Commercial solar for warehouses

Warehouse roofs are usually the best commercial surface for solar in the UK: broad, unshaded and structurally simple. As a planning rule of thumb, a rooftop PV array needs about 7 m² of usable roof per kWp once you allow for spacing, walkways and edge set-backs.² On that basis:

• A 50 kWp system needs roughly 350 m² of roof.
• A 100 kWp system needs roughly 700 m².
• A 250 kWp system needs roughly 1,750 m².

Most single-let distribution units comfortably host 50–250 kWp. The practical limit is rarely the roof area — it is more often roof age and condition, structural loading (thin-gauge metal decks and asbestos-cement sheets need checking), and how much power you actually use on site. A competent installer will confirm the roof can carry the array and that the covering has enough service life left, so you are not paying to remove and refit panels during a re-roof.

Size the system to your daytime demand rather than your total annual use. See the worked figures on our size pages: 50 kW, 100 kW and 250 kW.

Solar only pays well when you use the electricity yourself. Every unit you self-consume displaces a unit you would otherwise buy at roughly 25p/kWh¹; every unit you export earns far less under the Smart Export Guarantee — commonly around 4–8p/kWh depending on your supplier and tariff.⁴ So the share of generation you consume on site (your self-consumption rate) is the single biggest driver of return.

Warehouses score well here. The load profile is daytime-weighted and reasonably steady across the working week: lighting, forklift and pallet-truck charging, roller doors and dock levellers, compressors, and — in chilled or cold-store units — significant refrigeration that runs through the sunny hours. That aligns neatly with the solar curve, so a well-sized warehouse system typically self-consumes 60–85% of what it generates.

• Chilled / cold-store or 24/7 operations push toward the top of that range, or higher.
• Single-shift, lightly-serviced sheds sit nearer the bottom, and may benefit from a battery to capture midday surplus for later use.

These percentages are typical estimates; your real number depends on shift patterns, equipment and seasonality, which a site survey will establish.

A mid-size distribution warehouse might run an annual electricity bill in the region of £20,000–£60,000 at 2026 business rates,¹ so displacing a large slice of daytime consumption is material. The table below is an illustrative estimate for a typical warehouse, before any tax relief.

Two things move these numbers in your favour and are not shown above. First, electricity price inflation: if unit rates rise, every self-consumed unit is worth more, shortening payback. Second, the 50% first-year allowance (see below), which cuts your effective net cost in year one. On these assumptions the simple return on investment is broadly 15–25% a year for a warehouse-scale system — but treat that as an estimate to be confirmed by a survey and your accountant, not a guarantee.

Two tax points are widely misunderstood, so be precise with your accountant.

VAT is 20%, not 0%. The 0% VAT rate on solar applies to domestic / residential installations only, and is due to run until 31 March 2027.⁶ A commercial warehouse installation is standard-rated at 20% VAT. In practice a VAT-registered business normally reclaims that input VAT in the usual way, so it is a cash-flow item rather than a permanent cost — but do not assume 0%.

Capital allowances: the 50% first-year allowance. Solar PV is treated as special-rate plant and machinery, so it does not qualify for 100% full expensing (that is for main-rate assets). Instead, companies can claim the 50% first-year allowance on qualifying new special-rate expenditure — deducting half the cost against profits in year one, with the balance written down at the 6% special-rate pool rate thereafter.⁵ This measure sits alongside full expensing and has been made permanent. Alternatively, the spend may fall within your Annual Investment Allowance (100% up to £1m). Which route is best depends on your other capital spend and profit position, so confirm the treatment with your accountant.

Compared with other commercial buildings, a warehouse has a distinct, and generally favourable, solar profile:

• Large, unshaded roof. Few rooflights or plant obstructions relative to floor area, so you can fit a big array — often more than the site needs, which opens up export or future EV/battery load.
• High, daytime-matched self-use. Operations run through daylight hours, so a strong share of generation is used on site rather than exported at a lower rate.
• Growing electrical load. The shift from LPG/diesel forklifts to electric MHE, plus EV charging for vans and HGVs, is pushing warehouse daytime demand up — which raises self-consumption and improves the case over time.
• Roof and grid checks. The main watch-items are roof age/condition and structural capacity, and — for larger systems — the DNO grid connection (a G99 application), which can affect timescales and, occasionally, export limits.
• Tenure. If you lease the unit, you will need landlord consent and enough lease term (or a roof-lease / PPA structure) for the investment to make sense.

An MCS-certified installer⁷ assesses all of this at survey stage. Deciding whether to buy outright or use a power purchase agreement is a separate question — see buy vs PPA.

The economics turn on when you use power versus when the sun shines. Warehouses do well; some sectors need a battery or an export strategy to match. Indicative, typical ranges:

The numbers on this page are anchors, not a quote. The only way to know your real payback is a site-specific survey covering your roof, your metered load profile and your current tariff.

1. Pull your usage. Get 12 months of half-hourly (HH) data from your supplier — it reveals your true daytime consumption and self-consumption potential.
2. Decide buy vs PPA. Buying captures the full saving and tax relief; a PPA needs no capital but you buy the power at an agreed rate. See how to choose an installer.
3. Get one matched quote. PlutoHome introduces you to a single MCS-certified commercial installer⁷ — not five chasing calls — to survey the site and give you costed figures to check with your accountant.

Request your matched commercial-solar quote, or read the full commercial solar hub.