"Is my roof suitable for commercial solar panels?" is the single most common pre-quote question UK business owners and finance directors ask. The good news: approximately 80% of UK commercial roofs are technically suitable for solar installation. The 20% that aren\'t typically face structural loading limits, asbestos cement roofing, or severe shading. This page covers the 8-factor suitability checklist used in our pre-quote desk feasibility, with good/acceptable/avoid criteria for each factor. For roof type deep-dive see commercial solar roof types; for mounting system overview see mounting systems.
The 8-factor commercial solar roof suitability checklist
Below is the complete 8-factor checklist used in our pre-quote desk feasibility. Each row shows the factor with good / acceptable / avoid criteria — score your roof against all 8 to determine overall suitability.
| Factor | Good | Acceptable | Avoid |
|---|---|---|---|
| Roof age | Less than 15 years old | 15-25 years (may need remediation) | Over 25 years (likely re-roof needed) |
| Roof material | Standing seam metal, modern profiled steel, EPDM/TPO membrane | Older profiled steel, concrete tile | Asbestos cement (pre-2000) — requires replacement first |
| Orientation | South-facing or east-west split (close to optimal) | SE/SW, E/W (90-95% of south yield) | North-facing primary only (not viable) |
| Pitch | 15-35° (peak yield range) | 5-15° or 35-45° (slight derating) | Over 60° (vertical walls are weaker for solar) |
| Shading | No shading 9am-4pm | Minor shading from rooftop plant | 4+ hours midday shading from adjacent buildings or trees |
| Structural loading | Modern steel-portal (post-2000) | Older steel-portal (structural engineer sign-off) | Lightweight steel without sufficient purlin capacity |
| Listed status | Unlisted commercial building | Grade II listed (rear elevations only) | Grade I or II* listed front elevations (high refusal rate) |
| Roof size | 500+ sqm unshaded contiguous area | 200-500 sqm | Less than 50 sqm (residential-scale only) |
Factor 1: Roof age
Roof age matters because solar panels typically have 25-30 year operational life. Installing solar on a roof with under 10 years of remaining structural life means costly panel removal + re-roof + panel reinstall around year 10-15 — destroying solar economics. Good (under 15 years old): roof should outlast first solar system lifecycle with margin. No remediation needed. Acceptable (15-25 years old): roof condition survey recommended; possible re-roof during system life. Avoid (over 25 years old): likely re-roof needed first. Combined re-roof + solar install at £40-£100 per sqm roof + £700-£1,200/kW solar. Combined business case typically still works on industrial buildings where roof replacement was overdue anyway.
Factor 2: Roof material
Roof material affects mounting system selection and installation complexity. Best (standing seam metal): S-5! clip-fix mounting penetrates nothing, fastest install, zero membrane warranty issue. Good (modern profiled steel, EPDM/TPO membrane): straightforward through-fix or ballasted mounting. Standard install. Acceptable (older profiled steel, concrete tile, slate): careful mounting design needed; slate requires expert solar installer experience. Avoid (asbestos cement, pre-2000): Cannot install directly. Must combine with re-roof first. Asbestos disturbance is HSE-regulated and dangerous. See roof types deep-dive.
Factor 3: Orientation
Roof orientation determines annual generation yield. Best (south-facing): optimal UK yield at 1,000-1,100 kWh/kWp annually. Best (east-west split): 90-95% of south yield but generation spread across the day for better self-consumption alignment. Good (SE/SW): 95-98% of south yield. Acceptable (E or W only): 85-92% of south yield — economics still viable. Avoid (north-facing primary roof only): less than 50% yield — typically not viable. Most modern commercial buildings have either south-facing pitched or large flat roofs suitable for east-west split — north-facing-only is rare in UK commercial.
Factor 4: Pitch
Pitch (slope angle) affects how panels receive direct sunlight. Best (15-35°): UK peak yield range — south-facing 30° pitch is theoretical optimum. Good (5-15° or 35-45°): slight derating but well within commercial economics. Acceptable (flat roofs, 0-5°): use ballasted east-west mounting at 10° tilt to recover 80-90% of pitched yield. Avoid (vertical walls, 60°+): wall-mounted solar is less efficient and harder to maintain — niche application only.
Factor 5: Shading analysis
Shading is the single most common reason for solar projects underperforming relative to PVSyst yield model. Good (no shading 9am-4pm): peak generation hours uninterrupted. Acceptable (minor rooftop plant shading): 5-10% yield loss — easily absorbed in commercial economics. Avoid (4+ hours midday shading from adjacent buildings or trees): 30-50% yield loss — usually makes commercial economics unviable. Module-level optimisers (SolarEdge) recover 8-15% of shaded-array performance but don\'t fundamentally fix severely shaded sites. We always conduct full shading analysis using Solmetric SunEye equipment as part of site survey.
Factor 6: Structural loading
Solar panels add 18-25 kg per sqm to roof loading. Most modern UK commercial buildings (post-2000) have substantial structural margin above design snow load (60-80 kg/m²) and accommodate solar without modification. Good (modern steel-portal post-2000): standard structural margin available. Acceptable (older steel-portal pre-2000): structural engineer\'s report recommended — typically £600-£1,500. Avoid (lightweight steel without sufficient purlin capacity, sagging roofs, deteriorated structure): requires structural reinforcement at £30-£60/sqm — usually destroys economics. We engage structural engineer for any building over 25 years old or where construction details are ambiguous.
Factor 7: Listed building or conservation area status
Listed buildings and conservation areas add planning complexity but rarely make solar impossible. Best (unlisted, non-conservation area): Permitted Development Rights apply, no planning needed for rear-facing roof installs. Acceptable (Grade II listed, rear elevations only): Listed Building Consent required (8-12 week determination). Sympathetic mounting design typically approves. Acceptable (conservation area): Planning permission needed for visible roof areas; rear roofs typically OK. Avoid (Grade I or II* listed front elevations): high refusal rate — front-facing installs rarely approved on heritage buildings. We have specific experience with listed building solar applications — see listed building solar + conservation area solar.
Factor 8: Roof size
Available unshaded roof area sets the maximum system size. Best (500+ sqm contiguous unshaded area): enough for substantial commercial install (100+ kW). Good (200-500 sqm): standard SME commercial sizing (50-180 kW). Acceptable (100-200 sqm): smaller commercial install (25-70 kW). Acceptable (50-100 sqm): very small commercial (10-25 kW) — smallest viable commercial install. Avoid (less than 50 sqm): residential-scale economics apply rather than commercial. Most modern UK commercial buildings have substantially more roof area than they need for sizing — structural and shading are typically binding constraints rather than raw area.
How to scoring your roof suitability
Add up your roof scoring across all 8 factors. All "Good" or "Acceptable": proceed with confidence to free desk feasibility — your roof is well-suited to commercial solar. 1-2 "Avoid" flags with manageable mitigation (e.g. structural engineer\'s report, listed building consent on rear elevations): proceed with desk feasibility while flagging the mitigation cost. 3+ "Avoid" flags: commercial solar economics will be challenging — submit anyway for an honest go/no-go recommendation, but be prepared for "not viable" answer. We routinely walk away from quotes where roof suitability is genuinely poor — it\'s better than committing to a project that won\'t deliver promised returns.
What if my roof has multiple flags?
Most UK commercial roofs have at least one factor that\'s "acceptable" rather than "good" — that\'s normal and doesn\'t prevent successful solar. Multiple factors at "acceptable" or one at "avoid" with clear mitigation usually still works. Examples we\'ve successfully delivered: (1) Older steel-portal warehouse with asbestos cement roof: combined re-roof + 250 kW solar at £550k total. Combined business case 6.5-year payback. (2) Grade II listed pub: 42 kW solar on rear-facing kitchen extension roof (avoiding listed core). Listed Building Consent approved in 9 weeks. 5.3-year payback. (3) East-west flat membrane roof with one shaded corner: 180 kW east-west ballasted array avoiding shaded zone. 5.8-year payback. Whether your specific situation works requires honest assessment.
Get a free roof suitability assessment
Our free 5-working-day desk feasibility includes a full roof suitability assessment. We use: building drawings (if you have them) or Google Earth satellite imagery, planning portal lookup for listed status + conservation area, ENA Connections portal for DNO constraints, sector load profile modelling. The report identifies any roof factors requiring remediation, prices the remediation, and delivers an honest go/no-go recommendation alongside the financial feasibility. Submit your annual electricity spend and site postcode below.
Commercial solar roof suitability — common questions
Is my commercial roof suitable for solar panels?
Approximately 80% of UK commercial roofs are technically suitable for solar panel installation. The 20% that aren't typically face one of three barriers: structural loading limitations (older steel-portal sheds without sufficient purlin capacity for the 18-25 kg/m² additional load), asbestos cement roofing (pre-2000 buildings requiring expensive re-roof before solar install), or severe shading (4+ hours midday shading reduces yield 30-50%, often making economics unviable). The remaining 80% of UK commercial roofs — modern steel-portal industrial, post-2000 flat membrane, standing seam metal, well-maintained pitched tile — are suitable with minimal remediation required. Free desk feasibility identifies suitability before any cost commitment.
What roof types are best for commercial solar panels?
The best UK commercial roof types for solar in 2026 are: (1) Standing seam metal roofs — fastest install with clip-fix mounting, zero roof penetration, lifelong structural integrity. (2) Modern profiled steel through-fix roofs — straightforward through-fix to purlins with EPDM sealing, standard install. (3) Flat single-ply membrane (EPDM, TPO, PVC) — ballasted east-west mounting preserves membrane warranty, ideal for warehouses and offices. (4) Sandwich panel insulated roofs (cold storage standard) — slightly more complex mounting due to insulation layer but very common in modern commercial. Less ideal: concrete tile (older offices, requires careful tile-hook mounting); slate (heritage buildings, expert installation needed); asbestos cement (requires replacement).
How much weight do solar panels add to a commercial roof?
Modern UK commercial solar panel arrays add 18-25 kg per square metre to roof loading — substantially less than the building's design snow load (typically 60-80 kg/m² across most UK regions). Most modern commercial buildings (post-2000) have sufficient structural margin to accommodate solar loading without modification. Older buildings (pre-1990) may require structural engineer's report to confirm capacity — typically £600-£1,500 site visit + analysis fee. Lightweight aluminium mounting frames (vs steel) reduce loading by ~30% for marginal structural cases. We always engage a structural engineer for buildings older than 25 years or where roof construction is ambiguous.
What roof orientation is best for commercial solar?
South-facing is technically optimal for UK commercial solar (peak generation yield 1,000-1,100 kWh/kWp annually) — but east-west split arrays achieve 90-95% of south-facing yield while delivering generation spread across the day (better self-consumption alignment for businesses with morning + afternoon load peaks). South-east and south-west facing achieve approximately 95-98% of due-south yield. East or west facing alone (single orientation) achieves approximately 85-92%. North-facing is not viable for UK solar (less than 50% yield, often net loss after capex amortisation). Most modern commercial buildings have either south-facing pitched roofs or large flat roofs suitable for east-west split installations.
Can solar panels be installed on asbestos cement roofs?
No — solar panels cannot be installed directly on asbestos cement roofs (common pre-2000 industrial buildings) because mounting work disturbs the cement and releases asbestos fibres, which is regulated under Health and Safety Executive (HSE) asbestos work prohibition for any non-licensed contractor. Two routes for asbestos roofs: (1) Combined re-roof + solar install — replace the asbestos roof with modern profiled steel or membrane (£40-£100 per sqm depending on building height and scaffolding) then install solar on the new surface. Combined business case typically delivers 5-8 year payback. (2) Over-sheet — lay a new metal roof skin on top of existing asbestos without removal. Cheaper at £25-£50 per sqm but adds load and requires structural engineer sign-off. We always recommend route 1 for safety, longevity, and warranty reasons.
What roof shading is acceptable for commercial solar?
Minor shading (rooftop plant, HVAC units, small chimney) reduces solar generation 5-10% — acceptable on commercial economics. Moderate shading (single tall building adjacent, large rooftop plant) reduces generation 15-25% — economics weaken but still typically viable. Severe shading (4+ hours of midday shading from adjacent buildings, trees, or large rooftop structures) reduces generation 30-50% — usually makes commercial economics unviable. We always run shading analysis as part of site survey using Solmetric SunEye or equivalent equipment. Module-level optimisers (SolarEdge) recover 8-15% of shaded-array performance but don't make severely shaded sites suddenly viable. Heavily shaded sites should not commit to solar without honest shading-modelled feasibility.
What's the minimum roof size for commercial solar?
Practical minimum roof area for UK commercial solar is approximately 50 sqm (sufficient for a 10 kW system with ~18 panels at 540W — smallest viable commercial install in 2026). Below 50 sqm available unshaded roof area, residential-scale solar economics apply rather than commercial. For practical SME commercial sizing: 100 sqm → 25-35 kW (small office); 250 sqm → 50-90 kW (SME industrial); 500 sqm → 100-180 kW (medium commercial); 1,000 sqm → 200-360 kW (large commercial); 5,000+ sqm → 1 MW+ (industrial scale). Most modern UK commercial buildings have substantially more roof area than they need for typical sizing — structural capacity and shading are usually the binding constraints rather than raw roof area.