Solar Panels for Warehouses UK: Ambient vs Chilled Explained

Warehouse roofs offer advantages that few other buildings can match:

• Scale: a 10,000 square metre roof could, in principle, take well over 1MWp of panels, and per-kWp prices fall as systems get larger.
• Simple roof coverings: many modern warehouses have metal sheet or standing seam roofs, which are among the quickest and cheapest to work on.
• Few obstructions: large roofs typically have less plant than offices or factories, although rooflights are common.
• Low pitch: gently sloping or near-flat roofs allow regular layouts, often in east-west rows.

Large commercial systems on simple roofs can fall towards £700 to £850 per kWp in 2026, against £1,000 or more for small systems. That makes the cost per unit of electricity generated on a warehouse roof among the lowest of any building type.

The catch is that a cheap unit of electricity is only valuable if the building can use it or sell it at a good price. A warehouse roof can generate far more than many warehouses consume, and exported electricity typically earns only a few pence per kWh. That is why the type of storage inside the building matters more than the size of the roof above it.

Two warehouses with identical roofs can have completely different solar cases, depending on what they store.

• Chilled and frozen stores: refrigeration runs around the clock and works hardest on hot, sunny days, exactly when solar output peaks. Daytime demand is high and steady, so a large system can be used almost entirely on site. These are among the strongest solar cases of any building type.
• Ambient warehouses: the main loads are lighting, battery charging for forklifts, offices and docks. Daytime demand can be modest, especially with efficient LED lighting, so a roof-filling system would export much of its output.
• Mixed sites: buildings with a chilled section, a pick-and-pack operation or automated handling fall somewhere between.

For a chilled store, the design question is usually how much of the roof can be used. For an ambient warehouse, it is how much of the roof is worth using for the building's own needs, and what to do with the rest.

Ask any installer how they arrived at their proposed system size and self-consumption figure. A proposal that treats an ambient warehouse like a chilled one will overstate the savings considerably.

Indicative 2026 prices for straightforward warehouse rooftop systems, excluding VAT and any roof works:

• 100kWp: £80,000 to £100,000, needing around 500 to 600 square metres of usable roof
• 250kWp: £175,000 to £215,000, around 1,250 to 1,500 square metres
• 500kWp: £325,000 to £400,000, around 2,500 to 3,000 square metres
• 1MWp and above: often below £700 per kWp on large, simple roofs

Typical starting points by warehouse type, before any decision about using surplus roof space:

• Small ambient unit: often 50 to 150kWp, sized to lighting, offices and equipment charging
• Large ambient distribution centre: commonly 100 to 250kWp for the building's own use, unless surplus roof is used another way
• Chilled or frozen distribution: 250kWp to well over 1MWp, depending on refrigeration load

Generation is typically 850 to 1,100 kWh per kWp a year, depending on location, orientation and layout. Our sizing guide explains how to set system size from your half-hourly data.

An ambient warehouse that sizes solar to its own demand may use only part of its roof. The remaining space still has value, and there are several ways to use it:

• Leave it for later: install for current demand, design the layout and grid application to allow a second phase, and add panels when demand grows.
• Electrify the fleet: charging electric vans, and increasingly electric HGVs, during the day can turn a low-demand warehouse into a high-demand one. Plan solar and charging together.
• Supply neighbouring occupiers: on a multi-let estate, a private wire arrangement can sell surplus electricity to adjacent units at a price between their grid rate and the export rate.
• Lease the roof: a third-party investor installs and owns a larger system, paying rent for the roof and sometimes supplying electricity to you. You give up most of the value but carry no cost or risk.
• Export-led systems: where the grid connection allows, a larger system sells surplus under an export agreement. This only works if the export price justifies the extra cost.

Each option involves contracts, metering and grid considerations, so ask installers to model them separately rather than simply filling the roof.

The payback gap between chilled and ambient warehouses is wide. Assume grid electricity at 25p per kWh and exports at 5p.

• Chilled store, 500kWp: costing around £360,000 and generating about 475,000 kWh a year, with 90% used on site. Savings of around £106,900 plus £2,400 export income give about £109,300 a year, a payback of around 3.3 years.
• Ambient warehouse, 500kWp roof-filling system: the same cost and generation, but only 35% used on site. Savings of around £41,600 plus £15,400 export income give about £57,000 a year, a payback of around 6.3 years.
• Ambient warehouse, 150kWp sized to demand: costing around £130,000 and generating 142,500 kWh, with 85% used on site. Savings of around £30,300 plus £1,100 export income give about £31,400 a year, a payback of around 4.1 years.

The smaller ambient system pays back much faster than the roof-filling one, even though it costs more per kWp. These figures are illustrative, and capital allowances can shorten each payback for profitable companies. Our payback guide explains the calculation.

Large warehouse roofs raise specific structural and practical questions:

• Structural capacity: many modern portal-frame buildings are designed efficiently, with limited spare capacity. A racked array adds around 12 to 25 kg per square metre, which many roofs can carry, but a structural engineer must confirm this, particularly for older or lightweight buildings.
• Rooflights: warehouses often have rows of rooflights, which reduce usable area, need protecting during installation and should not be shaded by panels if daylighting matters.
• Asbestos cement: older warehouses may have asbestos cement roofs, which cannot have panels fixed to them. Over-cladding or replacing the roof comes first.
• Roof life: cut-edge corrosion on older metal sheets is common. If the roof will need attention within 10 to 15 years, deal with it before installing panels.
• Drainage and gutters: layouts should keep valley gutters and outlets accessible for maintenance.

Our commercial roof suitability checklist covers each of these checks in detail.

Warehouses often hold large quantities of combustible stock, so insurers pay close attention to rooftop solar on them. Most UK insurers assess commercial arrays against the RISCAuthority RC62 recommendations on fire safety for solar PV.

Points that matter particularly on warehouses include:

• Roof construction: some insurers apply extra conditions where panels sit on composite roof panels with combustible insulation cores.
• Firebreaks and access: large arrays are usually divided into sections with clear gaps, giving access routes and helping to limit fire spread.
• Separation from rooflights and smoke vents: panels should not block smoke ventilation or sit too close to rooflights.
• Cable routes: DC cables inside the building should be routed and protected to reduce risk, with isolation points clearly labelled for the fire service.
• Inspection: regular electrical testing and thermal imaging help find faults before they become dangerous.

Tell your insurer before you sign a contract, and ask for its requirements in writing. Insurer conditions can affect layout and cost, so it is better to know them at the design stage. Tenants should also check the requirements of the landlord's buildings insurer.

Warehouse systems are often large enough to run into grid constraints, especially on industrial estates where several sites share local network capacity. Almost every system needs G99 approval from the network operator, which has up to 45 working days to issue a connection offer on a full application.

On a constrained network, the operator may offer the connection only with an export limit, or require reinforcement at your cost. For a warehouse, the right response depends on the solar strategy:

• Systems sized to on-site demand: an export limit usually costs little, because most output is used in the building anyway.
• Export-led or roof-filling systems: an export limit can undermine the business case, so reinforcement costs need to be weighed against the extra income.
• Future phases and EV charging: plan the connection for the full intended system and future demand from the start where possible.

Ask installers to request both a full-export and an export-limited option, so you can see the cost of each before committing. Our G99 grid connection guide explains the process in full.

Many warehouses are leased, often on full repairing leases, so the occupier may be responsible for the roof but still needs the landlord's consent to install solar. Agree in writing who owns, insures and maintains the system, who is liable for roof damage, and what happens at the end of the lease.

Funding routes for warehouses include:

• Buying outright or asset finance: the strongest long-term return, with the Annual Investment Allowance allowing most businesses to deduct qualifying spend of up to £1 million from taxable profits in the year of purchase.
• Power purchase agreement: large warehouse roofs are attractive to PPA funders, who may offer no-upfront-cost systems with electricity priced below grid rates.
• Landlord-funded solar: some landlords install solar across their estates and sell electricity to tenants.
• Regional programmes: in some mayoral combined authority areas, the Local Growth Fund may support business energy projects. Our commercial solar grants guide explains what is available.

In England, eligible rooftop solar is also exempt from business rates until 31 March 2035.

Give every shortlisted installer the same information so their proposals can be compared fairly:

1. Twelve months of half-hourly consumption data
2. Whether the building is ambient, chilled, frozen or mixed, and operating hours
3. Roof drawings, construction, age and any asbestos information
4. Rooflight and smoke vent locations
5. Insurer requirements and landlord consent, if relevant
6. Plans for fleet electrification, automation or expansion

When proposals arrive, check the self-consumption assumption against your data, the marginal payback of each step up in size, the grid connection position and how the installer will handle fragile rooflights and live operations below. For large roofs, ask for options covering on-site use, future phases and any export or private wire arrangements.

Read more about warehouse installations on our retail and warehousing solar page, and see our guide to comparing commercial solar quotes. When you are ready, compare quotes from up to three MCS-certified commercial installers for your warehouse.