Solar photovoltaic panels have become standard on new UK housing in response to Building Regulations Part L changes and Future Homes Standard direction. Most developer specifications now include PV on the majority of plots as the default rather than as an upgrade. That shift has practical implications for the roofing programme that are still being underestimated on many schemes.
The core issue is that PV integration changes the roofing scope. Panels sit on the roof, either integrated (replacing tiles) or applied (mounted on rails above the tiles). Cabling runs from the panels to the inverter. Roof penetrations are needed for cables. Fixings for the mounting system are made through the roof covering. Each is a roofing-adjacent activity that interacts with the underlay, the fixing schedule, and the wind uplift performance of the roof.
Where the roofing contractor and the PV installer are separate contractors coordinated by the developer or principal contractor, the interface has to be managed carefully. Which trade owns the roof penetration? Who is responsible for the weatherproofing at the mount points? Whose warranty covers water ingress that appears in the vicinity of a PV fixing? Each question needs a clear answer before either trade starts.
Where the answers are not clear, defects emerge and warranty conversations become adversarial. The PV installer says the water is coming through the roof, not through their fixings. The roofer says the water is coming through the fixings, not through the roof. The developer sits in the middle. The occupant is unhappy.
Globe Roofing's approach to schemes with PV is to establish the roofing/PV interface at pre-start rather than at first installation. Where the specification allows, we prefer to install PV mounting fixings ourselves as part of the roofing package, with the electrical connection made by the PV specialist afterwards. That approach places single-source responsibility for water tightness at the roofing package.
Where the developer prefers a separately-procured PV package, we specify the fixing points and the weatherproofing detail at design stage so that the PV installer is working to a documented spec rather than improvising on the day. The roofing warranty then explicitly covers the fixings we installed, with the electrical warranty covering the PV installer's work.
There is also a fixing-schedule interaction worth flagging. Roofs with PV panels experience different wind loading than roofs without. The panels present a larger sail area to horizontal wind, and the mounting system transfers that load into the roof structure. The tile fixing schedule needs to reflect this rather than assuming a bare roof.
On schemes where PV is being specified, the wind uplift calculation should include the panel loading. A tile fixing schedule that would have been adequate for a bare roof may be marginal for a roof with panels. Getting this wrong produces a scheme that passes NHBC inspection at handover but performs poorly in a serious wind event later.
For developers specifying PV as standard on housing schemes, the practical advice is to bring the PV interface into the roofing conversation at design stage rather than at construction stage. The cost of doing this is essentially zero. The cost of not doing it emerges as warranty defect claims across the first two years.
There is also a longer-term consideration. PV panels have a service life of twenty to twenty-five years, whereas the underlying roof is expected to last thirty to forty. At some point, the PV will be replaced while the roof continues. The replacement will require removal of the original fixings, which needs to be possible without compromising the roof. Designing for this eventuality at initial installation is not difficult if it is thought about. It is very difficult if it is not.
Talk to Globe Roofing
To discuss solar PV integration with your roofing programme on your scheme, contact Globe Roofing on 01223 890727 or email enquiries@theglobegroup.co.uk.
