How much does commercial solar cost in 2026?
A working-numbers guide for 50kWp to 1MW commercial solar PV in the UK. We strip out the marketing pricing and show what you should actually plan for — capex, soft costs, ongoing operating expense, and the after-tax position once allowances apply.
£700–£1,000/kWp on systems >100kWp
£900–£1,200/kWp on systems <50kWp
17–19% lifetime allowance value vs cost
The five layers of commercial solar cost
Most quotes treat commercial solar as a single line: kWp × £/kWp = price. That hides where the money actually goes, where the negotiation room is, and where the hidden costs accumulate. The cleanest way to budget a project is to break the cost into five separate layers, each with its own price-discovery approach.
Modules, inverters, mounting, cabling
Roughly 45–55% of total turnkey cost. The competitive market has compressed module pricing toward £0.18/Wp for tier-1 mono-PERC and £0.20–£0.22/Wp for TopCon, with inverters at £0.08–£0.12/Wp depending on string vs central architecture. Mounting and cabling adds another £0.15–£0.25/Wp. Bill of materials transparency is the single biggest negotiation lever — insist on a line-item BOM, not a system price.
Site labour, mechanical and electrical
15–20% of turnkey. Heavily roof-condition dependent. New industrial buildings with standing-seam roofs and rooftop access points run 20–25% lower than retrofit installs on aged metal-deck roofs requiring scaffold and edge protection. Multi-roof estates also bear additional mobilisation cost. The best installer estimates break out site days, crew size, and access strategy explicitly.
Design, structural survey, DNO, planning
8–12% of turnkey. This is where price-discovery is hardest and where cost can spike. DNO connection above 200kW often triggers reinforcement and AVR studies; specific sites may face tens of thousands of pounds in network reinforcement. Structural surveys for older roofs run £3k–£8k. Planning is required only on specific listed or sensitive sites but adds £4k–£10k where needed. We always isolate these as a discrete budget line so the headline £/kWp is comparable across quotes.
Testing, certification, monitoring setup
3–5% of turnkey. G99 commissioning, handover documentation, monitoring portal configuration, MCS certification (where applicable for SEG eligibility). Worth scrutinising: who holds responsibility if commissioning is delayed because a DNO inspection slot slips, and what triggers final-payment release. Specific milestone-tied payment terms protect against months of post-install limbo.
Monitoring, O&M, inverter replacement reserve
£8–£12 per kWp per year for monitoring and routine maintenance. Inverter replacement is the largest single ongoing cost — £80–£120/kWp at roughly year 12, or 11–13% of original capex. Strong projects budget this in the 25-year IRR up front; weak projects ignore it and surprise themselves at year 11 when the warranty horizon expires and string inverters start failing.
Worked example: 250kWp on a £200,000 commercial system
£105,000 (52.5%) — modules £55k, inverters £25k, mounting and cabling £25k.
£37,000 (18.5%) — site days, scaffolding, M&E.
£20,000 (10%) — DNO, structural, design, planning.
£8,000 (4%) — G99, certification, handover.
£30,000 (15%) — installer margin and 5% project contingency.
£175,000 year one (after £25k FYA), trending to £163,000 once special-rate pool relief is claimed over the holding period.
Where the cost goes versus where the value is
A useful framing: roughly 70% of project cost is hardware-and-labour commodity, 15% is soft-cost project management that's worth paying full price for (good DNO work and a real structural survey save tens of thousands later), and 15% is installer margin and contingency that's where price negotiation lives. Pushing too hard on the 70% by switching to lower-tier hardware reduces lifetime energy yield by more than the saving. Pushing too hard on the 15% by removing contingency leaves you exposed to the first DNO surprise. The right negotiation focuses on installer margin transparency — that's where price discovery actually moves the needle.
Cost benchmarks by sector and project size
| Project profile | System size | Typical capex | £/kWp range |
|---|---|---|---|
| SME industrial unit | 30–80 kWp | £28k–£80k | £950–£1,150 |
| Mid-tier manufacturing | 100–300 kWp | £85k–£260k | £800–£950 |
| Logistics warehouse | 300–800 kWp | £230k–£640k | £750–£900 |
| Industrial estate / portfolio | 800kWp–2MWp | £600k–£1.6m | £700–£850 |
| Public sector PSDS bundle | 200kWp–1.5MWp | £170k–£1.3m | £800–£950 |
| Agricultural ground-mount | 100kWp–1MWp | £70k–£800k | £700–£850 |
Size-specific cost guides
Each system size has different cost-breakdown ratios, FYA capture mechanics, and best-fit profiles. Detailed guides:
100 kWp cost guide
£85k–£110k · £850–£1,100/kWp
200 kWp cost guide
£160k–£200k · £800–£1,000/kWp
500 kWp cost guide
£360k–£450k · £720–£900/kWp
1 MWp cost guide
£720k–£950k · £700–£900/kWp
Run your own numbers in the interactive calculator →
Cost FAQs
What does a 250kWp commercial solar system cost in 2026?
How much should I budget per kWp?
What are the hidden cost lines that catch buyers out?
How does the 50% FYA change the effective cost?
Can we lock in pricing now and install in 12 months?
Get a comparable cost benchmark for your specific site
Send postcode, roof area, and annual electricity consumption. We return an indicative capex range plus the after-tax model across all six finance structures.
Request a finance review£/kWp installed by system size
Indicative installed costs from 2026 UK commercial projects we've advised on. Actual quotes vary ±15% depending on roof complexity, DNO position, and battery integration.
Costs include modules, inverters, mounting, AC infrastructure, DNO connection, commissioning. Battery storage adds typically £350-450/kWh on top.