The short answer
Solar panels can be fitted to natural slate using stainless steel brackets that are fixed to the rafters, passing through or between the slates, with the slates cut or flashed around them. The main risks are cracked slates, leaks around the fixings, and fitting panels to a roof that needs repairs soon. Fix the roof first if it is tired.
How panels are held on a slate roof
On a tiled roof, installers often use hooks that slide under tiles. Slate is thinner and more fragile, and the surface is flat, so the method differs. Common systems use a bracket or a hook, called a roof hook or slate hook, with a base plate that sits on the rafter and a stem that rises through a gap in the slate course. The panel rails then bolt onto the stems.
The slates around each fixing are cut or drilled so the stem passes through, and the joint is sealed with lead or a purpose-made flashing, so water runs over it and not into it. Done well, the fixing is tight and the slate lies flat. Done badly, the slate cracks under the bracket or the flashing leaves a gap.
The rails and brackets must land on the rafters, not the battens or boards, because the load is wind uplift as much as weight. Your installer should locate the rafters from the loft before marking the slope.
Weight and the roof structure
Panels and rails add weight, though less than a heavy covering. Natural slate is already heavy, and an old roof frame has carried it for decades. Add panels and the structure takes the extra load, plus wind uplift on the array. Before a roof is loaded, someone should check the rafters, purlins and any previous alterations.
Approved Document A, written with re-covering in mind, treats a rise in roof loading of more than 15 per cent as significant. That is a Building Regulations point rather than a planning one. The Planning Portal puts it as 15 per cent or more. A structural check is the safe route if the frame looks tired.
Planning rules for solar installations are separate from re-roofing. Where the house is listed or sits in a conservation area, ask Swindon Borough Council's planning team first.
Cracked slates and leaks around fixings
The common risk is breakage. Slates crack when walked on, when a bracket pinches them, or when they are lifted without care. Every cracked slate is a leak path and must be renewed. Our page on walking on slate explains why a roof is so easy to damage.
The second risk is the fixing itself. Every hole through the covering is a place where water can enter, and the flashing around it has to be right. A leak from a bracket flashing often shows weeks or months later and can look like a slipped slate, which is why the position of each fixing should be recorded.
Ask the installer how they replace broken slates, whether they use matching reclaimed slate, and whether they photograph the roof before and after. A cheaper installer who does not carry spare slates may leave cracks behind.
Is the roof ready for panels?
Panels last a long time, and the roof beneath should last at least as long. If the slates are slipping, the nails are corroding or the felt has perished, fixing panels on top means taking them off again for repairs, which adds scaffold and labour. MyBuilder's guide, updated in August 2026, gives around £850 to £1,200 for scaffolding an ordinary two-storey house, so erecting it twice is costly.
Nail fatigue is the usual hidden problem. Our page on nail sickness explains the signs. A roof that needs re-fixing or re-slating should be dealt with before panels go on.
If you are planning both, it is more economical to schedule the roof work first, then the panels, with the same scaffold if possible. Our guide to slate lifespan will help you judge.
Victorian slate and older buildings
On older houses, slates are often thinner and laid in a way that makes drilling difficult. A Victorian terrace can have slates that are fragile, with nails that have been in place for generations. Fixing panels on such a roof needs more care and sometimes some re-slating around the fixings. Our page on Victorian slate roofs covers their features.
Where a roof is in a conservation area or listed, panels may be restricted. The Railway Village in Swindon, for example, is covered by an Article 4 direction, and the council's appraisal says aerials and dishes on roofs are resisted. Always check with the council before you design a scheme.
Where panels are allowed, placing them on a rear slope that is out of public view is common. A south-facing rear slope may be a good compromise.
Questions to ask and what we do
Ask the installer which fixing they use on slate, how they locate rafters, who replaces any broken slates, how they flash each bracket, and what guarantee covers the roof as well as the panels. If they have not done slate before, find someone who has.
Our part is the roof underneath and around the array. That includes checking whether the roof is ready, re-fixing or re-slating first, and repairing flashings or slates after an installer has finished. Pictures from our survey and a written quote come before any work, and the finished job is guaranteed for ten years in writing.
If you are weighing the covering as well, our page on slate hanging covers vertical slate. To book, ring 01793 626096 or message us on WhatsApp. The wider slate roofing page lists our slate work.