How much do solar panels for barns cost?

What does barn solar actually cost?

There is no single price for solar panels on a barn, because a "barn" covers everything from a 6 kW roof on a converted threshing barn to a 500 kW array spread across a multi-shed poultry complex. What stays constant is the logic: the cost is driven by the size of the system in kilowatts (kW), and the price per kW falls steadily as the system gets bigger. A barn is one of the most cost-efficient places in the country to put solar precisely because its big, clear-span, unshaded roof lets you install at the cheaper end of the £/kW scale — you size to your electricity load rather than squeezing panels around dormers and chimneys.

This page sets out indicative pricing by system size and by barn type, what a quote should and shouldn't include, the real hidden costs that catch barn owners out, how the install is financed, and how payback is genuinely calculated. Every figure here is illustrative and aligned to the barn types we work on; a firm price always follows a roof survey and your half-hourly meter data.

Cost per kW by system size

The most useful way to think about barn solar cost is per kilowatt of installed capacity, because that number captures everything — panels, inverters, mounting, cabling, labour and commissioning — in one comparable figure. Three broad bands cover the barn market.

Small systems — under 30 kW (conversions, stables, traditional barns)

This is the domestic and small-outbuilding end: a converted barn that is now a home, a stable block, a tack room, a field barn or a traditional stone barn taking a modest array. Systems here typically run from 4 kW to around 30 kW. The cost per kW is highest in this band — roughly £900–£1,200/kW — because the fixed costs of a job (scaffolding, design, a DNO application, a day's mobilisation) are spread across fewer panels. A 6 kW barn-conversion roof and a 20 kW smallholding system both sit here.

Mid-size systems — 50 to 250 kW (working barns)

This is the heart of the working-barn market: steel-frame portal sheds, livestock and cattle buildings, mid-sized stores. Here economies of scale kick in and the cost per kW drops to around £750–£950/kW. The same crew, the same design effort and the same single grid application now cover three to ten times the capacity, so each kW gets cheaper. A 100 kW system on a portal barn or a 150 kW livestock-building array lands in this band.

Large systems — 300 to 500 kW (grain stores, poultry and pig units)

The biggest barn roofs — grain and potato stores, multi-shed poultry and pig complexes — carry the largest arrays, from 300 kW up to 500 kW (and beyond on multi-building sites). This is the cheapest band per kW, roughly £700–£850/kW, because the install is essentially industrial in scale: bulk panel pricing, commercial-grade string inverters, and a fixed-cost grid connection amortised across a very large system. These projects have the lowest unit cost and, on the right load profile, the fastest payback.

Indicative £/kW by system size

System size	Typical barn types	Indicative cost per kW	Typical total project value
Under 30 kW	Barn conversions, stables, traditional & listed barns	£900–£1,200/kW	£6,000–£40,000
50–250 kW	Steel-frame portal barns, livestock & cattle buildings	£750–£950/kW	£40,000–£185,000
300–500 kW	Grain stores, crop barns, poultry & pig units	£700–£850/kW	£180,000–£450,000

These ranges assume a sound, modern roof that can take panels directly. The variables that move you within a band — and the costs that sit outside the panels themselves — are covered below.

Cost by barn type

Because barn solar is sized to roof and load rather than farm acreage, the price band tracks the building type closely. Here is where each of the six barn types we cover typically lands.

• Steel-frame portal barns — the modern agricultural standard. Systems run roughly 30–300 kW, with typical project values of £24,000–£270,000. The clear-span low-pitch roof is the single best canvas for rooftop PV, and the engineered frame usually carries the modest added load with a simple structural sign-off, keeping costs predictable.
• Grain stores & crop barns — among the largest single roofs on any farm, hosting 50–500 kW arrays at typical values of £40,000–£450,000. The roof is cheap to cover per kW; the design cost is the seasonal autumn drying load, which decides whether you add a battery, design for export, or size to baseload only.
• Livestock & cattle barns — cattle courts, cubicle housing and sheep sheds at 20–200 kW, typically £18,000–£185,000. Dairy units with milk cooling and parlour loads achieve exceptional self-consumption, which improves the return without changing the build cost much.
• Poultry & pig units — the strongest economics of any barn type, with 50–500 kW arrays at £40,000–£450,000. A near-constant 24/7 baseload means most generation is used on site, so although the capital cost matches a grain store, the payback is the fastest in the sector.
• Traditional & listed barns — stone, brick and timber-framed barns taking smaller, sensitively-designed systems of 6–40 kW at typical values of £7,000–£40,000. Heritage design (discreet siting, all-black in-plane panels) and the consenting route add to the unit cost, which is why this band sits at the higher £/kW end.
• Barn conversions & smallholdings — converted dwellings, annexes and stables at 4–20 kW, typically £6,000–£22,000. A domestic install on a barn-sized roof, often feeding a heat pump, EV charger and home battery, and eligible for the residential 0% VAT rate.

What's included in a barn solar price

A properly scoped barn quote should be turnkey. At a minimum it includes:

• The panels — the modules themselves, sized to your roof and load.
• Inverter(s) — string inverters for most barns, sized to the array, with monitoring.
• Mounting and fixings — the rail system clamped to your box-profile or fibre-cement sheeting, engineered for the building's wind and snow loading.
• DC and AC cabling, isolators and protection — the full electrical run from roof to consumer unit or distribution board.
• Design, structural sign-off and the G99 grid application — the engineering and paperwork that make the system compliant and connectable.
• Installation labour, commissioning and handover — including MCS certification where applicable, which is the gateway to Smart Export Guarantee income and most warranties.

On a working barn, that turnkey figure is what the per-kW bands above describe. The costs that push a project up — and that an honest quote separates out as line items rather than burying — are the barn-specific ones below.

The real hidden costs of barn solar

Barns carry cost risks a house roof never does. A reputable survey finds these before you sign, not after. The big ones:

Structural appraisal

Every barn install starts with a short structural appraisal to confirm the purlins and frame can carry the added PV dead load (around 10–15 kg/m²) plus wind uplift. Modern steel portal frames almost always pass; older or modified barns occasionally need minor strengthening, which is designed in before any panels go up. The appraisal itself is a modest, fixed cost — but skipping it is how barns get damaged.

Asbestos strip-and-reclad

This is the single biggest swing factor. Asbestos cement is very common on barns built before 2000, and it cannot be drilled or loaded with panels — only a licensed contractor may remove it under CAR 2012. Where it's present, the proven route is a combined strip-and-reclad to modern profiled steel, then PV on the new roof. It adds real cost, but the solar business case often part-funds a re-roof you were going to need anyway, solving a deferred maintenance liability and an energy upgrade in one project.

Scaffolding and access

Tall, wide barn roofs need proper access. Scaffolding, edge protection and sometimes a mobile elevating work platform are priced per project and scale with roof height and area. A low eaves-height cattle shed is cheap to access; a tall grain store is not.

DNO and G99 connection

Any system above 3.68 kW per phase — which is almost every barn — needs a G99 application to the local network operator. Rural networks are frequently capacity-constrained, and a connection study, an export limiter, or a no-export design is often the route to a faster, cheaper connection. The application and any required works are a distinct cost, and on tight rural networks the timeline (not the price) is usually the constraint.

Export limiter or battery

Where the grid won't accept full export, you either fit an export limiter (cheap, but you forgo some surplus income) or add battery storage (more capital, but you capture evening and seasonal load). On a 24/7 baseload barn a battery is often optional; on a grain store's seasonal peak or a barn-conversion home it frequently earns its place. We size storage only where the numbers justify it.

How barn solar is financed

Few barn owners pay cash for a large array, and several routes make the numbers work harder.

Capital purchase with 100% AIA (working barns)

The strongest option for any trading farm, estate or rural business. Solar PV qualifies as plant and machinery for the 100% Annual Investment Allowance, so the whole installed cost is written off against taxable profit in year one (up to the £1m AIA cap, which almost every barn install sits comfortably within). For a limited company that's up to roughly a 25% effective tax saving in year one; sole-trader and partnership farms get comparable relief. This does not apply to a purely residential barn conversion.

Asset finance

Where you'd rather not deploy capital, asset finance or a commercial loan spreads the cost over the system's life. Structured well, the monthly repayment is offset by the energy saving from day one, so the array can be broadly cash-flow neutral or positive while you still own it outright at the end.

Power Purchase Agreement (PPA)

On larger sites with a strong, steady load, a PPA can put the panels on your roof at no upfront cost: a funder owns the system and you buy the power it generates at a fixed rate below grid price. It removes the capital outlay (and the AIA benefit), and suits operators who want certainty without ownership. It only stacks up where self-consumption is high — poultry, dairy and large stores being the obvious candidates.

0% VAT on residential conversions

If the barn is a dwelling — a converted barn that someone lives in — solar PV qualifies for the 0% VAT rate on energy-saving materials in Great Britain until 31 March 2027, after which it returns to 5%. On a £15,000 conversion install that's a £3,000 saving versus the standard rate. This is a residential relief; it does not apply to a commercial agricultural barn.

How payback is calculated

Two numbers matter, and they answer different questions.

Simple payback is the headline: total installed cost divided by annual financial benefit (energy saved plus any export income). It tells you how many years until the system has paid for itself. It's easy to grasp but ignores the time value of money and the system's full 30-year life.

Internal Rate of Return (IRR) is the investor's number: it expresses the array as an annual percentage return across its whole lifetime, accounting for rising electricity prices, panel degradation (typically under 0.5% a year) and the tax position. A barn solar IRR comfortably in double digits is common, which is why a barn roof is increasingly treated as a 30-year income asset rather than a cost.

The single biggest lever on payback is self-consumption — the share of generation you use on site instead of exporting. Every kWh you consume avoids the full grid import price; every kWh you export earns only the lower SEG rate. That's why barn type matters so much to the return.

A worked example

Consider an illustrative 180 kW array on a broiler-shed complex — a typical poultry install on two large, near-south-facing steel roofs. At a representative cost in the large-system band, the project comes in around £150,000 before tax relief. With continuous ventilation, heating and lighting running 24/7, self-consumption sits near 88%, so almost all of the roughly 165,000 kWh generated each year is used on site at full import price. The annual benefit lands around £38,000. Simple payback is therefore about 4.4 years — and that's before the 100% AIA writes the cost off against tax in year one, which sharpens the after-tax return further. By contrast, an illustrative 12 kW system on a converted barn home, with a 10 kWh battery and an annual benefit near £1,650, pays back over roughly 8.5 years — slower, but still comfortably inside the system's lifespan and helped by the 0% VAT rate. Both are scenarios, not specific customers; your figures follow your roof, your load and your meter data.

What makes a barn cheap — or expensive — to do

Two barns of identical size can differ by tens of thousands of pounds. The factors that make a barn cheap to solar:

• A sound, modern profiled-steel or fibre-cement roof that takes panels directly — no re-roof needed.
• A large, clear-span, low-pitch roof facing close to south with no shading.
• An engineered steel portal frame that passes structural appraisal without strengthening.
• A high, steady on-site load (poultry, dairy, drying) that lifts self-consumption and shortens payback.
• Low eaves height and easy ground access, keeping scaffolding modest.
• Spare grid export capacity, so no costly connection study or export-limiting workaround.

The factors that make a barn expensive:

• An asbestos-cement roof requiring licensed strip-and-reclad before any PV.
• A fragile, old or under-engineered roof needing structural strengthening.
• Listed status or a conservation-area location, requiring heritage design and consent.
• A tall roof or awkward access driving up scaffolding cost.
• A constrained rural grid needing a connection study, export limiter or battery.
• A low or purely seasonal load — like a grain store's autumn peak — that pushes you toward storage or an export-led design to capture value.

The practical takeaway: the building decides the price as much as the panels do. A modern poultry or portal barn with a clean roof and a real load is about as cost-effective as solar gets in the UK. A listed stone barn or an asbestos-roofed store needs more work — but with the right design and the re-roof or heritage cost factored in honestly from the start, almost every barn roof can be made to pay.

For sizing and cost detail by building type, see the steel-frame portal barn, grain store and poultry and pig unit pages, or read how the tax and export schemes stack up on our grants and funding guide. When you're ready for a firm figure, a free desk feasibility from your meter data is the fastest way to a real number.