The most common question we get from warehouse operators is also the hardest to answer in one number: what do commercial solar panels actually cost? The honest answer is that cost is best expressed as a £/kWp band, and what matters to you is how that converts to your specific roof and load. This post sets out the average cost of commercial solar panels for a UK warehouse in 2026 — and, more usefully, how to translate it into a figure for your own building.
What is the average cost of commercial solar panels in 2026?
For commercial rooftop systems the prevailing 2026 installed cost sits in an indicative range of roughly £600-£1,200 per kWp, and the figure within that band is driven almost entirely by scale. Small sub-100 kWp systems sit at the upper end because fixed project costs — DNO application, design, scaffolding, commissioning — are spread over fewer kW. Large single-span warehouse roofs land at the lower end thanks to scale and simple, repetitive mounting. A useful rule for warehouses specifically: the bigger and simpler your roof, the closer you get to the bottom of the range. These are indicative ranges to scope a budget, not a quote — the precise figure depends on roof condition, structural capacity and your grid connection.
Cost by warehouse size — roof area to kWp to £
Most guides quote £/kWp but never connect it to the number you actually know: your building size. As a working rule a typical warehouse roof supports about one kWp for every 5-7 m² of usable roof area once you deduct rooflights, walkways, plant and setbacks. Worked through: a ~25,000 sq ft unit carries roughly a 250-400 kWp array; ~50,000 sq ft around 500-750 kWp; ~100,000 sq ft around 1-1.4 MW. Apply the £/kWp bands above and a 500 kWp system lands at roughly £375,000-£475,000 installed, a 1 MW system around £700,000-£800,000. Our full commercial solar panels cost breakdown itemises where every pound goes — panels, inverters, mounting, cabling, DNO works, structural certification and commissioning.
What changes the number most
Three variables move the cost more than anything else. First, DNO grid connection: an unconstrained connection is modest, but a constrained network can require an export limit or reinforcement that adds materially. Second, roof condition: pre-2000 cement-fibre or fragile roofs may need a structural survey or partial re-roof before panels go on. Third, system scale relative to your load: building to fill every square metre when your daytime demand is small means exporting surplus at the Smart Export Guarantee — a voluntary, supplier-set rate, not a fixed national tariff — rather than displacing grid power at full retail price. Sizing to load is usually better value than sizing to the roof.
The number that actually matters: after-tax cost
Headline cost is not net cost. Qualifying solar capex is normally relieved at 100% in year one through the Annual Investment Allowance up to the £1m cap, with the special-rate 50% first-year allowance applying to qualifying spend above that — solar sits in the special-rate pool, so it does not attract main-rate full expensing. For a £750,000 system fully within AIA that is around £187,500 of year-one corporation tax relief at the 25% rate, cutting the net effective cost to roughly £562,500. Against annual savings of £150,000-£180,000 for a well-matched 1 MW system, after-tax payback typically lands in the 3-4 year range.
How to get an accurate figure for your warehouse
An average is a starting point; an accurate cost needs your building. Send us your roof drawing and 12 months of half-hourly meter data and we return an itemised, building-specific cost — with after-tax net cost and a DNO connection estimate — within 7 working days. No charge, no obligation, and if the numbers do not work for your site we will tell you.