Commercial Solar Cost per Watt UK 2026
UK commercial solar installs at £0.65–£1.10 per watt (£650–£1,100/kWp) in 2026. Full price breakdown by system size, sector and what affects the rate.
Quick Answer
What is the installed cost per watt for commercial solar in the UK?
The installed cost per watt for commercial solar in the UK in 2026 is £0.65-£1.10/Wp (£650-£1,100/kWp), depending on system size. A 10kW system costs approximately £1.00/Wp installed; a 100kW system costs £0.70-£0.80/Wp; a 500kW+ ground-mount system can reach £0.65/Wp. AIA tax relief reduces the effective cost by approximately 25% in Year 1 for most UK companies. All costs are ex-VAT (0% VAT applies to commercial solar).
Commercial solar cost per watt is the most useful single metric for comparing quotes and benchmarking installer pricing. In 2026, UK commercial solar installations range from £0.65 to £1.10 per watt-peak (Wp) fully installed — or expressed as £650 to £1,100 per kWp. The wide range reflects real differences in system scale, component quality, site complexity, and installer margin.
£0.65/Wp
Best Price (1MW+)
£0.75/Wp
Typical 100–500kW
£0.90/Wp
Typical 10–50kW
25% AIA
Tax Relief Year 1
Commercial Solar Cost per Watt by System Size (2026)
| System Size | Cost/Wp (Gross) | Cost/kWp (Gross) | Total Cost | After AIA (25%) | Annual Saving* |
|---|---|---|---|---|---|
| 10kW | £1.08 | £1,080 | £10,800 | £8,100 | £2,900 |
| 25kW | £0.96 | £960 | £24,000 | £18,000 | £6,700 |
| 50kW | £0.86 | £860 | £43,000 | £32,250 | £13,000 |
| 100kW | £0.75 | £750 | £75,000 | £56,250 | £25,000 |
| 250kW | £0.70 | £700 | £175,000 | £131,250 | £60,000 |
| 500kW | £0.67 | £670 | £335,000 | £251,250 | £118,000 |
| 1MW | £0.65 | £650 | £650,000 | £487,500 | £234,000 |
*Annual saving based on 1,050 kWh/kWp/yr irradiance, 85% self-consumption, 27p/kWh grid rate. Actual results vary by site, location and consumption profile. Request a site-specific model.
What £/Wp Actually Includes
A properly quoted commercial solar price per watt includes:
- Solar panels (Tier 1 manufacturer — typically Jinko Solar, JA Solar, Canadian Solar, or LONGi)
- Inverters (string inverters for <100kW; central inverters or multiple string units for 100kW+)
- Mounting system (ballasted for flat roofs; penetrating brackets for metal profile/concrete tile/asphalt; ground anchors for ground-mount)
- DC and AC cabling, isolators, and fuse protection
- G98/G99 DNO application and notification
- Monitoring system (cloud-based portal, 12-month subscription)
- MCS-compliant commissioning and documentation pack
Items typically not included in per-watt quotes and billed separately:
- Structural surveys and any required roof strengthening
- Scaffolding (varies significantly by building type and height)
- Electrical consumer unit upgrades
- DNO connection fee for G99 applications requiring upgrade works
- Battery storage (quoted separately)
Cost per Watt by Roof Type
| Roof Type | Cost Adder/kWp | Notes |
|---|---|---|
| Flat (membrane/felt) | +£0 | Ballasted system, lowest cost. Structural check required for >12° tilt. |
| Metal profile (Kingspan/Corus) | +£20–40 | Trapezoidal brackets. Fast install. Check liner integrity first. |
| Concrete tile | +£40–70 | Hook-and-rail system. Common on 1990s–2000s industrial units. |
| Fibre cement (non-asbestos) | +£40–80 | Requires specialist brackets. Fragile — careful access planning essential. |
| Asbestos-containing | +£80–200+ | Requires asbestos survey. Options: overlay system or re-roof + solar. |
| Ground-mounted | +£60–120 | Higher groundwork cost but optimal orientation and tilt possible. |
How to Evaluate a Commercial Solar Quote per Watt
When comparing commercial solar quotes, look beyond the headline price per watt and check:
- What is the panel manufacturer and power rating? A quote at £0.68/Wp using 420W Tier 2 panels and a budget string inverter is not comparable to a £0.75/Wp quote using 460W Tier 1 panels and a Sungrow hybrid inverter. The cheaper-per-watt system will likely underperform and fail sooner.
- Is the structural survey included? A low headline price that excludes structural assessment can balloon when the surveyor finds remedial roof work is required.
- What is the inverter warranty? Standard is 5–10 years. Extended warranties to 25 years are available and worth paying for on a 25-year asset.
- Is DNO notification included? For systems above 16A/phase (roughly >12kW), a G98 or G99 notification to the Distribution Network Operator is mandatory. This should be included in every commercial quote.
- Does the installer hold current MCS certification? Only MCS-certified installations are eligible for Smart Export Guarantee payments. Verify at mcscertified.com before signing.
Frequently Asked Questions
What is the commercial solar cost per watt in the UK in 2026?
Commercial solar installation costs in the UK in 2026 range from £0.65 to £1.10 per watt (peak), or £650 to £1,100 per kWp installed. Larger systems (250kW+) achieve economies of scale, typically landing at £0.65–£0.80/Wp. Smaller systems (10–50kW) range from £0.90–£1.10/Wp. Roof complexity, structural work, and DNO connection fees are additional.
How does cost per watt compare to cost per kWp?
Cost per watt and cost per kWp measure the same thing — just at different scales. 1 kWp (kilowatt-peak) = 1,000 Wp (watt-peak). So £0.75/Wp = £750/kWp. For a 100kW (100,000Wp) system at £0.75/Wp: total cost = £75,000. Most UK commercial solar quotes are expressed in £/kWp. Cost per watt is more commonly used in the US market but is equivalent.
What affects commercial solar cost per watt?
Key factors: system scale (larger = cheaper per Wp), panel tier (Tier 1 vs budget), inverter technology (string vs central vs hybrid), roof type (flat ballasted vs pitched penetrating vs ground-mount), structural reinforcement requirements, DNO connection type (G98 vs G99), and geographic location (remote sites have higher installation labour costs).
What is a good price per kWp for commercial solar in 2026?
A competitive 2026 commercial solar price in the UK is £680–£780 per kWp for a 100kW system with Tier 1 panels, quality inverters, and a 10-year workmanship warranty. Prices below £600/kWp should be scrutinised carefully — they often reflect budget components or exclude necessary structural surveys and connection fees. Always request a fully itemised quote.
How do I calculate commercial solar ROI from cost per watt?
Simple method: (Annual kWh generated × electricity rate) ÷ total system cost = annual return rate. Example: 100kW system at 1,050 kWh/kWp/yr = 105,000 kWh/yr. At 27p/kWh self-consumed = £28,350/yr saving. System cost £75,000. Annual return = 37.8%. Simple payback = £75,000 ÷ £28,350 = 2.6 years gross (before AIA). After 25% AIA tax relief, net cost = £56,250, payback = 2.0 years.
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Commercial Solar Cost Per Watt 2025: Full UK Benchmarks
UK commercial solar costs are typically quoted as a cost per kWp (kilowatt-peak) installed, which equates to £/Wp × 1,000. The installed cost per kWp varies significantly by system size, location, roof type, mounting system and inverter specification. Key benchmark ranges for 2025:
- 10-50kWp: £900-£1,200/kWp installed — small commercial rooftop systems. Higher per-unit cost due to lower economies of scale on scaffolding, electrical work and project management
- 50-100kWp: £800-£1,000/kWp installed — medium commercial. The sweet spot for cost-efficiency on most commercial roof types
- 100-500kWp: £700-£900/kWp installed — large commercial rooftop. Best economies of scale for standard trapezoidal steel roof installations
- 500kWp-2MWp: £600-£800/kWp installed — large commercial/ground-mounted with standard site conditions
- 2MWp+: £500-£700/kWp installed — utility-scale ground-mounted, major DCs, industrial parks
These £/Wp figures include all installed costs: panels, inverters, mounting systems, DC and AC cabling, switchgear, metering, commissioning and project management. They exclude battery storage, DNO reinforcement contributions, planning fees and building warrant fees. For accurate budgeting, always use an installed cost quote from a site-surveyed proposal rather than headline £/Wp benchmarks.
Does the cost per watt change for flat roofs vs pitched roofs?
Flat commercial roofs (ballasted or fixed low-pitch mounting systems) are typically £50-£100/kWp cheaper than pitched roof installations for equivalent system sizes. Ballasted flat-roof systems require no roof penetrations, use faster installation methods and avoid the scaffold uplift cost of pitched roof installations. However, ballasted systems add significant roof load (additional 30-50 kg/m²) and require a structural engineer's confirmation. Pitched roof installations on trapezoidal steel cladding (the most common commercial roofing type) use hook clamp systems that are lightweight and rapid to install.
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Get a Free QuoteGetting an Accurate Commercial Solar Cost
The only accurate way to cost a commercial solar installation is from a site-surveyed proposal. Headline £/Wp benchmarks should be used only for initial budget estimates — actual costs vary by 20-40% from the benchmark depending on roof access (scaffold vs MEWP vs rope access), electrical infrastructure condition (board capacity, earthing, metering), DC cable run length (roof to plant room), DNO connection type, planning requirements and local labour rates.
Our commercial solar proposals are fully detailed: panel supply, inverter supply, mounting hardware, DC and AC cabling, switchgear, metering, commissioning, DNO notification management, project management and 5-year workmanship warranty — all included in a single price with no hidden extras. Contact us today for a free site survey and detailed cost proposal for your commercial solar installation. Surveys are typically completed within 5 working days of enquiry.
All commercial solar prices quoted in our proposals are fully inclusive — no surprises at invoice stage. Our proposals show cost per kWp, total system cost, post-AIA net cost and LCOE so you can compare alternatives on a genuinely like-for-like basis. Contact us today for a free, fully detailed commercial solar cost proposal.
Accurate budgeting for commercial solar requires a site-specific quote rather than benchmark ranges. Contact us today for a free, fully itemised commercial solar cost proposal for your premises — typically delivered within 5 working days of a site survey.
All our commercial solar installations are quoted on a full supply-and-install basis with a fixed price — no variable labour charges, no materials uplifts. The quoted cost per kWp includes panels, inverters, mounting, cabling, switchgear, commissioning, DNO notification and project management. Contact us today for a site-specific proposal.