How much does commercial solar cost in the UK?

What goes wrong, and what does it cost?

The usual mistake is comparing quotes per kWp when each quote covers a different scope, so the cheapest headline price is often the one with costs left out.

The board is asked to approve a quote nobody can compare. One installer says £720 per kWp, another says £950, and nobody can say why.

The real mistakes behind that gap are specific, and each one costs money.

• Using the wrong benchmark. The DESNZ £1,262 per kW figure is for 10 to 50 kW systems. It is a different size class from a 200 kWp roof, and quoting it as the price of a large roof overstates the cost.
• Believing VAT is 0%. Some installer pages say commercial solar qualifies for zero VAT. HMRC Notice 708/6 limits the 0% relief to residential accommodation and buildings used solely for a relevant charitable purpose ⁵. On a £200,000 system, assuming 0% hides £40,000 of VAT that your business must pay first and reclaim later, if it is VAT-registered.
• Comparing different scopes. Roof type, scaffolding, the number of inverters and the grid application all move the price. A quote that leaves out scaffolding or the G99 application looks cheaper and is not.
• Ignoring inverter replacement. Inverters typically need replacing after 10 to 15 years, at £2,000 to £10,000 according to OVO ³. A 25-year model that leaves it out is overstated.
• Mixing kWp with kW AC. kWp is the panel (DC) rating. A quote in kW AC describes the inverter output, so the same roof gives two different numbers.

Each mistake is cheap to avoid before signing and expensive to find afterwards. Our guide to how to compare commercial solar quotes shows how to put every quote on one basis.

How much does commercial solar cost per kWp in the UK?

Installer sources quote roughly £700 to £1,100 per kWp ex-VAT for commercial systems of 100 kWp and above, and no official source covers that size.

DESNZ publishes the official UK small-scale solar PV cost data. It is built from the MCS Installation Database, and its size bands stop at 10 to 50 kW ¹. It has nothing for a 100 kWp or 500 kWp roof.

DESNZ also reports on two bases. Declared net capacity gives £1,262 per kW for 10 to 50 kW systems in 2025/26. Total installed capacity gives £1,204 per kW. After inflation, the 10 to 50 kW median fell 3% on the first basis and 4% on the second compared with 2024/25.

Above 50 kW, buyers rely on installer ranges. OVO gives £700 to £1,100 or more per kWp for 100 kW and above, with costs correct as of April 2026 ³. Solar4Good gives £800 to £850 per kW ex-VAT for a 100 kW system, about £80,000 to £85,000 ⁴. These sources are installers or lead-generation sites with an interest in the sale, and they do not publish the data behind their numbers.

No public source we found gives prices for systems of 1 MW and above, so this guide gives none.

How much does a 100, 250 or 500 kWp system cost in total?

On Spirit Energy's 2026 ranges, a 100 kWp system costs £75,000 to £105,000 ex-VAT, a 250 kWp system £180,000 to £250,000 and a 500 kWp system £350,000 to £480,000.

The price per kWp falls as the system gets larger in Spirit Energy's ranges. The table shows those ranges, with other public sources alongside ².

Spirit Energy publishes total installed cost ranges. The per-kWp column divides those totals by system size. Treat the ranges as a planning guide for a first board discussion, not a quote. A tender on your actual roof replaces them with comparable prices.

What makes two quotes for the same roof differ?

Quotes for the same roof differ mainly because of roof type, scaffolding and access, the number of inverters, grid connection work and any roof repairs, and they should be itemised so you can see which applies.

OVO and Solar4Good name overlapping drivers ³⁴.

• Roof type. Ballasted flat-roof framing and rail systems on pitched roofs are priced differently, and a complex roof adds labour.
• Scaffolding and access. Tall buildings and awkward access raise the cost before a panel is fitted.
• Inverters. The number and type of inverters changes the equipment line and the replacement cost later.
• Grid connection. Electrical connection upgrades and the DNO application under G99 add cost and time. Solar4Good gives 6 to 12 weeks for G99 approval. OVO says the G99 application is included in installer quotes, so ask whether yours is.
• Roof works. Existing electrical infrastructure and roof condition matter. A roof that needs repair or over-cladding costs more than a sound one.

No public source we found gives a typical G99 application fee or DNO connection charge. Business Solar Check, a lead-generation site, puts DNO fees at about £1,000 to £10,000 or more, without giving a method ⁶. Ask each installer to state them separately. Our guide to timeline and grid connection covers G98 and G99 in more detail.

Is VAT charged on commercial solar panels in the UK?

Yes, commercial solar installation is standard-rated at 20% VAT, and the 0% rate applies only to residential accommodation and certain charitable buildings.

HMRC Notice 708/6 sets out the 0% relief for energy-saving materials. It covers residential accommodation and, from 1 February 2024, buildings used solely for a relevant charitable purpose ⁵. The notice does not name offices or factories, so solar on those buildings is not covered by the relief.

Solar4Good also states that commercial solar carries 20% VAT and that VAT-registered businesses can usually reclaim it ⁴. Check your reclaim position with your accountant, including any partial exemption. This guide is not tax advice.

Prices in this guide are ex-VAT. Check that every quote you receive states whether VAT is included.

When is a cost comparison not worth the effort?

A formal cost comparison is not worth it for a small or simple system, or when you already hold comparable quotes and trust your installer.

If your roof is small, simple and well within the 50 kWp range, a local MCS installer and one or two quotes may be enough. The price spread between installers matters most as system size grows, because a spread of £100 per kWp is £25,000 on 250 kWp.

If you already hold three quotes on the same specification and trust one installer, a further tender may add little. If the roof is leased with a short term remaining, or daytime demand is low, the cost question comes second to whether solar suits the site. Our guide on site suitability covers those checks.