How much do solar panels for commercial property cost?

The honest answer to "what does solar cost for a commercial building?" is that it depends on the size of system your roof and your electricity bill justify, not the building type alone. A small office install starts around £20,000 for roughly 25 kW. A 250 kW light-industrial roof runs up to about £225,000. Most commercial property owners land somewhere in between. What follows is the real pricing we use across UK installs, the financing routes that mean you rarely pay the headline figure from your own cash, and the hidden line items cheaper quotes leave out.

Cost per kW by system size

Solar gets cheaper per kilowatt as the system grows, because the fixed costs of scaffolding, design, DNO paperwork, and mobilisation get spread across more panels. For 2026 these are the bands we work to on commercial roofs:

• Below 100 kW (small offices, retail units, showrooms): £900 to £1,300 per kW. A 50 kW office system lands around £50,000 to £65,000 before tax relief.
• 100 to 250 kW (light industrial, larger mixed-use, garden centres): £800 to £1,000 per kW. A 180 kW unit comes in near £160,000.
• Above 250 kW (multi-building estates, large warehouses): £700 to £900 per kW where the roof structure cooperates.

Those figures include panels, inverters, mounting, cabling, isolation, commissioning, and monitoring. They assume a sound roof in reasonable condition with an electrical supply that can take the system without a major upgrade. The two biggest swing factors are roof condition and grid headroom, both covered below.

Price ranges by commercial property type

Different commercial buildings carry different load profiles, roof structures, and planning constraints, which moves the economics. Offices align beautifully with generation because the lights, IT, and HVAC all run during daylight. Light industrial units on steel-portal roofs are the cheapest per kW because clip-fix mounting is fast. Retail frontages in conservation areas sometimes push the array to the rear roof, trimming yield. The card grid below the prose sets out the typical system size, project value, and payback for each commercial property type we install.

Financing: you rarely pay the sticker price

Three routes cover almost every commercial install, and most owners never write a single large cheque.

Cash purchase with 100% Annual Investment Allowance. Solar PV qualifies as plant and machinery, so a profitable limited company can deduct the full cost from taxable profit in year one under 100% AIA, up to the £1m annual cap that almost no SME install reaches. At current corporation tax, an £80,000 install costs roughly £60,000 after relief. You can read HMRC's own guidance on capital allowances before you commit. Cash purchase produces the best lifetime return because you own every kilowatt-hour outright.

Asset finance over 5 to 7 years. This is the route most commercial property owners choose. You spread the cost across a fixed monthly payment that is usually lower than the electricity bill saving from day one, so the project is cash-flow positive in month one. You replace a rising grid bill with a fixed finance payment, then own the asset outright at the end of term. A £160,000 light-industrial system financed over six years typically nets positive cash flow even before the loan clears.

Power Purchase Agreement (PPA). A funder installs and owns the system on your roof at zero capex to you, and you buy the solar electricity it generates at a fixed rate below grid retail. You save from day one with nothing on your balance sheet. The trade-off is a smaller lifetime saving than ownership, and a long contract, but for capex-constrained businesses it removes the only real barrier. We model all three routes for every quote so you can compare like for like.

How payback is actually measured

"Payback" gets thrown around loosely. We give you four numbers so you can judge the project properly:

• Simple payback: years for cumulative savings to equal the net install cost. For most commercial roofs this is 5 to 8 years. Daytime-heavy sites with high self-consumption hit the lower end.
• IRR over 25 years: the internal rate of return treating the system as an investment. Well-sited commercial installs model at 12% to 16%, which beats most other uses of the same capital.
• NPV: the discounted lifetime value in today's money, useful when comparing solar against another capital project.
• LCOE: the levelised cost of every kilowatt-hour the system produces over its life, typically 4 to 7p, against a grid retail price north of 30p.

That LCOE gap is the whole story. You are swapping 30-plus pence grid units for self-generated units that cost you single digits.

The hidden costs cheaper quotes leave out

A quote that only lists panels and inverters is hiding the items that actually move the budget. Be sure yours includes:

• Roof condition and re-roof. Many pre-2000 commercial roofs are asbestos cement and cannot take a retrofit array. The right move is often a combined re-roof to profiled steel or membrane, then PV on the new deck. The solar business case frequently pays for the re-roof, but it must be priced honestly up front, not discovered later.
• DNO grid connection. Most commercial sites under 100 kW use a G98 application, generally cleared in 4 to 8 weeks. Above 100 kW you need a G99, where Distribution Network Operator timescales run 6 to 18 months and may carry a reinforcement cost if local capacity is tight.
• Structural survey and any strengthening. A one-day structural and electrical survey confirms the roof can carry the load. Older or lightweight roofs occasionally need bracing.
• Electrical infrastructure. Single-phase supplies cap practical PV around 13 kW. A three-phase upgrade may be needed for larger arrays and should appear as a clear line, not a surprise.
• Scaffolding, access, and isolation. Tall or awkward roofs cost more to access safely.

Cost against your current grid bill

The reason the numbers work is that commercial electricity has roughly doubled since 2021. The average business now pays 30 to 55p per kWh on a fixed contract. A typical commercial property type generates self-consumed solar at a lifetime cost in the single pence. Any surplus is paid for under the Smart Export Guarantee, currently 4 to 15p per kWh depending on supplier. Sites without 24/7 occupancy, such as offices and retail, tend to export 25 to 45% of what they generate, which adds a meaningful income strand on top of the bill saving.

Timeline and cash-flow profile

From signed contract to a commissioned system runs 8 to 16 weeks for installs under 100 kW, with the DNO connection usually the long pole. On asset finance the cash-flow profile is the appealing part: the monthly finance payment starts roughly level with, or below, the bill saving, so there is no painful dip before the returns arrive. We map your exact cash-flow month by month before you sign, and we share the full PVSyst yield model behind every figure rather than asking you to trust a round number on a clipboard.