30kW Solar System Cost UK — 2026 Guide
A 30kW commercial solar system costs £27,000 to £33,000 fully installed in 2026 — that is £900–£1,100 per kWp, the top of the commercial pricing curve because fixed project costs are spread over relatively few panels.
Where the money goes on a 30kW install
At this size, hardware is well under half the bill. The panels themselves — around 66 units at 2026 trade prices — account for roughly £6,500–£8,500. The remainder is the work of getting them safely and legally onto a commercial roof.
| Cost line | Typical 2026 range | Share |
|---|---|---|
| Panels (~66 × 450W, tier-1) | £6,500–£8,500 | ~25% |
| Inverter(s) and protection | £2,500–£4,000 | ~11% |
| Mounting and roof interface | £2,500–£3,500 | ~10% |
| Electrical labour and cabling | £6,000–£8,000 | ~24% |
| Scaffolding / access | £2,500–£4,500 | ~12% |
| Design, G99, structural sign-off, commissioning | £3,000–£4,500 | ~13% |
| Monitoring, metering, handover pack | £1,000–£1,500 | ~5% |
Notice what that table implies: the panels could be free and a 30kW project would still cost over £20,000. This is why "panel prices have crashed" headlines have not crashed installed prices — labour, scaffolding and compliance costs are stable or rising. It is also why per-kWp pricing improves so sharply at 100kW and above, where the same scaffold, design fee and DNO application serve three times the capacity.
What a 30kW system suits
This is the classic size for a small industrial unit, a workshop with three-phase machinery, a medium farm building, a GP surgery, a convenience store with refrigeration, or a small office block. The common thread is an annual electricity bill of roughly £8,000–£18,000 with meaningful daytime consumption. If your bill is well above £20,000 a year, you will almost certainly get better economics from a 50kW system — the marginal cost of the extra 20kW is low once the scaffold is up.
Output and payback: a worked example
Take a joinery business in the Midlands with a 30kW array on a south-east facing steel roof, installed at £29,500. Modelled yield is 26,400 kWh per year. The workshop runs five days a week, so 78% of generation is used on-site, displacing grid power at 26.5p/kWh — worth £5,457 a year. The exported 22% earns about £350 at typical 2026 export rates. Year-one benefit: roughly £5,800, before the corporation tax relief on the capital cost via the Annual Investment Allowance. Simple payback lands just past the five-year mark, with the system warranted for 25 years.
What pushes a 30kW price up or down
- Roof type. Trapezoidal steel is the cheap case. Flat membrane roofs need ballasted or penetrative mounting (+£1,500–£3,000). Fragile or asbestos roofs usually mean netting, crawl boards or refusal.
- Access. A roadside unit with hardstanding for a scissor lift prices better than a courtyard property needing full scaffold wraps.
- Supply. An existing three-phase supply with headroom keeps the G99 simple. Single-phase sites need an upgrade priced separately.
- Electrical condition. Old fuse boards or undersized distribution can add £1,000–£3,000 of remedial work — better discovered at survey than mid-install.
The full list, including the items that affect bigger systems, is in our price factors guide. For how this size compares across building types, see cost by sector.
30kW solar system — common questions
How many panels is a 30kW solar system?
Around 65–68 panels at the 440–460W ratings standard in 2026, occupying roughly 130–150 square metres of unshaded roof. On a typical small industrial unit that is about half of one roof pitch.
Does a 30kW system need a DNO application?
Yes. Anything above 16A per phase (about 11kW on a three-phase supply) needs a G99 application to your district network operator before connection. For 30kW on an existing three-phase supply this is normally routine — budget £300–£1,500 for application and witnessing costs, which a good installer includes in the quoted price.
Can I install 30kW on a single-phase supply?
Realistically no. Single-phase connections are limited to far less inverter capacity, and most DNOs will not approve 30kW on one phase. If your premises only has single-phase power, a supply upgrade is needed first — typically £2,000–£8,000 depending on distance to the nearest three-phase main, and worth pricing before anything else.
What does a 30kW system save per year?
A 30kW array yields roughly 25,500–28,500 kWh per year on a well-oriented UK roof. A business using 80% of that on-site at a 26p/kWh unit rate saves around £5,300–£5,900 a year, plus a small export income on the remainder. Against a £30,000 install that is a 5–6 year simple payback.