Commercial Solar Panel Cost UK 2026: Real Numbers by System Size
Up-to-date 2026 UK commercial solar costs by kW range. Real per-kW pricing, payback periods, AIA tax relief, financing routes. Honest numbers from MCS-certified installers.
If you have asked three different installers for a price and ended up with three wildly different quotes, you are not unusual. Commercial solar pricing in the UK is opaque on purpose — most quotes bundle scaffold, DNO fees, panels, inverters, monitoring, civils and margin into a single number, and the moving parts vary from site to site. This guide pulls those moving parts apart and gives you defensible per-kW ranges for 2026, plus three worked examples covering the bands most UK SMEs sit in.
If you want a fast indicative figure, our commercial solar cost calculator will get you in the right ballpark in two minutes. The numbers below are how the people building the calculator think about it.
Per-kW pricing in 2026: three bands, three economies
The cleanest way to read UK commercial pricing is by system size band, because labour, balance-of-system and DNO costs do not scale linearly. A 30 kW office roof and a 600 kW warehouse roof are not the same job done bigger.
| System size | Typical 2026 per-kW range (ex VAT) | Why this band exists |
|---|---|---|
| Sub-100 kW | £900 – £1,200 / kW | Domestic-style installation cost base, MCS sub-100 kW process, G98 connection (cheaper, faster). |
| 100 – 500 kW | £750 – £950 / kW | Commercial-grade racking, three-phase string inverters, G99 application required, larger crews and cranes. |
| 500 kW+ | £700 – £850 / kW | Utility-style economics, central inverters or large strings, often ground-mount or industrial roofs. |
These ranges assume a sound roof or sensible ground site, no specialist asbestos or structural remediation, MCS-certified installation, monitoring included, and a standard string inverter set-up without battery storage.
Battery storage is priced separately at roughly £400 – £700 per kWh of usable capacity in 2026 — see our commercial battery storage worth-it analysis for whether to add it.
What moves you up the band, what moves you down
Costs lean to the upper end of each band when:
- Roof access is awkward (mansard, pitched tile, narrow eaves, no roof anchor points).
- The site needs a G99 connection above 100 kW with a non-trivial DNO study.
- You specify Tier 1 panels, optimisers per panel, or premium monitoring (e.g. SolarEdge module-level + commercial portal).
- The site requires asbestos surveying, structural surveying, or a temporary roof.
- You sit in a high-cost labour market (London, M25 inner ring) where day rates are 15–25% higher.
Costs lean to the lower end when:
- The roof is large, flat, single-pitch and structurally sound (typical industrial unit, distribution centre, modern warehouse).
- You can take a Tier 1 mainstream module and a leading three-phase string inverter without specifying premium kit per-panel.
- Civils are minimal (no DNO transformer upgrade required).
- The project clears 250 kW+, where fixed costs amortise across more capacity.
Worked example 1: 50 kW office roof — £45,000 to £60,000
A 50 kW system roughly fits a 280 m² south-facing roof with no major shading. At £900–£1,200/kW the headline ex-VAT figure runs from £45,000 at the bottom of the band to £60,000 at the top. For an SME office in a 2,000–3,500 m² building this is the typical case.
Annual generation: roughly 47,500 kWh in central UK irradiance terms (around 950 kWh/kWp/year, varying by region — see our Manchester, Birmingham and Bristol location pages for regional kWh/kWp benchmarks).
Annual saving (cash basis): at a current 2026 commercial unit rate around 26p/kWh, with 70% self-consumption and the remaining 30% exported under SEG at 8p/kWh:
- Self-consumed: 33,250 kWh × 26p = £8,645
- Exported: 14,250 kWh × 8p = £1,140
- Total Year 1 saving: ~£9,785
Simple payback: at the £52,500 mid-band cost, around 5.4 years before factoring AIA. With AIA factored in (see below) the effective payback drops below 4 years for a profitable corporation-tax-paying SME.
Worked example 2: 200 kW industrial unit — £150,000 to £190,000
A 200 kW rooftop typically suits a single-storey industrial unit of around 1,200 m² roof area. At £750–£950/kW the band is £150,000 at the lower end and £190,000 at the upper end ex VAT. This is the most common size we see for solar panels for warehouses, factories and logistics businesses.
Annual generation: ~190,000 kWh/year.
Annual saving: if the operation runs a daytime 5-day week with 60% self-consumption and 40% export:
- Self-consumed: 114,000 kWh × 25p = £28,500
- Exported: 76,000 kWh × 7.5p = £5,700
- Total Year 1 saving: ~£34,200
Simple payback: ~5.0 years at the mid-band. After AIA at the 25% main rate of corporation tax, effective net cost drops by approximately £42,500 — pulling payback below 4 years.
Worked example 3: 800 kW ground-mount or large industrial roof — £560,000 to £680,000
An 800 kW system is typically either a large logistics shed roof or a small ground-mount adjacent to a manufacturing site. At £700–£850/kW the headline range is £560,000 to £680,000 ex VAT. This sits firmly inside G99 territory and the DNO process becomes a meaningful part of the project plan.
Annual generation: ~760,000 kWh/year.
Annual saving: for a manufacturing site with 70% daytime self-consumption at a heavy-user contract rate around 22p/kWh:
- Self-consumed: 532,000 kWh × 22p = £117,040
- Exported: 228,000 kWh × 7p = £15,960
- Total Year 1 saving: ~£133,000
Simple payback: ~4.7 years at the mid-band, falling to around 3.5–4 years post-AIA for a profitable PLC. For an energy-intensive manufacturer this is one of the strongest cap-ex returns available in 2026.
AIA: the tax mechanic that changes everything
The Annual Investment Allowance lets you deduct 100% of qualifying plant and machinery cap-ex from taxable profits in the year of purchase. Solar PV qualifies. The AIA threshold has been £1m per annum since April 2023 and remains in place for 2026 — see HMRC’s capital allowances guidance for the current rules.
In practical terms: at 25% corporation tax, every £100,000 of qualifying solar cap-ex saves £25,000 in tax, paid back inside the first accounting period after commissioning. Our deeper guide is at commercial solar tax benefits in the UK, but the mental model is straightforward — your effective post-tax cost is roughly 75% of the headline price for a profitable business at the main CT rate.
Hidden costs the cheap quotes leave out
A “£700/kW” headline can balloon by 15–25% once the survey returns. The most common omissions:
- DNO connection costs — for a G99 application, connection charges from £1,500 to £80,000+ depending on local network constraint. Always ask if the DNO fee is included or pass-through.
- Roof works — purlin reinforcement, replacement of degraded roof sheets, asbestos R&D survey on pre-2000 buildings.
- Scaffold and fall arrest — on tall industrial units, scaffold can be £3,000–£15,000 alone.
- Half-hourly metering upgrade — required above 100 kW and for SEG export metering on most contracts.
- Specialist insurance — installer’s all-risk cover during construction often passed through.
- Monitoring and commissioning — some quotes exclude the commercial monitoring portal subscription beyond Year 1.
A clean quote breaks all of these out as line items, not lumps them into “balance of system”.
Install timeline: what to expect in 2026
For a sub-100 kW system on a straightforward roof, expect 6–10 weeks from contract to commissioning. Roof works typically take 5–10 site days plus DNO sign-off.
For 100–500 kW with a G99 application, 4–8 months end-to-end is realistic — the DNO study and connection offer is the dominant pole. Schedule the install around the offer rather than vice versa.
For 500 kW+, expect 8–18 months. DNO studies for grid-constrained areas (parts of the East of England, parts of the South East, the Welsh borders) regularly run 9 months alone before any cabling lands on site.
What good 2026 quotes look like — checklist
When you compare quotes, normalise them on these items before comparing the bottom line:
- Per-kW headline broken out separately
- Panel make and model, with Tier 1 status confirmed (Bloomberg NEF tier ranking)
- Inverter make and model, with warranty length stated
- DNO fee itemised (or stated as pass-through)
- Scaffold and fall arrest itemised
- Monitoring specified and warranty for monitoring access stated
- Workmanship warranty (10 years is standard, 25 years on panel power output)
- Insurance-backed warranty if installer is part of an IWA scheme
- MCS certification for the installation business (not just a certified employee) — verify on the MCS Certified database
If a quote is missing four or more of these, it is not a comparable quote.
When the maths actually says “yes”
The simplest test: if your business pays more than £30,000/year in electricity, has a south-facing or east-west roof of 200 m²+ in reasonable condition, runs a daytime load, pays UK corporation tax at the main rate, and is comfortable with a 4–6 year payback, commercial solar is almost always cap-ex positive in 2026.
Where the maths starts to wobble:
- Tenants without landlord co-operation (lease shorter than 7 years).
- Sites with a major DNO constraint and £80k+ connection cost.
- Operations that consume <30% of generation and rely heavily on export (SEG of 5–8p/kWh is below the import rate, so the more you export, the worse the unit economics).
The right answer for your specific case requires modelling against your half-hourly load. Get a tailored commercial solar quote and we will model it on your real consumption rather than a bill estimate.