500kW Solar System Cost UK — 2026 Guide
A 500kW commercial solar system costs £325,000 to £400,000 fully installed in 2026 — £650–£800 per kWp, the best per-unit pricing on the rooftop curve. Projects at this scale succeed or fail on grid engineering and procurement discipline, not panel choice.
What half a megawatt costs in 2026
At 500kW, hardware buying power and installation efficiency push the per-kWp rate to its floor for rooftop work. But the project also crosses thresholds that introduce real engineering cost: principal contractor duties under CDM, lifting plans for inverter and switchgear positions, and a G99 study that may touch the 11kV network.
| Cost line | Typical 2026 range |
|---|---|
| Panels (~1,090 × 460W, tier-1) | £88,000–£110,000 |
| Inverters, switchgear, AC protection | £26,000–£36,000 |
| Mounting system | £30,000–£40,000 |
| Electrical installation and integration | £70,000–£95,000 |
| Access, lifting, edge protection, site setup | £22,000–£32,000 |
| Design, G99 study and witnessing, structural engineering, CDM | £15,000–£22,000 |
| Monitoring, metering, O&M mobilisation | £5,000–£8,000 |
Items deliberately excluded from the table because they are site-specific: DNO reinforcement (zero on a well-connected site, £100,000+ on a weak one), roof remediation, and HV works where a new transformer connection is required. These are exactly the items a desk feasibility plus early DNO application is designed to surface before you commit.
The three questions that decide a 500kW project
1. What does the DNO say? Export of 500kW will trigger a proper network study. Well-connected urban industrial sites often sail through; rural sites on saturated feeders may face export caps or reinforcement bills. Apply early — the application fee is trivial against the information value.
2. Can the roof carry it? Total distributed load is in the region of 25–30 tonnes. Most modern big-shed structures designed to current codes accommodate this; 1970s–80s portal frames need genuine structural assessment, and occasionally a reduced layout. A £3,000 structural study is cheap insurance on a £360,000 asset.
3. Who owns the asset? At this scale every funding route is available: cash purchase with AIA or 50% first-year allowance, asset finance, or a roof-lease PPA where a funder owns the system. Ownership maximises return; PPA maximises simplicity. The wrong answer is defaulting to one without modelling both.
Worked example: 3PL distribution centre, M62 corridor
A third-party logistics operator installs 500kW on a 12,000 m² shed at £352,000, after a G99 response permitting 350kW export with limitation. Yield: 448,000 kWh. Racking, conveyors, charging and chilled storage drive 82% self-consumption — £91,800 a year at 25p/kWh — plus £5,200 export within the cap. Year-one tax relief on the full cost returns ~£88,000. Net cost ~£264,000, simple payback 2.7 years, and the building's EPC position improves ahead of tightening MEES requirements — which now influence institutional landlords' willingness to renew big-shed leases.
Procurement discipline pays for itself
At 500kW a 5p/Wp pricing difference is £25,000, so run a proper tender: identical scope document to three installers, PVSyst files required, exclusions listed line by line, and the DNO position stated in every bid. Our price factors guide doubles as a scope checklist. For context on how this size compares across building types, see cost by sector — and if your load is closer to half this size, the 250kW guide is the better read.
500kW solar system — common questions
How many panels and how much roof does 500kW take?
Roughly 1,090 panels at 460W across 2,200–2,500 square metres of usable roof. Buildings that fit the profile are large distribution centres, major manufacturing plants and multi-bay industrial estates — typically a footprint of 5,000 square metres or more.
Will a 500kW system connect at low voltage or high voltage?
It depends on your existing supply. Sites already on an HV (11kV) supply with their own transformer usually integrate solar on the LV side of their own substation, which keeps costs contained. Sites on large LV supplies may be told by the DNO that 500kW of export requires an HV connection or significant reinforcement — a cost swing measured in tens of thousands, settled only by the formal G99 study.
What does a 500kW array generate and save?
Expect 425,000–475,000 kWh per year. An operation self-consuming 85% at 25p/kWh saves roughly £95,000 a year, with export adding £4,000–£8,000 depending on the offtake arrangement. At a £360,000 install cost that is sub-4-year payback before tax relief — and around 3 years after it.
Why are we being offered a PPA instead of a purchase at this size?
Because at 500kW the economics support third-party ownership: a funder builds and owns the system on your roof and sells you the power at a discounted rate over 15–25 years. It removes capex and maintenance risk but captures less of the value for you. If your balance sheet can carry the asset, ownership virtually always wins on whole-life numbers — see our finance vs purchase comparison.