Solar for chilled and frozen food distribution centres

Why a distribution centre can suit rooftop solar

When people think about solar panels for cold storage they often picture a single chilled warehouse, but in practice the cold chain runs through the distribution centre too. A modern DC carries ambient and chilled bays under one roof, with materials handling equipment charging through the day and refrigeration and lighting drawing power around the clock. That mix of loads is what can make a distribution centre a good site for rooftop solar. Much of the electricity your panels generate could be used on site against a genuine daytime baseload rather than exported at a lower price, and self-consumption is the single biggest driver of solar payback. The site's simple model gives an illustrative payback of around 5.5 years for a DC array (assumed tariff and self-consumption; not a quote), and the chilled element of the building tends to help the case because refrigeration runs whether the order book is busy or quiet.

Electricity cost is part of the picture. TNUoS and BSUoS network charges are a component of the delivered electricity price, change each year and land on the logistics profit and loss, while customer Scope 2 and Scope 3 mandates from the likes of the Amazon Climate Pledge, Tesco net zero and Unilever CTAP flow through to 3PL operators and tenants. A distribution centre sits within that supply chain, so every kWh generated and used on site avoids the energy and network components of the bill, and on-site generation can provide auditable evidence of carbon reduction for customer audit packs. The buildings themselves often suit PV: large clear-span steel-portal roofs with relatively few obstructions, subject to a structural check. Because large roofs carry real engineering and fire-safety questions, ask the site's insurer and a fire-protection engineer about roof loading, clearances and sprinkler compatibility before design, which is why getting the engineering right matters so much.

What a typical install looks like and how it is sized

A distribution centre system typically sits in the 500 to 3,000 kW range, which is roughly 920 to 5,500 panels across about 3,000 to 18,000 square metres of clear-span steel-portal roof. A system that size generates in the region of 460,000 to 2.75 million kWh a year and saves somewhere between 106 and 633 tonnes of CO2 annually. The roof should never simply be filled. Sizing on a warehouse is unusual because roof area is rarely the binding constraint; the real limits are daytime baseload and DNO capacity. The half-hourly meter data should always be pulled first, because many distribution centres have a surprisingly low daytime baseload between order peaks, and an array sized to an optimistic maximum would export too much at a poor price.

The MHE charging fleet is the key to a good DC design. Forklift and reach-truck charging provides excellent daytime self-consumption, and where that charging coincides with the solar peak the system can be sized more confidently. The chilled and frozen bays add a steady round-the-clock baseload underneath the daytime peaks, which lifts self-consumption further still. For pure daytime operations of roughly 06:00 to 18:00, a battery is increasingly economic at scale and lets midday generation cover the early evening tail. M1, M6 and A1 corridor sites tend to be the highest priority because the buildings are large, modern and structurally suited to PV, and because the operators on those corridors feel the customer sustainability pressure most acutely. A sound proposal models the array against your real load curve, not a generic warehouse profile, and presents the sizing logic openly so you can see why the system is the size it is.

Costs, payback and tax relief

In the site's illustrative model a distribution centre project lands between £350,000 and £2.4m depending on system size and roof area, at an illustrative £700 to £900 per kW (a modelling assumption, not a quote or a market survey). Illustrative simple payback sits near 5.5 years in the site's simple model (assumed tariff and self-consumption; not a quote), after which the electricity is effectively free for the rest of the system's long life. The biggest financial lever is tax. Solar PV qualifies as plant and machinery, so the 100% Annual Investment Allowance lets most warehouse installs claim the full cost as relief in year one up to the £1m cap, with a 50% First Year Allowance on qualifying spend above that, subject to current legislation. As an illustration, for a limited company the Annual Investment Allowance relief is worth up to a quarter of the project value back as tax saved in the first year, which would materially shorten the effective payback.

The Smart Export Guarantee applies to generators up to 5 MW and pays for any surplus you export at a rate the supplier sets, so compare each supplier's published SEG tariff; on a busy DC with chilled load much of the generation is expected to be consumed on site and export is modest, so it is a minor line. Where the building is leased, the tax shield from capital allowances can become a negotiation point with the operator or landlord, and a PPA can fund the system with no capex at all. Our cost guide sets out worked numbers by system size so you can see how the figures move with scale.

Funding routes in detail

There are several ways to fund a distribution centre system, and the right one depends on whether you own or lease the building. Capital allowances are the headline relief: most DC installs can claim the full cost in year one under the Annual Investment Allowance, with the 50% First Year Allowance covering qualifying spend above the cap, and combined with PPA finance the tax shield can become a negotiation point with tenants or operators. If your building sits within a designated UK Freeport or Investment Zone, it is worth checking whether Enhanced Capital Allowances apply to qualifying new plant and machinery.

For tenants, the Green Lease Clause and tenant capital recovery route is a common one. It is not a grant, but it unlocks your ability to install solar on a leased building, and a lease addendum aligned with the BBP Green Lease Toolkit is the usual route, which many institutional landlords will consider. Consent timing varies with the landlord and the lease, and is worth raising early. The Smart Export Guarantee contributes for any exported surplus. The Industrial Energy Transformation Fund closed in July 2025 and no successor fund is planned, so it cannot be counted on; check GOV.UK for any scheme open now. It is worth working through every route that applies to your site, so nothing is left on the table.

Compliance and sector considerations

Sprinkler compatibility needs to be settled before design: ask the site's insurer and a fire-protection engineer about roof loading, clearances and sprinkler compatibility, so the layout is built around the sprinkler heads, not the other way around. Insurer engagement is essential, and insurer pre-design review should be completed so that sign-off is obtained before anything is fabricated, which protects your cover. Emergency access routes should be maintained per the fire risk assessment, and where fire detection integration is involved the work should meet BS 5839-1 and SPF1981 v3 fire safety design.

In England, roof-mounted solar on a non-domestic building is normally permitted development under Class J of Part 14 of the GPDO 2015; an array above 50 kW, as a distribution centre array usually is, needs the council's prior-approval decision on design and external appearance, including glare. Listed building constraints are rare for logistics buildings, and a conservation area does not remove Class J for a roof, although a listed building or its curtilage is excluded. On the grid side, G98 'connect and notify' covers up to 16 A per phase (3.68 kW single-phase, about 11 kW three-phase); above that a G99 application and the network operator's approval before connecting are needed, and at distribution-centre scale it is always G99. Larger systems may need network reinforcement; many warehouses retain generous capacity from past industrial use, but the capacity should always be confirmed rather than assumed. Wind loading should be designed to BS EN 1991-1-4 for the specific terrain category, and where chilled bays form part of the building the refrigeration plant remains subject to the F-gas Regulations. Where the building is leased, the tenant capital improvements position in the lease also needs attention, so the legal and technical strands move together.

How this kind of project is typically approached

A sound approach removes the things that usually stall warehouse solar. It starts by pulling the half-hourly meter data so the system is sized for genuine self-consumption rather than an optimistic roof fill. A roof and structural check follows, including a wind-load assessment to BS EN 1991-1-4, before a layout is committed to, and the roof build-up is confirmed so the fixings suit the deck. The G99 grid application is normally submitted early so the DNO clock starts while the survey and design proceed in parallel, which is often the single biggest factor in hitting a target energisation date.

Your insurer should be engaged for pre-design review and sprinkler clearances confirmed before fabrication, so there are no surprises late in the build. Crucially, the building does not need to go offline: roof installation can happen above live operations while MHE, picking and despatch continue normally, and the only outage required is the final grid synchronisation of four to eight hours, which can be scheduled for a weekend or planned shutdown. When comparing proposals, ask what accreditations and insurance the installer holds and ask to see the evidence (MCS covers systems up to 50 kW, which is below the scale of most cold-store arrays), and ask how the workmanship is warranted.

An illustrative example

As an illustrative composite (not a real project) built from the site's modelling assumptions: a national 3PL operating a large M1-corridor distribution centre serving major retail chains, with an existing electricity spend in the region of £620,000 a year and a tenant on a long FRI lease with green-lease provisions, might install around 1.18 MW of roughly 2,170 panels, which would be expected to generate about 1,090,000 kWh a year. Funded by a PPA with zero capex, self-consumption would be expected to settle near 84%, the annual saving would be expected to sit around £245,000 for a payback close to 5.1 years in the simple model, and the customer audit pack could gain auditable Scope 2 reduction. The figures are illustrative and depend on your building, tariff, roof and funding route.

If your estate mixes ambient and chilled handling, our pages on solar for cold chain warehouses and fulfilment centre solar may also apply. When you are ready, see the cost guide and funding routes, then send an enquiry, or read the cold storage solar FAQs first.