50kW commercial solar — cost, ROI & payback

A 50kWp system sits in the middle of the commercial range, where the price per kWp falls as systems get bigger. Small 10kW installs run at roughly £1,100 to £1,300 per kWp, while 250kW systems can reach £650 to £750 per kWp. At 50kW, 2026 market pricing is typically around £850 to £1,000 per kWp, putting a fully installed system at £42,000 to £50,000 excluding VAT.¹ The central estimate used on this page is £45,000.

That price is turnkey: modules, inverters, mounting, cabling, the DNO/G99 grid application, scaffolding, installation labour and MCS commissioning. It does not include battery storage, which is a separate decision. The breakdown below shows where the money typically goes for a £45,000 system.

A well-oriented UK system generates roughly 950 kWh per kWp per year, so a 50kWp system produces about 47,500 kWh annually — enough to cover a meaningful share of a daytime business's electricity.⁶ The value comes mostly from self-consumption: every unit you use on site avoids buying that unit from the grid.

Commercial self-consumption typically runs between 60% and 85% depending on how well your demand lines up with daylight. A warehouse or office that operates through the day sits at the higher end; a site that peaks in the evening sits lower. We model a typical 75% here. Self-consumed units save the grid import price — the DESNZ non-domestic average was 24.14 p/kWh in Q1 2026.¹ Units you export earn a Smart Export Guarantee payment, typically a few pence per kWh for a business tariff.⁵

The higher your import price and the more power you use in daylight hours, the stronger the case. A site paying above the average, or running through the day, would see a larger saving; an evening-heavy site less, unless a battery shifts the surplus.

On the central estimates — £45,000 installed and about £9,200 of annual benefit — the simple payback is roughly 5 years. After that the system keeps generating largely for free, with modules generally warranted to hold most of their output for 25 years and inverters typically replaced once in that window.

Over a 25-year life, with a conservative allowance for gradual panel degradation and no assumed rise in electricity prices, the estimated net benefit is around £160,000 to £190,000 after the upfront cost — a 25-year return on investment of roughly 350% to 400%. If electricity prices rise over the period, both the saving and the ROI increase; if you self-consume less, they fall.

Weighing owning outright against a funded route with no upfront cost? See buy vs PPA for how the two compare on lifetime value and control.

Two tax points materially change the real cost, and both are worth confirming with your accountant.

Capital allowances. Solar PV is treated as special-rate plant, so it does not qualify for 100% full expensing (that is for main-rate plant). Instead it qualifies for the 50% first-year allowance for special-rate expenditure, which the government has made permanent.² A company can deduct 50% of the cost in year one, with the balance entering the special-rate pool and written down at 6% a year thereafter.³ Most businesses can alternatively use the Annual Investment Allowance for 100% relief up to its cap. On a £45,000 system, a 50% first-year deduction is £22,500, worth £5,625 in year-one tax at the 25% corporation tax rate — which shortens payback further.

VAT. The 0% VAT rate applies to domestic solar installations only, until 31 March 2027.⁴ Commercial solar pays 20% VAT, which a VAT-registered business normally reclaims through its return. Do not budget a commercial project as if it were VAT-free.

A 50kWp array needs about 350 m² of usable roof (roughly 7 m² per kWp), so it suits mid-sized premises with a decent unobstructed roof — think a small warehouse, an industrial unit, a farm building, a medium retail store, a hotel or a school block.

On the demand side, this size fits a business with an annual electricity bill in the region of £12,000 to £25,000-plus that uses much of its power during daylight. If your roof or your load is larger, a bigger array will usually deliver a lower cost per kWp and a stronger return; if smaller, size down.

• Roof area needed: ~350 m²
• Best fit: daytime-operating sites self-consuming 60–85% of output
• Typical bill range: £12k–£25k+ per year

See how the numbers change by sector: warehouse, factory, farm, school, retail and hotel. To compare against other sizes, see the commercial solar hub and cost pages for 30kW and 100kW.

The figures on this page are planning anchors. Turning them into a firm business case needs three things: your actual half-hourly electricity data, a roof survey, and a decision on whether to buy outright or use a funded route.

1. Pull your consumption data so an installer can model real self-consumption rather than a rule of thumb.
2. Decide your funding route — read buy vs PPA to weigh ownership against a no-upfront-cost agreement.
3. Choose a certified installer — our how to choose guide covers MCS certification, warranties and the questions that matter.

PlutoHome is a neutral introducer. We are not the installer and do not install, finance or own systems. We match your business with one MCS-certified commercial installer suited to your site — not a list of five to chase you.