How long do commercial solar panels take to pay back?
In 2026, UK commercial solar panels typically pay back in 4-7 years, falling to around 3.5-6 years for limited companies claiming Full Expensing. The payback period depends mainly on how much of the generation is used on site, the current import tariff, and the installed cost per kWp. Systems then keep generating for 25 years or more.
Last updated 30 September 2026.
Key facts at a glance
| Typical payback (2026) | 4-7 years |
|---|---|
| After Full Expensing | Around 3.5-6 years for limited companies |
| Asset life | 25+ years of generation after payback |
| Biggest lever | On-site self-consumption share |
| Installed cost | Indicatively £650-£1,100 per kWp |
| Typical UK yield | 850-1,000 kWh per kWp per year |
What decides the payback period
Payback is the installed cost divided by the annual saving, and the annual saving is dominated by self-consumption. Electricity used on site displaces power bought at the full import rate, while exported electricity earns considerably less. Two identical arrays can pay back years apart purely because one site uses more of what it generates.
- Self-consumption share: the single strongest driver of payback
- Import tariff: the higher the current unit rate, the faster the payback
- Installed cost per kWp: falls as system size grows
- Tax treatment: Full Expensing and capital allowances cut the net cost for limited companies
- Export income: a useful top-up, but rarely the main driver
A worked example
A 250 kWp system costing £200,000 installed, generating around 220,000 kWh a year with 80% used on site at an import rate of 24p/kWh, saves roughly £42,000 a year before export income. That is a simple payback of about 4.8 years, or around 3.6 years after Full Expensing at a 25% corporation tax rate. Every real project needs modelling from the site's own half-hourly data.
What lengthens payback
Low daytime demand, a cheap existing import contract, heavy shading, an export-limited grid connection and roof remediation works all push payback out. None of these is necessarily a reason not to proceed, but they should show up honestly in the model rather than being discovered after signature.
Related reading
FAQ
Is the payback period guaranteed?
No. Payback is a modelled figure based on generation forecasts and assumed energy prices. A good proposal shows conservative, central and optimistic cases so the decision rests on a range, not a single number.
Does a PPA have a payback period?
Not in the same sense. With a £0-upfront PPA there is no capital to recover; savings start from the first bill because the PPA rate sits below the import price.
What happens after the payback period?
The system keeps generating for 25 years or more with modest maintenance costs, so the years after payback are where the lifetime return is made.
Calculate the likely payback for your site
Send us your site details and electricity profile. We will model an indicative commercial solar payback period using your consumption pattern, tariff and likely system size. Prefer to explore numbers yourself first? Run the calculator or contact us directly.
- Site-specific payback range
- Savings and self-consumption estimate
- Key assumptions shown clearly