What Does Agricultural Solar Cost per kW in 2026? (By System Size)

The single most useful number when budgeting a farm solar project is the cost per kilowatt (per kW), because it lets you compare quotes on a like-for-like basis regardless of array size. In 2026 a roof-mounted agricultural system on a typical UK farm building lands somewhere between £700 and £1,100 per kW installed, before tax relief. This guide breaks that figure down by system size, explains exactly what is and is not included, and shows what the payback looks like once you apply 100% Annual Investment Allowance.

The headline: £700-£1,100 per kW in 2026

For a standard roof-mounted system on a steel-frame agricultural building, the all-in 2026 price sits in the £700-£1,100 per kW band. Where you fall within that range is driven mostly by scale: a 50 kW system carries proportionally more fixed cost (scaffolding, design, DNO paperwork, mobilisation) than a 500 kW system, so the per-kW figure falls sharply as the array grows.

Two project types sit outside this band. Ground-mounted arrays usually run higher per kW because of groundworks, frames and cable trenching. Combined re-roof-plus-solar schemes carry the cost of the new roof on top — but spread across one set of scaffolding and one project, which is why we treat them separately in our combined re-roof plus solar guidance.

Cost per kW by system size

The table below shows indicative installed pricing for roof-mounted agricultural systems in 2026, before any tax relief. Figures are guide ranges, not quotes — every roof, half-board layout and grid connection is different.

System size	Cost per kW (installed)	Total project cost (guide)	Typical farm fit
50 kW	£950-£1,100	£48k-£55k	Single large barn, smaller dairy
100 kW	£850-£1,000	£85k-£100k	Grain store, mid-size dairy parlour
250 kW	£750-£900	£188k-£225k	Multi-building estate, poultry units
500 kW	£700-£850	£350k-£425k	Large mixed estate, intensive livestock
1 MW	£680-£800	£680k-£800k	Maximum permitted-development array

Note the 1 MW ceiling: under Class A of Part 14 of the GPDO 2015 (as amended in December 2023), rooftop solar on commercial and agricultural buildings is permitted development up to 1 MW. Above that you are into a full planning application, which adds time and professional fees. For the full money-page breakdown of agricultural solar panels cost by configuration, see our dedicated cost page.

What is included in the per-kW price

A credible per-kW quote from an MCS-certified installer should be turnkey and include:

• Panels — typically 440-590 W tier-1 monocrystalline modules.
• Inverters — string or hybrid inverters sized to the array.
• Mounting — roof rails, clamps and ballast appropriate to the roof type and wind zone.
• DC and AC cabling, isolators and protection.
• Scaffolding or fall-arrest access for the roof.
• Design, structural sign-off and MCS commissioning.
• DNO application — the G99 (or G98 for the smallest systems) grid-connection paperwork.
• Handover pack — certificates, monitoring setup and your MCS certificate (the document you need to claim the Smart Export Guarantee).

If a quote is materially below the £700/kW floor, check what has been stripped out — usually scaffolding, structural sign-off or the DNO application.

What is excluded — and the hidden costs that bite

The costs that derail farm budgets are almost always the ones outside the standard panel-and-inverter line. Watch for these three:

G99 grid-connection fees. Any system likely to export more than 3.68 kW per phase needs DNO approval under G99. The application itself is usually included, but if your local network is constrained the DNO may require grid-reinforcement works — occasionally tens of thousands of pounds. Always get the DNO position confirmed before signing.

Asbestos and re-roofing under CAR 2012. Many older farm buildings have asbestos-cement (often “Big Six”) roof sheets. You cannot simply screw mounting rails through them — disturbing asbestos is regulated under the Control of Asbestos Regulations 2012 and licensed removal is costly. If the roof needs replacing, a combined re-roof plus solar scheme is usually the most economic route because you pay for scaffolding once.

Three-phase upgrade. Larger arrays need a three-phase supply to export efficiently. If your building is single-phase, a DNO three-phase upgrade can add a meaningful four- to five-figure sum. Establish your existing supply early.

These are exactly the variables that move a project from the bottom to the top of the per-kW range, which is why a site survey beats any online estimate.

Financing your system

Most farms fund solar through one of three routes:

• Cash or AIA-backed purchase — the lowest lifetime cost and the only route that captures the full 100% AIA tax relief (see below). You own the asset and all the generation.
• Asset finance / hire purchase — spreads the capital over the savings, common for six-figure arrays. The farm still owns the asset and can claim capital allowances.
• Power Purchase Agreement (PPA) — a third party funds and owns the system, and you buy the electricity it generates at an agreed rate. Zero upfront cost but you forgo ownership and the AIA benefit. Our PPA for farms page explains where this stacks up.

Grant support is patchier than many expect, and the headline rates differ by nation. Our grants and funding page covers what is genuinely available in England, Wales, Scotland and Northern Ireland in 2026 — for most English farms the dominant tax lever is the AIA, not a grant.

Payback after 100% AIA

This is where farm solar economics get compelling. The Annual Investment Allowance lets a qualifying business deduct 100% of qualifying plant-and-machinery expenditure — including a solar PV system — against taxable profits in the year of purchase, up to a £1m cap. A 1 MW array at, say, £750k therefore sits comfortably within a single year’s AIA.

For a farm paying corporation tax at 25%, 100% AIA on a £100k system reduces the tax bill by roughly £25k in that year — effectively cutting the net cost of the system to around £75k. That single mechanism is the biggest lever on payback. Our 100% AIA for farm solar page works through the calculation in detail.

Combine the tax relief with the savings stack and typical paybacks land at four to six years, with these drivers:

• Avoided grid electricity at roughly 25-28p/kWh retail — every unit you self-consume on the farm is worth far more than one you export.
• Smart Export Guarantee income of around 8-15p/kWh on surplus units exported under your SEG tariff.
• Self-consumption ratio — farms with daytime loads (dairy parlours, grain dryers, cold stores) self-consume the most and pay back fastest. See our dairy parlours and grain stores sector guides for typical load profiles.

After payback, the system continues generating for its 25-year-plus design life, with the cheapest electricity a farm can buy.

How to get an accurate figure for your farm

Per-kW ranges are for budgeting; only a site survey produces a real number. The variables that matter most are roof condition and material (asbestos), your existing electrical supply (single- or three-phase), the DNO connection position, and your daytime load profile. A reputable agricultural solar panel installer will confirm all four before quoting, and will give you the cost-per-kW figure alongside the headline total so you can sanity-check it against this guide.

For the full configuration-by-configuration breakdown of what agricultural solar panels cost — roof-mounted, ground-mounted and combined re-roof — start with our money page, then book a survey.

Ready for a tailored figure for your buildings? Get a free agricultural solar quote.