-roof (sometimes called "roof-integrated") solar replaces the tiles or slates it covers rather than sitting on top of them. On new builds it is the usual specification under Part L 2026 because it is fitted during the roofing stage, avoids a second scaffold and roof visit later, and sits flush with the finished roof. Common in-roof mounting systems include GSE Integration, Marley SolarTile, Easy-Roof, K2 In-Roof and Viridian Solar Clearline Fusion.

Who it's for

Volume housebuilders
SME developers
Self-builders
Custom-build plot owners

How it fits into a new-build programme

In-Roof Solar Integration is specified at design stage, entered into the SAP 10.3 calculation, installed during construction and documented at handover. When you compare quotes, check the installer's MCS certification for this technology, the length of the workmanship warranty and who backs it, and what the handover pack will include.

40% of ground floor area

PV / ground floor area

Mar 2027

FHS in force

75%

CO₂ vs 2013 baseline

£4,350 per dwelling

Per-plot premium (2025 prices, FHS Impact Assessment)

For developers and housebuilders

In-roof solar integration on volume new-build programmes

On a multi-plot programme, settle four things at procurement: the per-plot price and how it moves with inflation; whether the array is modelled in the SAP 10.3 calculation for every house type; what your structural warranty provider needs to see for roof-integrated PV; and who issues the MCS certificate at handover, since buyers need it to claim Smart Export Guarantee payments.

Developer guide →

For self-builders and architects

In-roof solar integration for one-off custom builds

On a one-off build the array is easiest to settle at RIBA Stage 2 or 3, while the roof geometry is still open. Your SAP assessor models the system for the Part L submission, your building control body signs it off, and PV installed as part of constructing a new dwelling is zero-rated for VAT under HMRC Notice 708.

Self-build guide →

How this fits into the FHS compliance pathway

Every FHS-compliant new build passes three regulatory gates. In-roof solar integration sits mainly in the second, design-stage Part L compliance, but it affects building control sign-off and the handover documents too:

1
Planning permission Solar PV designed into a new dwelling is normally covered by the dwelling's own planning permission. Conservation areas, Article 4 directions and plots within the curtilage of a listed building need extra planning evidence, usually prepared by the architect or planning agent.
2
Building control: Part L compliance SAP 10.3 is the compliance calculation at FHS launch. The dwelling's emission and primary energy rates must meet their targets, with the PV array, heat pump, fabric U-values and air permeability all entered. The SAP assessor prepares the design-stage and as-built calculations that building control reviews.
3
Completion: certificates and handover The MCS certificate (needed for Smart Export Guarantee payments), the Energy Performance Certificate and the homeowner's handover documents. If your structural warranty provider has requirements for roof-integrated PV, confirm them before the roof goes on.

For a fuller walkthrough of the compliance process, see the Part L 2026 guide and the FHS PV calculator, which sizes a compliant array from your ground floor area.

Frequently asked questions

What is the difference between in-roof and on-roof solar?

In-roof systems sit flush with the roofline, replacing tiles in the array area. On-roof systems mount above the finished roof covering. On new builds, in-roof is the usual choice because it is fitted during the roofing stage rather than as a separate visit afterwards.

Which in-roof mounting systems are common?

GSE Integration, Marley SolarTile, Easy-Roof, K2 In-Roof and Viridian Solar Clearline Fusion are all used on UK new builds. The right one depends on the tile profile, the roof pitch and whether the plot is in a conservation area.

Are in-roof systems watertight?

They are designed to be: in-roof trays use flashings and weatherings around the array. Ask the installer which system and flashing kit they use and follow the manufacturer’s installation instructions for the tile or slate profile.