Commercial Solar Cost Per kW & Per Square Metre (2026 UK Breakdown)
How much is commercial solar per kW and per m² in 2026? Real UK per-kW pricing by system size, roof area needed, cost per square metre, and an itemised £/kW breakdown.
Commercial solar in the UK costs roughly £750 to £1,050 per kW installed in 2026, and the per-kW price falls as the system gets bigger — from around £1,050/kW on a 30 kW office roof down to about £750/kW on a 1 MW industrial array. Measured against roof area, that works out at roughly £110 to £160 per square metre of usable roof covered, because a commercial system needs about 6 to 7 m² of roof per kW installed. Those three numbers — per kW, per m², and roof area per kW — are all describing the same job from different angles, and this guide normalises them so you can sanity-check any quote you have been handed.
If you already have a figure and just want to see how it compares, our commercial solar costs page runs the same maths interactively. The tables below are the reference set the calculator is built on.
How much does commercial solar cost per kW in 2026?
Per-kW price is the single most useful way to compare quotes, because it strips out system size and lets you line up a 50 kW job against a 500 kW one on equal terms. The reason bigger systems are cheaper per kW is that a large share of the cost — design, scaffold mobilisation, DNO paperwork, commissioning, project management — is broadly fixed regardless of size, so it amortises across more capacity as the array grows.
| System size | Typical 2026 cost per kW (ex VAT) | Indicative total (ex VAT) |
|---|---|---|
| 30 kW | ~£1,050 / kW | £31,500 |
| 50 kW | ~£980 / kW | £49,000 |
| 100 kW | ~£900 / kW | £90,000 |
| 250 kW | ~£820 / kW | £205,000 |
| 500 kW | ~£780 / kW | £390,000 |
| 1 MW (1,000 kW) | ~£750 / kW | £750,000 |
These are turnkey ranges for a sound roof, MCS-certified installation, standard Tier 1 modules and string inverters, monitoring included, and no battery storage. Add roughly £400–£700 per kWh of usable capacity if you are specifying a commercial battery. For a deeper walk-through of a single size, the 100kW solar system cost page models generation, self-consumption and payback in detail.
What does the £/kW actually pay for? (itemised breakdown)
A “£900/kW” headline is really six cost centres stacked on top of each other. Breaking a 100 kW system into its component per-kW costs shows where the money goes and which lines a cheaper quote tends to quietly omit.
| Cost component | Approx. £/kW | Share of total |
|---|---|---|
| Panels (modules) | £260 | ~29% |
| Inverter(s) | £105 | ~12% |
| Mounting & racking | £115 | ~13% |
| Electrical, cabling & DNO | £150 | ~17% |
| Installation labour, scaffold & commissioning | £215 | ~24% |
| Design, monitoring & project management | £55 | ~6% |
| Total | £900 | 100% |
The two lines that vary most between sites are electrical/DNO and installation/scaffold. A constrained grid connection that needs network reinforcement can push the DNO line from a few hundred pounds to tens of thousands, and a tall or awkward roof can double the scaffold element. This is why two 100 kW quotes on paper can differ by 20% even when the panel and inverter kit is identical — the full commercial solar installation cost always depends on the specific building, not just the kilowatts.
How much roof area does commercial solar need?
Modern commercial modules (typically 440–590 W each) need roughly 6 to 7 m² of roof per kW once you include walkways, inter-row spacing on flat roofs, and set-backs from the roof edge. So a 100 kW system realistically wants 600–700 m² of usable roof — not the whole building footprint, but the clear, unshaded, structurally sound portion of it.
| System size | Roof area needed (usable) | Rough building type |
|---|---|---|
| 30 kW | ~180–210 m² | Small office / retail unit |
| 50 kW | ~300–350 m² | SME office or workshop |
| 100 kW | ~600–700 m² | Light-industrial unit |
| 250 kW | ~1,500–1,750 m² | Mid-size warehouse |
| 500 kW | ~3,000–3,500 m² | Large distribution shed |
| 1 MW | ~6,000–7,000 m² | Major logistics / manufacturing roof |
Pitched south-facing roofs pack in tighter (nearer 6 m²/kW) because panels sit flush; flat roofs on ballasted or east-west frames need the wider 7 m²/kW to avoid rows shading each other. If your roof is smaller than the figure above, you are capacity-limited by area rather than budget, and the per-kW economics shift slightly because fixed costs spread across fewer kilowatts.
What is the cost per square metre of commercial solar?
Dividing installed cost by roof area gives a per-m² figure that is useful when you are thinking in terms of “how much of my roof, and what will covering it cost”. In 2026 the answer is roughly £110 to £160 per square metre of roof actually covered with panels.
| Metric | Lower end (large system) | Upper end (small system) |
|---|---|---|
| Cost per kW | ~£750 / kW | ~£1,050 / kW |
| Roof area per kW | ~7 m² / kW | ~6 m² / kW |
| Cost per m² of roof | ~£110 / m² | ~£160 / m² |
Read it as a bracket, not a precise unit rate: a big 1 MW roof lands near £110/m² because both the per-kW price and the packing density work in your favour, while a small 30 kW roof sits closer to £160/m². This per-m² lens is handy for landlords and multi-let estates comparing several roofs of different sizes on one benchmark. For the underlying component pricing behind these figures, see our solar panel costs reference.
What moves the £/kW up or down?
The same kilowatt of solar can cost £750 or £1,050 depending on five main variables:
- Scale. The biggest lever. Every doubling of system size shaves roughly £50–£80/kW off the price as fixed costs amortise. This is why the jump from 30 kW to 100 kW saves more per kW than the jump from 500 kW to 1 MW.
- Roof type and access. Flat, single-pitch, structurally sound industrial roofs are cheapest. Fragile roofs, asbestos-cement sheeting (pre-2000), steep pitches, or no anchor points add survey and scaffold cost. An asbestos R&D survey alone is £400–£900.
- DNO reinforcement. A G98 connection (sub-100 kW effectively, ≤3.68 kW per phase notification) is cheap and fast. A G99 application above that threshold can be free or can carry a five-figure reinforcement charge if the local network is constrained — always ask whether the DNO fee is included or pass-through.
- Three-phase vs single-phase supply. Most commercial sites are three-phase, which suits commercial string inverters well. A site that needs a supply upgrade to accept the export adds cost and lead time.
- Kit specification. Module-level optimisers, premium monitoring portals, or Tier 1 flagship panels push the panel and inverter lines up. A mainstream Tier 1 module with a leading three-phase string inverter is the value sweet spot.
Worked example: a 100 kW light-industrial roof
A 100 kW system at roughly £900/kW is £90,000 ex VAT, covers about 650 m² of roof, and generates around 90,000–95,000 kWh per year in typical UK irradiance (roughly 900–1,150 kWh per kWp depending on region and orientation). At a 2026 commercial import rate near 26p/kWh with 65% self-consumption, that is in the region of £16,000–£17,000 of Year 1 benefit before tax relief.
Then the Annual Investment Allowance does the heavy lifting: solar qualifies for 100% first-year capital allowances, so a profitable company paying corporation tax at 25% cuts its effective net cost by about a quarter — turning £90,000 into roughly £67,500 net. That typically pulls simple payback from around five-and-a-half years down towards four. To model this against your own consumption and tariff, use the commercial solar savings calculator uk.
Frequently asked questions
Is commercial solar cheaper per kW than residential? Yes, substantially. Commercial systems benefit from scale, simpler flat or single-pitch roofs, and three-phase inverters, so £/kW is typically 30–50% below a domestic install of the same nominal size.
Why is the per-kW price lower on bigger systems? Fixed costs — design, DNO paperwork, scaffold mobilisation, commissioning, project management — stay broadly the same whether the array is 100 kW or 1 MW, so they spread across more capacity. Hence £1,050/kW at 30 kW versus £750/kW at 1 MW.
How many square metres do I need per kW? Around 6–7 m² of usable roof per kW: about 6 m²/kW on tight pitched roofs and nearer 7 m²/kW on flat roofs using east-west or ballasted frames. So 100 kW needs roughly 600–700 m².
What is the cost per square metre? Roughly £110–£160 per m² of roof actually covered with panels in 2026, landing near the lower end on large systems and the upper end on small ones.
Does the £/kW include the grid connection? Not always. A straightforward G98 or G99 connection may be included, but network reinforcement charges are frequently quoted as pass-through. Confirm whether the DNO cost is inside the headline figure before comparing quotes.
Normalise the quote, then decide
When you compare commercial solar quotes, convert every one to £/kW and £/m² first — it exposes the outliers instantly and tells you whether a “cheap” quote has simply left the DNO fee, scaffold or asbestos survey out of the headline. A defensible 2026 quote sits inside the £750–£1,050/kW band, itemises panels, inverter, mounting, electrical/DNO and install separately, and states clearly whether the grid connection is included.
Once you have a size and a roof area in mind, get a tailored quote and we will model it on your real half-hourly consumption rather than a bill estimate — that is the only way to turn a per-kW benchmark into a firm payback figure for your building.