Solar PV for Warehouses: A UK Guide to Roofs, Costs and Grid
A warehouse is close to the ideal building for solar PV. It has a large, flat, unshaded roof and it uses power in daylight hours. Whether a given roof pays back depends on five things: the roof’s structure, your half-hourly demand, the electrical capacity at the site, the grid connection and how you finance it. This guide covers each in turn, then looks at battery storage and at pairing solar with EV charging for vans, HGVs and staff.
TL;DR
Most warehouse roofs can take solar PV, but structure, roof material and electrical capacity must be checked before any design is fixed.
Size the system to your daytime demand, not to the roof. One UKWA-published Midlands example met 55% of annual electricity needs from rooftop solar.
The grid connection is often the slowest step. Start the DNO conversation early.
You do not always need capital. Power purchase agreements and energy-efficiency financing can put a system on the roof with little or no upfront spend.
Plan EV charging and solar together, so that daytime generation, depot charging and load management work as one system.
Table of Contents
Why warehouses suit solar
A typical distribution or logistics building has three things going for it. The roof is big and uncluttered compared with an office or a shop. Demand is steady through the working day, from lighting, conveyors, charging of materials-handling equipment, refrigeration and, increasingly, electric vehicles. And the owner or tenant usually pays commercial electricity rates, so every kilowatt-hour generated on site displaces a bought one.
That last point drives the economics. Solar earns most when you use the power yourself. Exporting surplus to the grid is worth less than avoiding an import, so the best-designed systems are sized around what the building consumes between about 8am and 6pm, not around how many panels physically fit.
How much of your demand can solar meet?
It varies by site, so treat published figures as examples, not promises. The UK Warehousing Association’s Solar Toolkit report describes a 50,000 sq ft Midlands warehouse whose rooftop solar supplied 55% of its annual electricity needs, with a 35% reduction in daytime electricity spend. That site used a zero-capital power purchase agreement and later added battery storage to capture excess generation and reduce peak-time grid costs.
What decides your own figure:
Usable roof area. Skylights, vents, smoke-extract units, walkways and fire setbacks all take space, so you rarely cover the whole roof.
Load profile. A site that runs one shift will use less of its own generation than a 24-hour operation or a cold store.
Orientation and pitch. Many warehouse roofs are shallow, and east-west layouts can suit a flat daytime demand curve well.
Efficiency of the panels. Roughly 90% of commercial rooftop installations use mono- or polycrystalline cells, and the BRE good practice guide puts monocrystalline efficiency at 15 to 20%, with some products reaching 23%. That guide dates from 2016, so current products are generally better, but the principle holds: higher efficiency matters most when roof space is the limit.
If you want a half-hourly picture, your supplier or a smart meter provider can usually supply the data. It is the single most useful input to any quote.
Is your roof suitable?
A good survey answers four questions before anyone talks about kilowatts.
Structure and roof material
The roof must carry the added load of panels, mounting and, on flat roofs, any ballast, as well as wind uplift and maintenance access. Newer buildings tend to have more spare capacity. Older sheds may need strengthening, and the original design calculations are not always to hand.
The covering matters as much as the frame. Roofs with an end-of-life covering, such as old fibre-cement sheets, are poor candidates for fixing panels on top. In those cases it usually makes sense to replace the roof and install solar as one project, so you only have one set of access costs and you reset the roof’s life to match the array. Ask any installer for a clear view of the remaining roof life and the warranty position before you sign.
Electrical capacity
The site’s main incomer, switchgear, distribution boards and protection settings all need review. Adding generation changes how current flows in the building, and an old board may need upgrading. This is also the point to think about the condition of what you already have. Thermal imaging surveys find loose connections and overloaded circuits that show up as heat, and what a hot spot on an electrical panel means is worth understanding before you tie new generation into a board that is already running warm.
Fire safety and insurance
Tell your insurer early. Warehouses holding high-value stock, and cold stores or food production sites where an outage would be costly, may face closer scrutiny on cable routing, isolators, firefighter access and the sprinkler layout. Getting the insurer’s view during design is far cheaper than redesigning after quotes.
Operating while it is installed
A live site cannot stop for a roof job. Good installers plan crane lifts, delivery windows and walkway exclusion zones around your goods-in and despatch times. The UKWA example describes an installation completed without interrupting operations, with the installer handling structural checks, planning and DNO notifications as part of the project.
Planning permission and grid connection
Planning
In England, rooftop solar on non-domestic buildings can often go ahead under permitted development (Class J), subject to conditions. These include restrictions on listed buildings, on roof slopes facing a highway in certain protected areas, and a 1MW capacity cap. Scotland, Wales and Northern Ireland have their own rules, and larger or protected-site schemes need a full application. Confirm with your local planning authority. If you are also adding charge points, our guide to EV charging planning permission for UK businesses covers the same questions for the car park and yard.
Connecting to the network
All generation connected to the distribution network needs the local Distribution Network Operator (DNO) to be involved. The Energy Networks Association’s connection guide explains that EREC G98 applies to smaller generation below 16A per phase, and G99 to larger projects. Most warehouse arrays fall under G99, which needs an application and, depending on the network, studies and possible reinforcement.
The same guide stresses that requirements are location-specific and that early, clear communication between developer and DNO is critical. In practice, that means:
Submit the application as soon as you have a credible system size, not after the contract is signed.
Ask whether export limitation could remove the need for network upgrades. A smaller export limit on a site that uses most of its power itself can speed things up.
Build the connection timeline into the programme. It is commonly the longest lead item, particularly on constrained networks and for larger systems.
What does it cost, and how can you pay for it?
We do not publish prices for solar, and any honest figure depends on roof, capacity and connection. Instead of quoting a number that could mislead, here is what shapes the cost of a project:
Factor | Effect on cost |
System size (kWp) | Larger arrays have a lower cost per kWp, but need more connection work |
Roof condition | Reinforcement or a re-roof can be a major added item |
Mounting type | Ballasted, clip-fixed and standing-seam systems differ in labour and materials |
Electrical upgrades | Switchgear, metering and protection changes |
Grid connection | DNO fees, studies and any network reinforcement |
Access and site constraints | Crane hire, working hours, safety exclusion zones |
Battery storage | Adds capital cost, but can raise self-consumption |
On payback, treat a single quoted “years to payback” with caution. It depends on your electricity tariff, how much you self-consume and what you are paid for exports. Ask for the model, with the assumptions behind it.
Ways to fund a system
Buy it outright. You keep all the savings and own the asset, but you fund the capital.
Power purchase agreement (PPA). A third party pays for and owns the system, and you buy the generated power at an agreed rate. The Midlands warehouse above used a zero-capital arrangement.
Energy-efficiency financing. Schemes of this kind let a business offset equipment costs against the energy savings, as in a 250kWp installation for a food business.
Lease or landlord-tenant arrangements. These are harder, because the landlord owns the roof and the tenant uses the power. The government’s UK Solar Roadmap names complex stakeholder interactions as a barrier and plans a standard contractual agreement for rooftop solar retrofits on leased commercial and industrial buildings. If you are a tenant, get the landlord’s consent and roof access terms agreed in writing first.
Compare options on what you pay per kWh over the whole term, the escalation clause, who is responsible for maintenance and what happens at the end of the contract or if you leave the building.
Choosing a solar partner
Whatever route you take, ask every provider the same questions:
Can you show a structural assessment and a roof-life opinion for my building?
Is the design based on my half-hourly data?
Who handles the DNO application, and what is the realistic timeline?
What are the panel, inverter and mounting warranties, and who services them?
How is performance monitored, and what is guaranteed?
Does the design allow for battery storage and EV charging later?
The last question is easy to forget, and it is where many sites save money.
When does battery storage make sense?
A battery stores midday surplus for use later, for instance in the late afternoon peak or an evening shift. It earns its keep where you export a lot of generation at low value, or where peak-time import is expensive. It is less compelling on a site that already uses nearly everything it generates. The Midlands example above added storage for exactly the first reason, to capture excess solar and cut peak-time grid costs.
Do the sums with your own load data. Reserving space and electrical capacity for a battery at the design stage is cheap. Retrofitting it into a layout that never allowed for it is not.
Solar and EV charging: one energy plan
If your warehouse runs vans, HGVs or company cars, or you want to offer charging to staff and visitors, solar and charging should be designed together. A depot that charges vehicles during the day can use rooftop generation directly. One that charges overnight needs storage or a different tariff strategy, and should be designed with that in mind.
Three practical points:
Capacity is shared. Solar generation, charge points and the building’s own load all sit behind the same connection. Smart load management lets you charge more vehicles without a costly supply upgrade. Our guides on smart charging for fleets and van fleet charging at the depot explain how.
Sequence the work. Doing the switchgear review, DNO application and cable routes once, for both solar and chargers, avoids paying for the same disruption twice.
Match the duty cycle. Vehicles that return at 5pm and leave at 6am need a different plan from those that sit on site all day. Our depot-first approach to fleet charging starts from the operation and works back to the hardware.
Our perspective
We install and manage commercial EV charging across the UK, and we see the same pattern on warehouse sites. The businesses that get the best result are not the ones that buy the biggest array or the most chargers. They are the ones that look at the whole site first: how much power the building really draws, what the connection can carry, and when vehicles are on site.
Solar is a strong partner to EV charging because daytime generation and daytime demand line up, and because smart charging software can steer charging toward the hours when the roof is producing. We would rather you size the solar to your load and use load management to avoid an expensive grid upgrade than install more capacity than the site can use.
For a warehouse owner or tenant, our advice is to start with data, check the roof and the electrics honestly, talk to the DNO early, and choose a funding model that matches how long you will occupy the building. Where it makes sense, we help commercial customers assess solar PV, battery storage and heat pumps alongside charging, so you get one joined-up plan.
— Swift Charging
Plan your charging and energy together
If solar is on your roadmap and electric vehicles are too, we can help you plan both. We design, supply, install and manage commercial charging for workplaces and depots, and we offer funded and charging-as-a-service options for businesses that prefer not to carry the capital cost. We can also help you look at solar, storage and heat pumps through our energy solutions for businesses, and at grant support where you are eligible.
The quickest first step is a commercial EV feasibility review of your site. For fleet sites, see our fleet EV charging solutions.
FAQ
Can any warehouse have solar panels?
Most can, but not all without work. The roof must carry the load, the covering must be in good enough condition to last the life of the array, and the electrical system needs capacity for the new generation. A structural and electrical survey settles it before you commit.
Do I need planning permission for solar on a warehouse roof?
In England, rooftop solar on non-domestic buildings is often permitted development under Class J, within limits such as a 1MW cap and restrictions for listed buildings and some protected areas. Other UK nations have different rules, so check with your local planning authority.
How long does a grid connection take?
It depends on the system size and your local network. Smaller systems under G98 are simpler, while G99 projects need an application to the DNO and can take months where the network is constrained. Apply early and ask whether limiting export could shorten the process.
Can I get solar without paying upfront?
Often, yes. A power purchase agreement means a third party funds and owns the system and you buy the electricity, and energy-efficiency financing can offset costs against savings. Check the tariff, the contract length and what happens if you leave the site.
Should I add batteries and EV chargers at the same time?
It is usually cheaper to plan for them together, even if you install them in phases. Doing the electrical review and grid application once, and reserving space and capacity, avoids paying for the same work twice.
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