25 kWp commercial solar PV cost in the UK (2026)
At 2026 prices, a 25 kWp commercial solar PV system costs £22,000 - £29,500 installed (excl. VAT). Typical post-tax payback: 3.4-4.1 years.
25 kWp cost summary
| System size | 25 kWp |
| Installed cost (2026, excl. VAT) | £22,000 - £29,500 |
| £/Wp | £0.88 - £1.18 |
| Number of panels (450W) | ~55 |
| Roof area required | ~140 m² |
| Annual generation (UK avg) | 23,750 kWh |
| Best fit for | small office, café, restaurant, retail unit |
| Best grant stack | AIA / Full Expensing + SEG + regional grant £1k-£5k |
Year-1 maths breakdown
| Gross capex (mid) | £25,750 |
| 100% Full Expensing tax saving (25% CT) | -£6,438 |
| Net effective cost | £19,312 |
| Annual self-consumption (68%) | 16,150 kWh saving £4,522/year |
| Annual SEG export (32%) | 7,600 kWh earning £228 - £1,140/year |
| Total year-1 savings/revenue | £4,750 - £5,662 |
| Post-tax payback | 3.4 - 4.1 years |
25 kWp commercial solar · FAQs
How much does a 25 kWp commercial solar system cost in 2026?
At 2026 prices, a 25 kWp commercial solar PV system costs approximately £22,000 - £29,500 installed (excl. VAT). After 100% Full Expensing tax relief for a limited company at the 25% main CT rate, net cost is around £16,500 - £22,125.
What is the payback period for a 25 kWp commercial solar system?
With 68% self-consumption and SEG export tariffs of 3p-15p/kWh, a 25 kWp system typically pays back in 3.4-4.1 years post-tax.
What size roof is needed for a 25 kWp system?
A 25 kWp system requires approximately 140 m² of unshaded roof area — around 55 450W panels.
How much electricity will a 25 kWp system generate?
A 25 kWp system generates approximately 23,750 kWh per year in UK conditions. Best fit for small office, café, restaurant, retail unit.
Which grants apply to a 25 kWp system?
Best grant fit: AIA / Full Expensing + SEG + regional grant £1k-£5k. Always use the eligibility calculator for a personalised match.
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