Powering Change
Installing since 2010 · 0118 951 4490 · info@spiritenergy.co.uk
Commercial solar in the UK costs between £700 and £1,100 per kWp installed in 2026. That figure includes the panels, inverters, mounting, cabling, installation and commissioning. The price per kWp falls as the system gets larger, because the fixed costs of any project — surveying, scaffolding, grid connection and project management — are spread across more panels. A small rooftop system sits near the top of the range; a large warehouse or ground-mount array sits near the bottom.
Cost per kWp is the figure to compare quotes on, not the headline total. A £400,000 system isn't expensive if it's 500 kWp (£800/kWp); a £40,000 system isn't cheap if it's only 35 kWp (£1,140/kWp). Always divide the total by the system size to compare like for like.
The table below shows typical installed cost ranges by system size, based on the £700–£1,100 per kWp guide. Actual pricing depends on roof type, access, mounting system and grid-connection requirements, so these are indicative ranges rather than quotes.
| System size | Approx. panels | Typical installed cost | Indicative annual saving |
|---|---|---|---|
| 30 kWp | ~65 | £27,000–£33,000 | £6,000–£9,000 |
| 50 kWp | ~110 | £40,000–£55,000 | £10,000–£15,000 |
| 100 kWp | ~220 | £75,000–£105,000 | £20,000–£30,000 |
| 250 kWp | ~550 | £180,000–£250,000 | £50,000–£75,000 |
| 500 kWp | ~1,100 | £350,000–£480,000 | £100,000–£150,000 |
Savings figures assume a business consuming most of its generation on site during daylight hours. Sites that export a larger share of their generation will save less, because export pays a lower rate than the electricity you avoid buying.
A complete commercial solar installation price from Spirit Energy includes the solar panels, inverters, mounting and racking system, all DC and AC cabling, the installation labour, scaffolding and access, system commissioning, monitoring setup, and your MCS certification. We also handle the DNO grid application as part of the project.
The main variables that move the price within the per-kWp range are roof type and condition (flat roofs need ballasted or fixed mounting; older roofs may need remedial work), access and scaffolding requirements, the inverter and panel specification chosen for the site, and whether the grid connection needs reinforcement. Battery storage, if specified, is a separate cost on top.
Most Spirit Energy commercial systems pay back in 3–5 years, and as little as 3 years where on-site daytime demand closely matches generation. Payback is driven by three things: the cost of the system, how much of the generation you use on site rather than export, and your grid electricity price. The higher your current tariff and the more power you use during daylight, the faster the system pays for itself.
This is why businesses that run during the day — manufacturers, warehouses, hotels, care homes, leisure centres — achieve the fastest payback. They consume most of what they generate, displacing electricity they'd otherwise buy at 22–35p/kWh. St Michael's Hospice paid back its 60.2 kWp system in 4 years, and Philip Dennis Foodservice paid back a 695 kWp system in under 4 years.
Recent Spirit Energy commercial projects have delivered internal rates of return (IRR) of 23–45%, with lifetime ROI regularly landing in the 400–700% range over the system's 25-year-plus life. To put that in context, an IRR of 25–30% comfortably exceeds the return on most other capital investments a business could make.
The returns come overwhelmingly from displaced grid imports — the electricity you generate and use yourself — rather than from export income. And because UK commercial electricity prices remain well above the European median and continue to rise, the value of each unit you self-generate tends to increase over time, improving the return across the system's life. Real examples include Philip Dennis Foodservice at a 23% IRR with around £2.4 million projected savings over 25 years, St Michael's Hospice at 30%, and Osbourne Court at 24%.
After payback, typically in years 3 to 5, the system continues generating electricity at a marginal cost of effectively nothing for the remaining two decades or more — which is where the bulk of the lifetime ROI is earned.
For the wider business case beyond the numbers — energy independence, Scope 2 reductions and ESG — see our commercial solar benefits page. For exact figures on your building, Spirit Energy provides a free site-specific financial model showing projected savings, payback and IRR based on 12 months of your energy bills and your roof. There is no cost or obligation.
