Commercial solar has moved from “nice-to-have sustainability project” to one of the more predictable capital investments a UK business can make. But the pricing conversation is different from domestic solar in almost every respect — the £/kWp falls sharply as systems scale, the tax treatment changes the real payback, and the finance options (cash, loan, PPA, asset finance) each shift the numbers again. This piece sets out what commercial solar actually costs per kW in the UK in 2026, with worked examples at 30kWp, 50kWp, 100kWp and 250kWp, and what capital allowances do to the maths.
Why commercial £/kWp is not the same conversation as domestic
Domestic solar pricing is dominated by fixed costs — scaffolding, a single day’s labour, one inverter, one consumer unit upgrade — so a 3kW system and a 6kW system don’t cost twice as much per kW. Commercial rooftop and ground-mount projects behave the same way but the curve is steeper, because the fixed-cost components (design, structural survey, DNO application, mobilisation, scaffold/access equipment, commissioning) are spread across a much larger array, and because commercial buyers get trade pricing on panels, inverters and mounting rail that a domestic installer passes on less of.
As a rough planning figure for 2026, expect commercial-scale solar to land somewhere in the £900–£1,200 per kWp installed range, with the lower end reserved for larger, simpler flat-roof or ground-mount projects and the upper end for smaller commercial jobs, complex roof types (slate, asbestos-cement, multiple roof planes), or sites needing significant electrical infrastructure work. That range is consistent with what independent buyers report to us across the network’s commercial-facing sites, and it should be treated as a planning band rather than a quote — every roof, DNO connection and structural survey changes the number.
Worked examples: 30kWp to 250kWp
The table below uses the £900–£1,200/kWp band applied to typical system sizes, plus rough annual generation using the UK’s typical commercial yield of roughly 850 kWh per kWp per year (rising toward 950–1,050 kWh/kWp in the sunniest parts of the south, lower in Scotland and the north).
| System size | Installed cost range | Typical annual generation | Roof/ground footprint (approx) |
|---|---|---|---|
| 30 kWp | £27,000 – £36,000 | ~25,500 kWh | ~150–180 m² |
| 50 kWp | £45,000 – £60,000 | ~42,500 kWh | ~250–300 m² |
| 100 kWp | £90,000 – £120,000 | ~85,000 kWh | ~500–600 m² |
| 250 kWp | £200,000 – £270,000* | ~212,500 kWh | ~1,250–1,500 m² |
*250kWp systems increasingly fall below £900/kWp on simple large-roof or ground-mount sites because fixed costs are a smaller share of the total — but they can also trip into three-phase grid reinforcement or DNO capacity constraints that add cost, so treat this as the widest range of the four.
A few things move these numbers in practice. Ground-mount arrays need groundworks and fencing that flat-roof arrays don’t. A roof already near its structural load limit needs a survey and possibly reinforcement. And any system above roughly 50kWp is likely to need a formal DNO (District Network Operator) application before connection — sometimes straightforward, sometimes requiring grid reinforcement that adds real cost and months of lead time. Get the DNO question answered early; it’s the single biggest cause of commercial solar projects overrunning on both cost and timeline.
For businesses wanting a second opinion on where their own quote sits, commercialsolarpanelsinstallation.co.uk is a useful commercial-installation hub for cross-checking scope against price, and our own commercial solar panel costs page breaks the same £/kWp banding down by building type.
What actually drives the price per kW
Roof type and condition. Flat industrial roofs (the classic warehouse or factory shed) are usually the cheapest per kWp to fit because mounting is a ballasted or lightly-fixed system with no penetrations, and large open roof areas mean fewer edge-of-array losses. Pitched or complex roofs — schools, hotels, older commercial premises — cost more per kWp because of scaffolding, multiple array orientations and bespoke racking. If you’re assessing a factory or distribution shed specifically, solarpanelsforfactories.co.uk and solarpanelsforwarehouses.co.uk both cover the roof-type cost differences in more depth than a generic commercial page will.
Inverter architecture. Commercial systems typically use one or more string inverters or a central inverter rather than domestic-style micro-inverters or optimisers on every panel — this is part of why £/kWp falls with scale. String inverters generally last 10–15 years and cost roughly £500–£1,000 each to replace domestically; commercial string and central inverters cost proportionally more but represent a smaller share of total project cost as the array grows.
Grid connection and DNO capacity. As above — this is the wildcard. A site with existing three-phase supply and spare DNO capacity is straightforward. A site that needs a supply upgrade can see tens of thousands added before a single panel goes up.
Panel technology. 2026 commercial installs are increasingly specifying N-type TOPCon or heterojunction (HJT) panels over older P-type PERC, because the degradation rate is lower (roughly 0.4%/year against older panels’ closer to 0.5–0.7%/year) and the 25–30+ year usable life better matches a business’s longer investment horizon. The premium for N-type has narrowed significantly and, on commercial-scale orders, is often a marginal cost difference rather than a material one.
Sector-specific requirements. Hospitals and care homes often need enhanced resilience and backup provision; hotels and restaurants may want battery integration to manage peak demand charges; schools and colleges typically want the simplest, lowest-maintenance system given in-house facilities capacity. If you’re specifying for one of these sectors, the sector-specific hubs — solarpanelsforhospitals.co.uk, solarpanelsforcarehomes.co.uk, solarpanelsforhotels.co.uk, solarpanelsforrestaurants.co.uk, solarpanelsforschools.co.uk and solarpanelsforcolleges.co.uk — go into the load-profile and use-case detail that a generic commercial quote won’t.
Capital allowances: the number that changes the real payback
This is where commercial solar pricing genuinely diverges from domestic, and where a lot of businesses under-value their own project. Domestic solar in Great Britain currently sits at 0% VAT until 31 March 2027 (scheduled to revert to 5% after that), which is a straightforward saving. Commercial buyers don’t get the VAT relief in the same way, but they get access to capital allowances that domestic buyers can’t use at all.
Solar PV plant and machinery can qualify for the Annual Investment Allowance (AIA), which currently allows businesses to deduct the full qualifying cost of plant and machinery from taxable profit in the year of purchase, up to the AIA cap (currently £1 million). For a company paying corporation tax at 25%, that means a £100,000 solar installation can reduce the tax bill by roughly £25,000 in the year of investment — effectively cutting the net cost of the system by a quarter, assuming sufficient taxable profit to offset. This is separate from, and should not be confused with, the Boiler Upgrade Scheme (which funds heat pumps, not solar) or the various farm-specific schemes — solar PV’s capital allowance treatment sits under general plant and machinery rules, not a bespoke solar grant.
Businesses considering how AIA interacts with leasing, hire purchase or a Power Purchase Agreement (PPA) — where a third party owns the system and you buy the electricity — should work through the specifics with an accountant, because ownership structure determines who can claim the allowance. commercialsolarfinance.co.uk and solarassetfinance.co.uk both cover the finance-structure trade-offs (cash purchase vs loan vs asset finance vs PPA) in more depth, and solarpowerpurchaseagreements.co.uk is worth reading before ruling PPAs in or out — a zero-capex PPA changes the entire £/kWp conversation because you’re not the one buying the kWp at all.
Businesses should also check solarpanelgrantsforbusinesses.co.uk for the current state of sector and nation-specific support — farm-based commercial solar in England, for instance, sits under the Improving Farm Productivity grant at roughly 25% of eligible cost (not the 40% figure sometimes quoted, which doesn’t apply here), and devolved administrations run separate schemes with different rates, so it’s worth checking what actually applies to your postcode and sector rather than assuming a blanket UK-wide rate.
Payback: what the numbers actually look like
Ignoring capital allowances for a moment, a straightforward payback calculation for a 100kWp system:
- Installed cost: ~£90,000–£120,000
- Annual generation: ~85,000 kWh
- If the business consumes most of that on-site at, say, 25p/kWh avoided import cost: ~£21,250/year in avoided electricity spend
- Simple payback before allowances: roughly 4.5–5.5 years
Factor in the AIA saving (roughly £22,500–£30,000 off the net cost for a 25%-taxpayer company with sufficient profit) and the effective payback can compress to somewhere in the 3.5–4.5 year range — before accounting for electricity price inflation, which has historically only strengthened the case. Export income via the Smart Export Guarantee adds a further, smaller contribution for any surplus generation, though SEG rates are supplier-set and vary — typically in a roughly 12–20p/kWh band at the better end — rather than a fixed national tariff, so it shouldn’t be the basis of your core payback case; treat it as upside.
Battery storage changes this picture again. Commercial battery storage (from providers such as those covered at batterystorageforbusiness.co.uk) lets a business shift self-consumption to cover evening or weekend demand and can also participate in demand-charge reduction, though it adds capital cost on top of the solar array itself and needs its own payback calculation rather than being assumed as “free” upside.
Getting quotes that are actually comparable
Because commercial £/kWp varies so much with roof type, DNO capacity and finance structure, the single most useful thing a business can do before comparing quotes is insist every installer prices against the same specification — same panel tier, same inverter architecture, same scope of electrical works, same assumptions on scaffolding/access. A £900/kWp quote that excludes DNO application costs and a £1,150/kWp quote that includes them are not actually being compared on a like-for-like basis.
For businesses in the East Anglia/Essex region specifically, ececoenergy.com handles commercial solar and battery installs and can price against a real roof rather than a generic band; in Bristol and the wider South West, drenergyltd.co.uk covers commercial-scale projects with the same specification discipline. Both are worth a conversation even if you end up going elsewhere, simply to establish what a properly-scoped quote for your building type should include.
If you’re earlier in the process and still weighing whether solar, a PPA, or asset finance is the right structure for your business before you get quotes at all, our solar panel payback period guide and solar panel calculator are a reasonable starting point, and solarweekly.co.uk tracks the wider 2026 UK installation and pricing trend if you want the market context behind these figures.
The bottom line
Commercial solar at UK 2026 prices sits roughly in a £900–£1,200/kWp band, falling toward the lower end as systems scale past 100kWp on simple roofs, and rising when DNO connection, structural work or complex roof geometry are involved. Capital allowances — specifically the Annual Investment Allowance — are the factor most businesses underweight when they first look at the numbers, and can meaningfully compress payback from the 4.5–5.5 year range down toward 3.5–4.5 years for a standard-rate taxpayer with sufficient profit to offset. Get quotes scoped identically, ask explicitly about DNO capacity before signing anything, and treat the SEG export income as upside rather than the basis of your case.