Commercial rooftop solar installers deliver large-scale (typically 50 kW to 5 MW+) photovoltaic systems on existing commercial buildings — warehouses, distribution centres, factories, cold storage, retail, hotels and offices. Rooftop solar differs from ground-mount in installation methodology, planning rules, and structural assessment requirements. This page covers what to look for in a commercial rooftop solar installer, how rooftop solar works across different building types, and what installation costs and paybacks look like for typical UK commercial rooftop projects in 2026.
What commercial rooftop solar installers actually do
Commercial rooftop solar installation is a multi-discipline project covering structural assessment, electrical design, DNO grid connection, planning consultation, system supply and installation, and ongoing operation. Specifically: (1) Structural survey by Chartered Engineer assessing roof load capacity against UK National Annex Eurocode 1 wind and snow loads. (2) Electrical design specifying inverter topology (string vs central), AC/DC cabling, switchgear, monitoring. (3) G99 grid connection application to local DNO with technical study and connection offer process. (4) Planning consultation — most commercial rooftop solar is Permitted Development but listed buildings, AONB and conservation areas require formal consent. (5) Procurement and on-site installation typically 6-12 weeks for 500 kW - 2 MW systems. (6) Commissioning, monitoring activation, customer audit pack handover.
Rooftop solar by building type — methodology differences
Different commercial building types require different rooftop solar methodologies. Warehouses (steel portal frame, 5,000-25,000 sqm clear span): typical 500 kW - 5 MW systems, ballasted or clamp-on mounting depending on roof material. Factories (mixed steel/concrete, multiple bay heights): 250 kW - 3 MW systems, often phased install across bays. Cold storage (insulated steel portal frame): 500 kW - 2 MW systems, non-penetrating mounting essential to protect vapour barrier. Retail and supermarket (flat membrane roof, rooftop plant): 100 kW - 1 MW systems, careful plant equipment coordination. Office buildings (flat membrane or pitched tile): 50 kW - 500 kW systems, often building-integrated PV consideration. Hotels (mixed roof types, listed building considerations common): 50 kW - 250 kW systems with heritage sensitivity. We have delivered all commercial building types since 2010.
Commercial rooftop solar installation cost by system size
Costs scale with system size — per-kW cost decreases at larger scale. 100 kW: £850-£1,050/kW = £85,000-£105,000. 250 kW: £800-£1,000/kW = £200,000-£250,000. 500 kW: £750-£950/kW = £375,000-£475,000. 1 MW: £700-£800/kW = £700,000-£800,000. 2 MW: £700-£750/kW = £1,400,000-£1,500,000. 3 MW: £650-£720/kW = £1,950,000-£2,150,000. 5 MW+: £600-£700/kW. Cost includes MCS-certified panels (typically 435-550W bifacial modules), inverters, mounting, AC/DC cabling, monitoring platform, DNO connection works, structural assessment, planning where required, commissioning and 12-month warranty.
Mounting systems — by roof material
Rooftop solar mounting depends on roof material. Standing seam metal roof (Kingspan, Tata, Cembrit, Joris Ide): non-penetrating clamp-on mounting (S5! clamps and equivalent), zero penetrations, fastest install, lowest install cost. Trapezoidal profile metal roof: penetrating fastener systems with EPDM gasket sealing. Profile metal roof: continuous run rail with penetrating fixings. Ballasted flat membrane (PVC, EPDM, single-ply): non-penetrating ballast tray system, ballast weight per sqm calculated for wind uplift. Composite panel roof: penetrating fasteners through panel into substructure. Concrete (uncommon on warehouses, common on offices): bolted bracket fixed to concrete. Asbestos cement roof: requires overlay system or full re-roof first — never direct fixing.
National coverage — UK regional installation teams
We deliver commercial rooftop solar across all UK regions with consistent install quality. London + South East (UKPN DNO): Park Royal, Heathrow, Greenwich, Slough. Solent + South Coast (SSEN): Southampton, Portsmouth, Solent Freeport. East of England (UKPN): Felixstowe, Norwich, Cambridge, Peterborough. East Midlands (WPD/NGED, NPG): Magna Park, DIRFT, Northampton, Leicester. West Midlands (WPD/NGED): Birmingham, Coventry, Black Country. South West (WPD/NGED): Bristol, Exeter, Plymouth. Wales (WPD/NGED): Cardiff, Newport, Swansea, Wrexham. North West (ENW, SPEN): Manchester, Liverpool, Preston. Yorkshire + North East (NPG): Leeds, Sheffield, Hull, Newcastle. Scotland (SSEN, SPEN): Edinburgh, Glasgow, Aberdeen. Multi-site portfolios coordinated centrally with regional install teams.
Common questions about rooftop solar installers
Who are commercial rooftop solar installers?
Commercial rooftop solar installers are MCS-certified PV specialists delivering large-scale systems (typically 50 kW to 5 MW+) on existing commercial buildings including warehouses, factories, distribution centres, cold storage, retail and offices. Different to residential installers — commercial work requires G99 grid connection process, Chartered Structural Engineer sign-off, Insurance-backed Warranty cover, and customer Scope 3 audit pack capability.
How much does commercial rooftop solar cost in the UK?
Per-kW costs decrease with system size. 100 kW: £85-£105k. 250 kW: £200-£250k. 500 kW: £375-£475k. 1 MW: £700-£800k. 2 MW: £1.4-£1.5m. 3 MW: £1.95-£2.15m. 5 MW+: £600-£700/kW. Cost includes MCS panels, inverters, mounting, cabling, monitoring, DNO connection works, structural assessment, commissioning.
What roof types are suitable for rooftop solar?
Most modern UK commercial roofs are suitable. Standing seam metal (clamp-on mounting), trapezoidal/profile metal (penetrating fasteners), flat membrane PVC/EPDM (ballasted system), composite panels (penetrating through panel). Asbestos cement roofs require overlay or full re-roof first. Pre-1970 truss roofs may need structural reinforcement. We assess your specific roof during initial feasibility.
Do commercial rooftop solar installers work nationally?
Yes — we deliver across all UK regions including London + South East, Solent, East of England, East Midlands, West Midlands, South West, Wales, North West, Yorkshire + North East, Scotland and Northern Ireland. Multi-site portfolios coordinated centrally with regional install teams. Consistent install quality and consolidated audit reporting across all sites.
How long does commercial rooftop solar installation take?
End-to-end timeline 8-14 months from feasibility to energised system. Feasibility: week 1. Structural and electrical survey: weeks 2-3. G99 grid connection: weeks 3 to 6 months (parallel with planning). On-site installation: 6-12 weeks for 500 kW - 2 MW system. Commissioning and grid connection: 4-8 weeks. Constrained networks (central Manchester, West London, M25) can extend total timeline to 14-24 months.
Why use commercial rooftop solar installers vs residential?
Five key differences. (1) MCS Commercial vs Domestic certification — required for commercial systems above 11 kW and for grant funding. (2) G99 grid connection process (formal DNO study) vs G98 installer notification. (3) AIA / ECA / IETF grants vs residential SEG only. (4) Chartered Structural Engineer sign-off vs domestic permitted development. (5) Customer audit pack for B2B Scope 3 supply chain vs no audit requirement domestic.