Cost & ROI by system size
What commercial solar costs, by system size
See real UK installed-cost ranges, typical payback and building fit at 100kW, 250kW, 500kW and 1MW+. Moreover, this guide includes the capital-allowances detail most guides get wrong. Every figure links to a source you can check yourself.
100kW Commercial Solar
The typical entry point for a serious commercial system.
Installed cost, payback and building fit for a 100kWp commercial solar system — the size where economies of scale start to bite and MCS's small-scale standard no longer applies.
- Typical cost
- £80,000–£100,000 installed (approx. £800–£1,000 per kWp, ex-VAT)
- Typical payback
- 5–7 years before finance costs, shorter once capital allowances are applied
250kW Commercial Solar
The sweet spot for larger warehouses, distribution units and business parks.
Installed cost, payback and building fit for a 250kWp commercial solar system — where grid-connection headroom starts to matter and per-kWp pricing improves further.
- Typical cost
- £175,000–£215,000 installed (approx. £700–£850 per kWp, ex-VAT)
- Typical payback
- 4.5–6.5 years before finance costs, shorter once capital allowances are applied
500kW Commercial Solar
Large-roof industrial and logistics buildings, where the economics are strongest.
Installed cost, payback and building fit for a 500kWp commercial solar system — large-roof industrial and logistics territory, and where capital allowances need careful modelling.
- Typical cost
- £300,000–£375,000 installed (approx. £600–£750 per kWp, ex-VAT)
- Typical payback
- 4–6 years before finance costs, shorter once capital allowances are applied
1MW+ Commercial Solar
Major logistics, manufacturing and multi-building estates.
Installed cost, payback and building fit for a 1MW+ commercial solar system — where grid connection becomes the critical path and portfolio thinking starts to pay off.
- Typical cost
- £600,000–£720,000+ installed for 1MWp (approx. £600–£720 per kWp, ex-VAT), falling further at larger scale
- Typical payback
- 4–6.5 years before finance costs; more sensitive to export share and grid terms than smaller bands
Not sure which band fits your site?
Most of these figures shift with roof condition, grid capacity, your tariffs and your load profile. As a result, no single range fits every building. A feasibility study or ROI model gives you numbers for your actual site instead.