How Much Does Commercial Property Solar Cost in 2026?
24 June 2026 · SEO Dons Editorial
Real 2026 UK numbers — £/kWp by system size, total project values, payback, and the tax levers that shorten it — written for property owners and investors.
The honest answer is a range, and the range is wide for a reason: a commercial rooftop array is priced per kilowatt-peak (kWp), and the per-unit rate falls as the system gets bigger. In 2026 most commercial installs land between roughly £700 and £1,100 per kWp before VAT, with the higher end reflecting smaller jobs, awkward roofs, and significant grid or structural work. Commercial solar carries 0% VAT on supply and installation (it has done since April 2022), so the figures below are the figures you pay — there is no tax to add back.
This page is written for the party that owns the asset, not the party that pays the electricity bill. That distinction changes how you should read every number here, because the question for an owner is rarely “what does it cost” in isolation — it is “what does it cost, who benefits, and how fast does the post-tax position turn positive”. We will get to all three.
Price per kWp by system size
Scale is the single biggest lever on unit cost. Fixed costs — design, scaffolding, the G99 grid application, a structural survey — are spread across more panels on a larger roof, so a 500kWp array almost always beats a 50kWp array on £/kWp by a comfortable margin. Use these as planning bands, not quotes; a real number needs a roof, a half-hourly consumption profile and a DNO position.
| System size | Indicative total (ex-VAT) | Rough £/kWp | Typical roof |
|---|---|---|---|
| 50 kWp | £35,000–£60,000 | ~£900–£1,100 | Single retail/office unit |
| 100 kWp | £82,000–£110,000 | ~£820–£1,000 | Mid-size warehouse, larger office |
| 250 kWp | £150,000–£240,000 (≈£185,000 worked) | ~£740–£900 | Distribution shed, retail park unit |
| 500 kWp | £350,000–£500,000 | ~£700–£900 | Large logistics roof |
| 1 MWp | £700,000–£900,000 | ~£700–£800 | Big-box / multi-roof portfolio |
A reasonable working assumption for UK yield is around 950 kWh per kWp per year. So a 250kWp system generates roughly 237,000 kWh annually — the value of which depends almost entirely on what share you use on site versus export.
What actually pays it back: self-consumption
The most important number in any commercial solar appraisal is not the cost — it is the self-consumption rate, the proportion of generation used on site rather than exported. The reason is the spread between the two prices.
Self-consumed solar displaces grid electricity at roughly 24–28p/kWh in 2026 (large and medium commercial rates sit at 24.3p and 26.1p ex VAT and CCL; micro and small users pay more, up to 31.4p). Exported solar earns the Smart Export Guarantee (SEG) — a supplier-set rate, typically 12–16p/kWh, occasionally higher on conditional tariffs. So every unit you consume on site is worth roughly twice every unit you export.
That is why self-consumption drives the whole model:
- 30–50% — typical for a solar-only system with a daytime-light load
- 50–70% — a single business that shifts operations into daylight hours
- 60–80% — solar plus a battery
- 90–95% — a genuine 24/7 operation (cold storage, data, continuous manufacturing)
An owner-occupier capturing 70% self-consumption is on entirely different economics to a landlord exporting most of the output. This is the split-incentive problem in numbers, and it is why how you structure ownership matters as much as what you spend — covered in the split incentive guide.
Payback — and the tax stack that shortens it
Headline payback for commercial rooftop solar in 2026 runs 4 to 8 years, tightening to 3 to 5 years for high-load sites with strong daytime self-consumption. Those are pre-tax, pre-incentive numbers. Two levers compress them further.
Annual Investment Allowance (AIA). Solar PV is a special rate asset (it counts as an integral feature of the building). The route to 100% first-year tax relief is the AIA, which is permanent at £1m per year — not “full expensing”, which only gives the 50% First-Year Allowance on solar and is restricted to companies and excludes assets bought to lease. For a £185,000 system, AIA can relieve the full capital cost against profits in year one, worth ~£46,000 at the 25% main rate of corporation tax. Where AIA is not available — a landlord leasing the roof, a PPA or roof-lease structure — relief falls back to the 6% writing-down allowance, which is far slower and changes the maths. The detail, and the s.198 fixtures election that matters on any later sale, is in the capital allowances guide for owners.
Business rates exemption. Rooftop solar and co-located storage are 100% exempt from business rates until 31 March 2035 in England. On a 250kW array that is roughly £3,000–£8,000 a year that never appears on the bill. Under a full repairing and insuring lease the occupier is usually the rates payer, so this benefit lands on whoever bears the rates — worth confirming before you assume it accrues to you.
Stack AIA and the rates exemption on a high-self-consumption site and a 6-year gross payback can fall toward 4 years post-tax. The capital is recovered; the asset then generates for another 20-plus years.
The costs that surprise people
The £/kWp bands above cover a clean install on a sound roof with available grid capacity. The overruns come from the things a quick quote leaves out — budget for them up front.
- G99 grid application. Any system above roughly 50kW needs a G99 connection agreement from the Distribution Network Operator. This is the genuine bottleneck on larger schemes: capacity may be constrained, the DNO can require reinforcement works, and timelines run to months. Get the DNO position before you commit to a size.
- Structural survey. Panels and ballast add load. An older roof may need a structural engineer’s sign-off, and occasionally strengthening, before anything is fitted.
- Re-roof or roof condition. Putting a 25-year asset on a roof with 8 years left is a false economy — you pay twice to remove and refit. If the roof is near end-of-life, fold the re-roof into the project and the capital allowance position.
- Scaffolding and access. Height, fragile roofs and restricted access can move scaffolding from a line item into a material cost.
- Planning. The 1MW rooftop cap was removed in December 2023, and most rooftop solar is now permitted development under Class J — but that still carries a 56-day prior approval on design and glint-glare. Listed and scheduled buildings are excluded, and an Article 4 direction can withdraw permitted rights. Not a free pass.
None of these are reasons not to proceed. They are reasons to price the whole project, not just the panels — a £185,000 array with a £30,000 grid reinforcement and a £20,000 re-roof is a £235,000 decision, and pretending otherwise just defers the bad news.
Getting to a real number
The bands here will get you to a board paper. They will not get you to a signed contract, because the two variables that swing the return most — your true self-consumption rate and your DNO grid position — are specific to your roof and your meter. A proper appraisal models generation against your half-hourly profile, sets the right self-consumption assumption, applies the AIA and rates positions to your ownership structure, and prices the hidden costs honestly.
If you want that number for a specific building or portfolio, request a quote with the property address and a recent electricity bill, or read the fuller breakdown on the cost page. We will tell you what it costs, who benefits under your lease, and how fast it turns post-tax positive — and if the answer is “not yet”, we will tell you that too.