How Much Do Commercial Solar Panels Cost — By Your Electricity Bill (2026)

When a business owner asks how much do commercial solar panels cost in the UK, the honest answer is "it depends" — but it depends on one thing far more than any other: how much electricity you already use. A well-designed commercial system is sized to your consumption, not your roof. Oversize it and you export cheap power for pennies; undersize it and you leave savings on the table. So the smartest way to estimate the solar system cost for my business is to start with your annual electricity spend and work backwards.

This guide takes the figure straight off your bill, converts it into a sensible system size in kilowatts-peak (kWp), and gives you a realistic price band for 2026. We use the same UK-2026 benchmark throughout: installed commercial solar runs roughly £0.75–£1.05 per watt, or £750–£1,050 per kWp. Larger systems sit at the cheaper end of that range; smaller ones at the top.

Sizing from your bill: the quick method

A commercial rooftop array in the UK generates somewhere between 800 and 1,000 kWh per kWp per year depending on region — roughly 1,000 in the south, 950 across the Midlands, 880 in the north and 800 in Scotland. Self-consumed solar typically displaces grid electricity costing 25–35p/kWh for most businesses on 2026 tariffs. So a kilowatt-peak of solar is worth real money only to the extent you use the power on site during daylight.

The practical sizing rule: pick a system that covers 30–60% of your annual consumption, weighted toward whatever you draw between roughly 9am and 4pm. That band keeps self-consumption high and payback short. The three scenarios below show how that plays out at different bill sizes.

Scenario 1 — £20,000/year electricity bill (~50–80kWp)

A £20k annual bill at, say, 28p/kWh implies around 70,000 kWh of consumption. A system in the 50–80kWp range suits most businesses at this level — a busy office, a small manufacturing unit, a care home, a retail showroom or a medium warehouse with decent daytime load.

Metric	Figure
System size	50–80 kWp
Indicative installed cost	£45,000–£75,000
Annual generation	~45,000–75,000 kWh
Typical simple payback	4–7 years
Payback after AIA tax relief	3–4.5 years
Indicative IRR	15–25%

At this size the price band is wide because installation complexity matters most when the array is small: a simple single-roof job with easy cable runs lands near £750/kWp, while a multi-roof site needing scaffolding, a new DNO connection or roof remediation pushes toward £1,050/kWp. If most of that 70,000 kWh is consumed in daylight, a 60kWp system can realistically cover 35–45% of the bill from year one.

Scenario 2 — £50,000/year electricity bill (~120–150kWp)

A £50k bill points to roughly 175,000 kWh a year. Here you are firmly in the 120–150kWp bracket — typical of a mid-sized factory, a large distribution warehouse, a hotel, a food-production unit or a multi-let commercial estate. This is the size where unit economics start to look genuinely compelling, because fixed costs (design, DNO application, scaffolding mobilisation) are spread across far more panels.

Metric	Figure
System size	120–150 kWp
Indicative installed cost	£96,000–£150,000
Annual generation	~110,000–150,000 kWh
Typical simple payback	4–6 years
Payback after AIA tax relief	3–4.5 years
Indicative IRR	15–25%

For reference, a round 100kWp system — a common benchmark — costs roughly £75,000–£105,000 and produces around 90,000–100,000 kWh a year. Scale up to 150kWp and you are looking at the lower per-watt figures, with installed cost approaching £1,000–£1,050 per kWp only if the site has awkward access or a weak grid connection. At this consumption level, battery storage often earns its keep too, shifting surplus midday generation into early-morning or evening load and lifting self-consumption above 50%.

Scenario 3 — £100,000+/year electricity bill (250kWp and up)

A six-figure bill — £100k or more — means consumption north of 350,000 kWh and a system of 250kWp upward. This is the territory of large manufacturers, cold-storage operators, data-adjacent facilities, big logistics hubs and energy-intensive processors. At this scale per-watt pricing reaches its floor, comfortably around £750/kWp, and the project may qualify for an Industrial Energy Transformation Fund (IETF) grant covering 30–60% of eligible capital for qualifying industrial sites.

Metric	Figure
System size	250 kWp+
Indicative installed cost	£187,500–£300,000+ (per 250–300kWp)
Annual generation	~200,000–300,000+ kWh
Typical simple payback	4–6 years (faster with IETF)
Payback after AIA tax relief	3–4.5 years
Indicative IRR	15–25%

Projects above 250kWp usually require a more involved Distribution Network Operator (DNO) application — a G99 connection rather than the lighter-touch process for smaller arrays — and that timeline (and any export-limitation requirement) should be priced into the quote, not discovered later. Where on-site daytime demand can absorb most generation, these systems deliver the strongest absolute savings in the portfolio simply because the volumes are so large.

Commercial solar price per kW — what actually moves it

The commercial solar price per kW is not a fixed number, and understanding what swings it within the £750–£1,050/kWp band helps you read a quote critically:

• System size. The biggest lever. Fixed costs — design, scaffolding, DNO fees, project management — are diluted across more panels, so a 250kWp array costs far less per watt than a 50kWp one.
• Roof type and access. A simple, strong, south-facing trapezoidal metal roof is cheapest. Fragile asbestos-cement, flat roofs needing ballast, or anything requiring extensive scaffolding or fall-arrest adds cost.
• Grid connection. A straightforward connection is cheap; a constrained network needing reinforcement or an export-limitation device adds both cost and time.
• Mounting and inverters. Ground-mount and car-port canopies cost more per kWp than rooftop. Inverter choice (string vs optimised) and DC oversizing also shift the figure.
• Half-load extras. Battery storage, EV charging, monitoring and electrical upgrades are genuinely valuable but should be itemised separately, not buried in the headline price.

If you want to dig deeper into how these factors interact for your specific site, our detailed breakdown of commercial solar panel cost walks through each driver with worked figures. Remember too that panels degrade only about 0.5% per year, so a system specified today will still be producing roughly 90% of its original output after two decades — which is why payback periods of 4–7 years translate into 15–20+ years of near-free generation.

The tax and export picture

Two financial mechanisms materially shorten payback and belong in any honest appraisal. First, the Annual Investment Allowance (AIA) lets a profit-making business deduct 100% of qualifying solar capital expenditure against taxable profits in the first year — worth roughly a 25% cash benefit at the 25% main rate of corporation tax. That alone pulls a 5-year simple payback down toward 3.5–4 years. Second, the Smart Export Guarantee (SEG) pays you for surplus power exported to the grid, typically 8–20p/kWh depending on supplier and tariff — useful, but always worth far less than the 25–35p you avoid paying by self-consuming, which is why correct sizing beats over-sizing every time.

What a fair fixed-price quote contains — and the red flags

The strongest signal of a trustworthy installer is a quote you can actually interrogate. A fair commercial proposal should include:

• A fixed, all-in price with scaffolding, DNO/G99 application, electrical works and commissioning itemised — not "from £X" or a per-panel teaser.
• A modelled generation figure in kWh/year, ideally referenced to a recognised tool (e.g. PVGIS or MCS methodology) for your postcode and roof orientation.
• A self-consumption assumption stated explicitly — savings hinge on it, and an optimistic 90% figure on a 9-to-5 office is a warning sign.
• Equipment specifics: panel make and wattage, inverter model, and the product and performance warranties.
• MCS certification where SEG payments are intended, plus clear workmanship and structural sign-off.
• A realistic timeline that accounts for DNO approval, which can take weeks to months on larger systems.

Red flags include: a price that ignores your roof structure or grid constraints; savings projections that assume 100% self-consumption; pressure tactics or "today only" discounts; reluctance to itemise; quoting export income (SEG) as if it were the main return; and any claim of guaranteed grants without an eligibility check. A credible installer sizes to your bill, shows their working, and gives you a number you can take to your accountant.

The bottom line: read your annual electricity bill, divide your kWh by the regional yield, aim to cover 30–60% of daytime consumption, and apply £750–£1,050/kWp. That gives you a defensible estimate before a single salesperson walks the roof — and a baseline to judge every quote you receive against.