Key facts
10kW starter systemOften suitable for shops, clinics, small offices and workshops with modest daytime use.
30-50kW systemsCommon for SMEs with stronger daytime demand and enough roof space.
100kW+Usually needs more detailed roof, grid, insurance and finance checks.
FundingCosts may be reduced through local grants, tax allowances, SEG export payments or sector funding where eligible.
Best next stepGather usage data, roof details and lease/ownership evidence before requesting installer quotes.
Indicative commercial solar budgets
These are planning ranges for early budgeting. Installed cost can move materially if the roof needs remedial work, specialist access, long cable runs, export protection, metering upgrades or battery storage.
| System size | Typical site | Planning budget | Useful checks |
|---|---|---|---|
| 10kW | Small office, shop, workshop | GBP 10,000-16,000 | Daytime load, roof access, inverter location |
| 30kW | SME unit, retail, leisure, small warehouse | GBP 25,000-45,000 | DNO position, self-consumption, grant match funding |
| 50kW | Warehouse, factory, school-size roof | GBP 40,000-70,000 | Structural survey, export limit, insurance, metering |
| 100kW+ | Larger industrial or logistics site | GBP 75,000-120,000+ | Grid application, phased install, project finance |
What changes payback fastest?
- Daytime usage: self-consuming solar power is usually more valuable than exporting it.
- Import tariff: higher electricity prices usually improve the saving from every generated kWh used on site.
- Export route: SEG can help, but it should not be the only reason the project works.
- Battery fit: batteries can help peak shaving and evening use, but they add cost and need load modelling.
- Tax position: solar panels are special-rate plant, so the post-tax case needs accountant review.
Sources checked
- GOV.UK - Find government grants
- GOV.UK - business green funding
- Ofgem - Smart Export Guarantee
- GOV.UK - VAT Notice 708/6
- HMRC - solar panels capital allowances
- GOV.UK - full expensing and first-year allowances
- GOV.UK - green business rates measures
- GOV.UK - Rural England Prosperity Fund example
- Salix - Public Sector Decarbonisation Scheme
- GOV.UK - Public Sector Low Carbon Skills Fund
- Planning Data - non-domestic solar permitted development
Great British Energy is an independent guide and is not affiliated with the government-owned Great British Energy at gbe.gov.uk. Funding rules change; verify against official sources before committing spend.