UK commercial solar in 2026 costs between 700 pounds and 1,200 pounds per installed kilowatt depending on system size, roof complexity, and DNO requirements. That headline range conceals a lot of detail — twelve cost components stack up to make every project price, and getting any single one wrong by 20 percent shifts the project IRR by 1-2 percentage points. This page lays out every cost line item with current 2026 ranges, then walks through worked examples for 25 kW, 50 kW, 100 kW, and 250 kW installs, then explains the site-specific costs that genuinely vary (asbestos, three-phase upgrades, DNO reinforcement) and how to tell when an installer is hiding them in a low headline price.
The twelve cost components
Every UK commercial solar quote stacks the same twelve elements. Honest quotes break them out; hiding-something quotes bundle them. Here are 2026 ranges per kW of installed capacity.
1. Solar panels (modules)
Tier-1 mono PERC and TOPCon panels currently land at 0.15-0.25 pounds per Watt of capacity, or 150-250 pounds per kW. Brand premium matters: JA Solar, Trina, Longi cluster at the lower end (0.16-0.19 pounds per Watt); REC, Maxeon, SunPower at the upper end (0.22-0.25 pounds per Watt for premium long-warranty product). Bifacial panels add 5-15 percent on cost but deliver 5-15 percent yield uplift on appropriate (high-albedo) substrates so the economics often wash. For a 100 kW system, panels alone cost 15,000-25,000 pounds.
2. Inverters
String inverters run 0.08-0.15 pounds per Watt or 80-150 pounds per kW. Brand spread: Sungrow, Solis, Huawei at the lower end (0.08-0.10); SMA, Fronius at mid-range (0.10-0.13); SolarEdge with module-level optimisers at the upper end (0.13-0.17 pounds per Watt for the optimiser-included system). For a 100 kW string-inverter system: 8,000-15,000 pounds. SolarEdge with optimisers on every panel is closer to 16,000 pounds. Microinverters (Enphase) push the inverter cost to 0.20-0.25 pounds per Watt and we rarely specify them on commercial unless shading or aesthetics demands.
3. Mounting and racking
Roof mounting hardware (rails, clamps, fixings) costs 0.05-0.10 pounds per Watt or 50-100 pounds per kW. Pitched-roof rail systems (Schletter, K2, Renusol) cluster at the lower end. Flat-roof ballasted systems (Renusol Console, Van der Valk Ballastsupport) sit mid-range. In-roof systems (GSE In-Roof, IBC TopSky) used on listed buildings and conservation areas push to 0.10-0.15 pounds per Watt, a 50-100 percent premium versus standard rail. For a 100 kW pitched roof: 5,000-10,000 pounds for standard mounting.
4. DC cables, isolators, fuses
DC-side electrical components run 0.03-0.05 pounds per Watt or 30-50 pounds per kW. Includes string cables (typically 6 mm² solar cable), DC isolators per string, DC combiner boxes, surge protection, and earthing. For a 100 kW system: 3,000-5,000 pounds.
5. AC cables and switchgear
AC-side runs 30-60 pounds per kW depending on cable runs and switchgear specification. SWA cable from the inverter to the main distribution board, AC isolators, contactors, generation meter, export meter, lockable knife-switches per regulatory requirement. Long cable runs (over 50 metres) push to the upper end. For a 100 kW system: 3,000-6,000 pounds.
6. Labour (installation)
Labour typically lands at 15-25 percent of total project cost. For a 100 kW system at around 90,000 pounds total, expect 13,500-22,500 pounds of labour: roof-fitting electricians (the largest share), DC/AC cabling, switchgear and inverter commissioning, project management overhead. The mix is around 60 percent on-site labour, 40 percent project management and overhead.
7. Scaffolding and access
Scaffolding for commercial roofs runs 2,000-15,000 pounds depending on building height, complexity, and edge protection requirement. Single-storey warehouse: 2,000-4,000 pounds. Two-storey office: 5,000-9,000 pounds. Three-storey hotel with pedestrian protection: 10,000-15,000 pounds. Scaffolding stays up for the install duration (1-3 weeks sub-100 kW, 3-8 weeks 100-500 kW) and weekly hire rates apply.
8. Structural survey
A chartered structural engineer assesses whether the roof can take the additional 18-25 kg per square metre of panel and mounting load. Cost: 600-1,500 pounds for a competent survey. Below 30 kW some installers skip the formal engineer report and rely on a desk calculation; above 50 kW the structural survey is genuinely non-negotiable and the insurance position turns on it.
9. Asbestos survey (pre-2000 buildings)
Required by law for any building constructed before 2000 under the Control of Asbestos Regulations 2012. A management survey costs 400-900 pounds. If asbestos is present, a refurbishment and demolition survey costs 800-1,500 pounds and is required before any disturbance. We commission asbestos surveys at the desk-feasibility stage on every pre-2000 building because finding asbestos late wrecks programmes.
10. Design and engineering
System design (PVSyst yield modelling, single-line diagram, structural drawings, fixing detail, electrical schedule) costs 1,500-5,000 pounds depending on system size. On larger projects (over 250 kW) the design package is more complex and runs 5,000-15,000 pounds. Most installers include design in the headline price; on contract sites or project-managed builds it can be a separate line item.
11. DNO admin
G98 application fee for sub-100 kW: 0-150 pounds depending on DNO. G99 application fee for above: 350-15,000 pounds depending on capacity. G99 application admin and project management (our cost): typically built into the project price as 1,500-5,000 pounds for routine cases. See our G98 and G99 pages for the full process and timeline.
12. VAT
Standard 20 percent VAT applies to commercial solar PV in the UK. The zero-rated relief for domestic solar does not apply to commercial premises. VAT-registered businesses recover it through normal returns. We always quote ex-VAT and add VAT as an explicit line. See VAT on commercial solar.
Worked example 1: 25 kW small office or workshop
14-person professional services office in Leeds, single-storey rear extension to a Georgian terrace, 200 sqm flat roof. Panels: 66 x JA Solar 380W modules. Inverter: 1 x Sungrow SG25K3 at 25 kW. Mounting: Renusol Console flat-roof ballast.
- Panels: 25,000 W x 0.18 = 4,500 pounds
- Inverter: 25,000 W x 0.10 = 2,500 pounds
- Mounting: 25,000 W x 0.08 = 2,000 pounds
- DC components: 25,000 W x 0.04 = 1,000 pounds
- AC and switchgear: 25,000 W x 0.05 = 1,250 pounds
- Labour: 5,800 pounds
- Scaffolding: 2,500 pounds
- Structural survey: 800 pounds
- Asbestos survey (1980s building): 600 pounds
- Design and engineering: 1,500 pounds
- DNO (G98 connect-and-notify): 0 pounds
- Subtotal ex-VAT: 22,450 pounds
- VAT at 20 percent: 4,490 pounds
- Total: 26,940 pounds inc. VAT, or 1,078 pounds per kW
Worked example 2: 50 kW industrial unit
Light engineering business in 12,000 sqft single-storey shed in the West Midlands, 400 sqm pitched metal roof. Panels: 132 x JA Solar 380W. Inverter: 1 x SMA Sunny Tripower 50000 STP at 50 kW. Mounting: K2 Speed Rail on metal roof clamps. Building constructed 1998 — asbestos survey clear.
- Panels: 9,000 pounds
- Inverter: 5,500 pounds
- Mounting: 3,500 pounds
- DC components: 1,800 pounds
- AC and switchgear: 2,200 pounds
- Labour: 9,500 pounds
- Scaffolding: 3,500 pounds
- Structural survey: 1,000 pounds
- Asbestos survey: 750 pounds
- Design and engineering: 2,200 pounds
- DNO G98: 0 pounds
- Subtotal ex-VAT: 38,950 pounds
- VAT at 20 percent: 7,790 pounds
- Total: 46,740 pounds inc. VAT, or 935 pounds per kW
For deeper detail on this size band see 50kW solar system cost.
Worked example 3: 100 kW retail or hospitality
Garden centre in Surrey with 22,000 sqft sales floor and warehouse, 1,200 sqm flat membrane roof. Panels: 263 x JA Solar 380W. Inverter: 2 x Huawei SUN2000-50KTL at 100 kW total. Mounting: ballasted flat-roof. Three-phase 400 kVA supply available.
- Panels: 17,500 pounds
- Inverter: 9,500 pounds
- Mounting: 7,000 pounds
- DC components: 3,500 pounds
- AC and switchgear: 4,500 pounds
- Labour: 16,500 pounds
- Scaffolding: 4,500 pounds
- Structural survey: 1,200 pounds
- Design and engineering: 3,000 pounds
- DNO G99 (above 100 kW threshold, just): 2,500 pounds
- Subtotal ex-VAT: 69,700 pounds
- VAT at 20 percent: 13,940 pounds
- Total: 83,640 pounds inc. VAT, or 836 pounds per kW
For 100 kW deep-dive see 100kW solar system cost.
Worked example 4: 250 kW industrial scale
Precision engineering firm in 22,000 sqft industrial unit, West Midlands. East-west pitched roof 1,500 sqm. Panels: 658 x JA Solar 380W. Inverters: 4 x SMA Sunny Tripower 60000 at 240 kW (slightly under-sized to balance grid). Mounting: K2 metal-roof system. G99 application required.
- Panels: 42,000 pounds
- Inverters: 22,000 pounds
- Mounting: 16,000 pounds
- DC components: 9,000 pounds
- AC and switchgear: 11,000 pounds
- Labour: 35,000 pounds
- Scaffolding: 6,500 pounds
- Structural survey: 1,500 pounds
- Design and engineering: 7,500 pounds
- DNO G99 application + admin: 5,500 pounds
- Subtotal ex-VAT: 156,000 pounds
- VAT at 20 percent: 31,200 pounds
- Total: 187,200 pounds inc. VAT, or 749 pounds per kW
Site-specific costs that genuinely vary
Three-phase upgrade. A site on single-phase 60-100 A supply needs three-phase upgrade for any system above around 17 kW. Cost: 3,000-15,000 pounds depending on the DNO and the distance to the local feeder. Always identify at quote stage.
Asbestos roof replacement. Pre-2000 buildings with asbestos cement roofs typically need either specialist standoff mounting (30-50 percent uplift on mounting cost) or full roof replacement (40-100 pounds per square metre). On a 1,500 sqm shed that is 60,000-150,000 pounds — a project-defining number.
Structural reinforcement. Older steel-portal sheds with marginal purlin capacity sometimes need additional purlins or stiffeners to support PV load. Typical cost 30-60 pounds per square metre across the affected area, often 15,000-50,000 pounds on a typical industrial shed.
DNO network reinforcement. Constrained networks (urban London, Cornwall, parts of Scotland) sometimes quote 30,000-250,000 pounds for transformer or 11 kV cable reinforcement on G99 connections above 200 kW. Always run a DNO heat-map check at desk feasibility. See G99 application.
Battery storage. Optional, not mandatory. A 50 kWh commercial battery system costs around 35,000-55,000 pounds installed. For sites with significant export at low SEG rates and high import at peak times, batteries can lift project IRR by 2-4 points; for sites with already high self-consumption above 80 percent the case is weak. See battery storage.
Hidden costs to watch in low-headline quotes
Some installers price low headline by pushing standard cost lines into "extras" that materialise after contract. Watch for: scaffolding excluded from the headline ("budget allowance to be confirmed on survey"), structural survey excluded, asbestos survey excluded on pre-2000 buildings, DNO admin and application fees excluded, design and engineering excluded, three-phase upgrade excluded where the supply is single-phase. A reputable installer prices each of these as either a discrete line in the quote or a clearly-stated allowance — never a vague "extras to be confirmed."
The cost benchmarks that matter most
Two numbers tell you whether a quote is competitive. Total cost per kW: should land in the per-kW band for the system size (1,000-1,200 sub-50 kW, 850-1,000 50-100 kW, 750-900 100-500 kW, 700-850 500 kW+). Implied cost per kWh of lifetime generation: total project cost divided by 25 x annual generation should land at 4-8p per kWh. Above 8p the project struggles to pay back; below 4p there is something missing from the quote. We always show both numbers in our project DCF.
Authority resources
HMRC capital allowance rules (100 percent AIA on PV): gov.uk Capital Allowances. MCS for installer competency on sub-50 kW: MCS. Energy Networks Association on G98 and G99: ENA Distributed Generation. Ofgem on SEG export tariffs: Ofgem SEG.
Related decision pages
For the full ROI maths see solar panel ROI and are commercial solar panels worth it. For tax structure see capital allowances and VAT. For business rates relief see business rates. For finance routes see commercial solar finance and grants. For sector-specific cost guides see factories, warehouses, offices. For the DNO process at scale see G99 application.
Solar installation cost — common questions
How much does commercial solar installation cost in the UK in 2026?
For UK commercial solar, expect 900-1,200 pounds per kW for projects below 100 kW, 750-950 pounds per kW for 100-500 kW, and 700-850 pounds per kW for 500 kW and above. These are turnkey numbers including panels, inverters, mounting, DC and AC cabling, switchgear, design, scaffolding, install, commissioning, G98 or G99 admin, and standard warranties. They exclude three-phase upgrades, asbestos roof replacement, structural reinforcement, and major DNO network reinforcement, all of which are site-specific.
What does the labour element cost on a commercial solar install?
Labour typically lands at 15-25 percent of total project cost on a commercial install. For a 50 kW project at around 50,000 pounds total, expect 8,000-12,500 pounds of labour. The mix is roof-fitting electricians (most of the cost), DC/AC cabling, switchgear and inverter commissioning, and project management overhead. Labour costs scale sub-linearly with system size — doubling the system size does not double the labour, which is why per-kW pricing falls as systems grow.
Why is scaffolding so expensive on commercial solar?
Scaffolding for commercial roofs runs 2,000-15,000 pounds depending on building height, complexity, and required edge protection. A single-storey warehouse with a parapet might need only access scaffolding at 2,000-4,000 pounds. A three-storey hotel or office with multiple eaves levels and pedestrian protection at street level can hit 12,000-15,000 pounds. Scaffolding sits on the roof for the install duration (typically 1-3 weeks for sub-100 kW, 3-8 weeks for 100-500 kW) and weekly hire rates apply. We always quote scaffolding as a discrete line item to keep it visible.
Do I pay VAT on commercial solar installation?
Yes. Standard 20 percent VAT applies to commercial solar PV installations in the UK. The zero-rated VAT relief that applies to domestic solar (extended to 2027) does not apply to commercial premises. VAT-registered businesses can reclaim it through their normal VAT return. Partial-exemption businesses (e.g. educational establishments, charities) can reclaim only the proportion attributable to taxable supplies. See our VAT on commercial solar page for full detail.
What surveys do I need before a solar install and what do they cost?
Three surveys are typical. A structural survey (around 600-1,500 pounds) confirms the roof can support the additional 18-25 kg per square metre of panels and mounting. An asbestos survey (400-900 pounds) is required by law for any building constructed before 2000, even if previous surveys exist. A DNO supply check (free, desk-based) confirms phasing and Available Supply Capacity. On larger projects we also commission a roof condition report (250-500 pounds) and a comprehensive solar feasibility study (free if commissioned with a quote, 1,500-3,500 pounds standalone).
How does asbestos affect installation cost?
Asbestos cement roofs were standard on UK industrial buildings from the 1950s to the 1990s and are present on a significant share of pre-2000 sheds. Asbestos in good condition is generally safe in situ but becomes a legal disturbance issue once panel mounting penetrates it. Two routes: (1) leave asbestos undisturbed and use specialist standoff mounting at a 30-50 percent uplift on mounting cost, or (2) replace the asbestos roof with modern profiled steel at 40-100 pounds per square metre and install solar on the new roof. Replacement is often the right answer for sheds where the roof is end-of-life anyway, but it adds 30,000-150,000 pounds to a typical industrial project.
What is the difference between cost per kW and cost per kWh?
Cost per kW is the upfront capital cost divided by installed capacity (e.g. 50,000 pounds for a 50 kW system equals 1,000 pounds per kW). Cost per kWh is the lifetime cost of generation: total project cost divided by total energy generated over 25 years. For a typical UK commercial system, lifetime cost per kWh lands at 4-8p — well below the 24p+ retail import price. Cost per kW is what you negotiate with the installer; cost per kWh is what tells you whether the project pays back, and both should appear in any honest quote.