Commercial solar in the UK — costs, ROI & tax (2026)

Installed cost per kWp falls as the system grows, because fixed items — scaffolding, design, DNO paperwork, MCS certification and commissioning — spread across more panels. The figures below are indicative 2026 ranges, ex VAT, for a straightforward pitched or flat commercial roof¹. Roof area assumes roughly 7 m² per kWp. Treat these as sanity anchors: your quote depends on roof type, height, cable runs, half-hourly load and whether you add battery storage.

The single biggest driver of return is self-consumption — the share of your solar output you use on site rather than exporting. A unit you consume avoids your full import tariff (commonly 22–28p/kWh in 2026); a unit you export earns a Smart Export Guarantee rate, often only 3–15p/kWh⁵. Self-consumed energy is therefore worth roughly three to four times more than exported energy, so systems are sized to daytime demand, not roof space.

Commercial self-consumption typically runs 60–85% depending on sector: a warehouse or office with steady daytime load sits high; a site that is busy only in early mornings or evenings sits lower. Adding a battery lifts self-consumption but changes the payback maths.

This is a worked illustration, not a promise. Across the market, businesses that use most of their output typically see 5–8 year payback, improving once the tax allowances below are applied. See how to choose an installer for the questions that protect these numbers.

You will see "0% VAT on solar" everywhere. That relief applies to domestic and residential accommodation only — homes, flats, care homes, student housing and qualifying charitable buildings. HMRC is explicit that the standard rate applies to installations in commercial premises such as offices, retail units, factories, hotels and similar establishments⁴.

So commercial solar carries 20% VAT. The practical upshot for most businesses is modest: a VAT-registered company normally reclaims that input VAT on its return, so it is a cash-flow item rather than a permanent cost. If your business is not VAT-registered, or makes exempt supplies, the position differs — confirm with your accountant.

Capital allowances are where commercial solar earns much of its return, but the detail matters. Under the first-year allowance rules, full expensing gives 100% relief on main-rate plant. Solar PV, however, is classed as special-rate plant, which does not qualify for full expensing — instead it attracts the 50% first-year allowance, with the remaining balance added to the special-rate pool and written down at 6% per year thereafter².

Companies can alternatively cover qualifying spend using the Annual Investment Allowance, which gives 100% relief up to £1 million a year and can include solar³. Which route is most efficient depends on your wider capital spend and profit position.

These allowances were confirmed as ongoing government measures, but rules and dates change. This is general information, not tax advice — your accountant should confirm what your company can claim before you commit.

There are two common ways to fund commercial solar. Buying outright (cash or asset finance) means you own the system, keep every unit of saving, and claim the capital allowances above — the strongest lifetime return, but you fund the capital and own the maintenance.

A Power Purchase Agreement (PPA) means a third party funds, owns and maintains the system on your roof, and you buy the solar electricity from them at an agreed rate — usually below grid price, with no upfront cost. You get lower bills from day one, but a smaller share of the benefit and a long-term contract to read carefully.

• Own the return, fund the capital → buy outright
• Protect cash, share the return → PPA

The right answer depends on your balance sheet, tax position and how long you will hold the premises. See our full buy vs PPA comparison for the trade-offs side by side.

Roof size, daytime load shape and available area drive the economics as much as system price. The summary below is directional; each sector page carries worked numbers.

Most "free quote" sites sell your details to four or five installers who then compete on your inbox. PlutoHome works differently. We are a neutral introducer: we do not install, finance or own systems, and we take no side. We match your premises with a single MCS-certified commercial installer suited to your roof, sector and load — so you get one considered proposal, not a bidding war.

1. Tell us your premises type, rough roof size and daytime electricity use.
2. We match you to one appropriate MCS-certified commercial installer.
3. They survey and quote against your actual half-hourly data.

MCS certification is the recognised quality standard for solar installations, and we only introduce certified installers⁶. When you are ready, request your exclusive commercial solar quote or read how to choose an installer first.