FAQ: Integrating Solar Panels on Overclad, Refurbished or Repaired Roofs

Solar viability is primarily driven by energy consumption, rather than the roof condition alone.

As a general guide, solar becomes commercially attractive where a building is spending £60,000 or more per year on electricity. Higher on‑site consumption allows more of the generated power to be used directly. This improves financial performance and reduces reliance on export to the grid.

In addition, a site will typically need a minimum of 1,000 sqm of suitable, unshaded roof space with appropriate structural capacity (which can be factored into roofing works), and orientation. Even a newly refurbished roof may not meet these requirements if energy demand is too low or the usable roof area is limited.

For this reason, roof condition assessments with potential solar suitability, should always be combined with energy analysis.

Yes. Overclad roofs, whether metal, asbestos, fibre‑cement or composite, can accommodate solar integration when structurally assessed and designed correctly. Modern solar‑overclad systems apply a new watertight layer over the existing roof and can incorporate solar modules directly on to the new surface.

Under UK Building Regulations, adding solar panels is classed as “Installation of a Controlled Service or Fitting” and often a “Material Alteration” due to added load. Structural suitability must therefore be confirmed.
Solar panels typically add around 20 kg/m², which can represent up to a 15% increase in roof loading, triggering Part A compliance requirements.
MCRMA guidance stresses that ageing roofs should be surveyed by specialists to assess fragility, load capacity, wind loads and compatibility of mounting systems before any PV retrofit is approved. [labc.co.uk] [mcrma.co.uk]

Usually, yes. The Planning Portal confirms that the existing roof’s ability to carry the solar load must be checked, and strengthening work may be required.
Compliance with structural safety, electrical safety and ventilation requirements is also mandated under Building Regulations.
However, many accredited installers can self‑certify installations under a Competent Persons Scheme (CPS), provided their scheme covers the relevant Building Regulations parts. [planningportal.co.uk] [sunsave.energy] [labc.co.uk]

In most cases, solar panel installations on existing roofs fall under permitted development and do not require planning permission, (unless the building is listed or in a conservation area).
However, changes in appearance from overcladding may trigger planning requirements, so a pre‑check with the local planning authority is recommended. [renewablee…yhub.co.uk] [mcrma.co.uk]

Yes. Overcladding presents an ideal opportunity to integrate solar because:

• The building is already undergoing structural improvement.
• Insulation upgrades can be incorporated beneath the new external layer.
• The overclad layer can be designed to support and weatherproof solar components from the outset, improving long‑term performance and aesthetics.
• Lower access costs though scaffold/craneage already being on site for the overclad works, will reduce the cost of supplementary hire for PV installation.

With appropriate system design, yes, it could be possible. Overclad solar systems allow PV to be applied to otherwise fragile roofs, including asbestos sheet roofs, by creating a new load bearing structure above the original surface. This new structure can isolate the risk as well as provide a new surface to support a PV system.

When installed correctly using certified mounting systems, retrofitted PV should not compromise waterproofing. Historic England guidance emphasises that mounting details must avoid disrupting tiles, slates, or roof membranes to prevent moisture ingress.
[historicen…and.org.uk]

Yes. Modern commercial systems often use B Roof (t4) fire‑rated solar panels to meet stringent safety and insurance requirements. For systems including battery storage, Zurich Insurance guidance highlights the need for fire‑rated compartments and safe management of lithium‑ion battery risks (e.g., thermal runaway). [zurich.co.uk]

Wind uplift is a critical factor, especially on large metal roofs or in coastal/windy areas. MCRMA recommends confirming mounting system compatibility, strength testing, and assessment of positive/negative wind loads during design.
Certified systems designed specifically for overcladding provide high wind load performance across UK regions. [mcrma.co.uk]

Yes, if the roof is structurally sound. If only small repairs are needed and the roof retains adequate loading capacity, solar can be added as long as structural integrity and waterproofing are validated. Historic England guidance emphasises assessing condition of tiles, battens, anchors, and underlay before any installation. [marley.co.uk]

Very little. Overcladding typically allows installation without removing the original roof, drastically reducing disruption to operations. Solar systems are designed to be installed efficiently while the building remains in use.