Commercial solar in the UK costs roughly £900 to £1,500 per kWp installed, depending on how it is mounted. A pitched warehouse roof is the cheapest at around £900 per kWp; a solar carport is the most expensive at around £1,500, because you are buying a structure as well as a solar system.
Installed cost per kWp
Commercial solar is priced per kilowatt-peak (kWp) of installed capacity. The rate depends mostly on how the panels are mounted, because mounting drives the structural work, the labour and the cabling runs. These are the all-in rates our calculator uses:
| Mount type | Installed cost | Usable area assumed |
|---|---|---|
| Pitched roof | £900 / kWp | 80% of roof area |
| Flat roof | £1,000 / kWp | 80% of roof area |
| Ground mount | £1,050 / kWp | 90% of land area |
| Solar carport | £1,500 / kWp | 85% of parking area |
Carports cost most because you are buying a steel structure as well as a solar system. Ground mount sits between the two: no roof work and simple access, but groundworks, fencing and a longer cable run to the point of connection.
Rates fall as systems get larger. The figures above are typical for systems from 50 kWp upwards; a 1 MWp array will usually come in below them, and a 60 kWp array above.
What that means for a real roof
A 3,200 m² pitched warehouse roof fits roughly 998 panels at 510 W each, or 508.98 kWp, at a modelled installed cost of £458,082. The same roof as a flat roof would be around £509,000. As a carport over an equivalent area of parking it would be around £763,000, though it would also give you covered parking and a natural home for EV charging.
As a rule of thumb for a first sanity check: usable roof area in square metres, divided by about 6.3, gives you the kWp. Multiply by the rate above for the cost.
What the figure includes
- Panels, mounting system, inverters, cabling and protection
- Installation labour and access equipment
- Electrical work up to your existing distribution board
- Commissioning, testing and handover documentation
- The G98 or G99 application to your distribution network operator
What it does not include
- Roof repairs or strengthening. If the roof has less than fifteen years left, you should recover and reroof before installing, not after.
- Grid reinforcement. If your connection cannot take the export, the network operator may quote for works. This is site-specific and occasionally large.
- Battery storage, modelled separately at around £1,000 per kWh of usable capacity.
- Finance costs, if you borrow rather than pay cash.
- VAT, which is normally recoverable for VAT-registered businesses.
Our model does include one inverter replacement in year 13, because inverters typically carry a twelve-year warranty while panels carry twenty-five.
What moves the price
- Size. Fixed costs such as design, scaffolding and connection work spread over more kWp as systems grow.
- Roof condition and type. Standing seam, asbestos cement and fragile roofs each change the fixing method and the access requirement.
- Height and access. A single-storey unit with yard space is cheaper to work on than a city-centre roof with no crane position.
- Cable run. The distance from the array to the point of connection matters more than people expect on large sites.
- Programme. Work that has to happen at night or around production shutdowns costs more.
Because of all of this, an estimate is a starting point for a conversation, not a quotation. A firm price needs a site survey, a structural check and a connection position from your network operator.
Common questions
How much does commercial solar cost per kWp?
Between about £900 and £1,500 per kWp installed, depending on how it is mounted. Pitched roof is cheapest at around £900 per kWp, flat roof around £1,000, ground mount around £1,050 and solar carports around £1,500. Larger systems come in below these rates and small ones above.
Can I reclaim the VAT on commercial solar?
VAT-registered businesses can normally recover VAT on a commercial solar installation in the usual way, so the figures in our calculator are shown excluding VAT. The zero rate that applies to domestic installations does not apply to commercial projects.
What is not included in the installed cost?
Roof repairs or strengthening, any grid reinforcement your network operator charges for, battery storage, finance costs and VAT. Roof condition and grid reinforcement are the two that most often change a project's economics, and both are site-specific.