Dairy Farms: Solar panels for agriculture

Dairy: the agricultural enterprise where solar pays back first

When farmers ask where solar panels for agriculture make the strongest case, dairy is almost always the first answer. The reason is simple: a dairy enterprise consumes electricity around the clock. Bulk tank cooling, the milking parlour, vacuum and milk pumps, water heating, plate coolers and yard lighting all draw power day and night, so the units your panels generate are used on the holding rather than exported at a lower rate. Self-consumption is the single biggest driver of solar economics across all of agriculture, and how much a dairy uses depends on sizing: an array sized to the daytime cooling and parlour load uses most of its output, while one sized to annual consumption exports much more. An Irish Teagasc model (July 2025) of a 100-cow farm with an array sized to annual use consumed only 27% of its output on site (41% with a battery); there is no published UK figure. Sized to the daytime load, an indicative simple payback is roughly 4 to 7 years; sized to annual use it is nearer 10 years. Every unit used on site displaces imported grid power, which costs a business far more than the export rate it would otherwise earn.

Energy is one of the few costs on a dairy holding you can act on directly, and solar lets you fix part of it for the life of the system with a single capital decision. A dairy farmer takes the milk price the processor offers; very little about the income side is within your control. Solar flips one of the few cost levers you genuinely hold, and it does so while feeding the sustainability and carbon reporting that milk buyers and farm assurance schemes increasingly require. Schemes such as Red Tractor and Arla 360 reward demonstrable progress on emissions, and a live solar array is auditable evidence rather than a promise. Looked at as part of a wider agricultural energy strategy rather than a one-off purchase, a dairy array protects margin in a sector where margin is permanently under pressure, and it does so for the full life of the system.

What a typical system looks like and how it should be sized

A dairy system typically sits in the 30 to 250 kW range, which is roughly 55 to 460 panels spread across about 200 to 1,500 square metres of parlour, collecting yard and youngstock shed roof. A system of that size generates in the region of 24,000 to 250,000 kWh each year (800 to 1,000 kWh per kW installed) and avoids roughly 3 to 33 tonnes of CO2e annually at the 2026 UK grid factor of 0.131 kg per kWh. A good installer will not simply fill the roof to its edges. Sizing should come from your half-hourly meter data and the genuine shape of your milking day, because a robotic herd that milks continuously presents a very different load curve to a twice-a-day parlour with two clear demand peaks. Where cooling and water heating dominate, the system should be sized firmly for self-consumption, and the installer should model the heat recovery and pre-heating loads that line up neatly with daytime generation. The aim is a system the dairy actually absorbs, not the largest array the roof could physically hold.

The shape of the load matters as much as its size. A robotic parlour spreads demand evenly through the day and night, which suits a steady solar profile; a conventional parlour concentrates demand around the morning and afternoon milkings, which can mean either a slightly smaller array or the addition of a battery to carry midday generation into those peaks. It is also worth asking the installer whether water heating and pre-cooling can be shifted to run when the sun is up, because every kilowatt-hour moved into daylight hours is a kilowatt-hour you no longer import. None of this should be guesswork: it should come straight out of your consumption data, so ask the installer to share the model and show exactly how the system was sized and why.

Costs, payback and tax relief

A dairy project typically lands between £30,000 and £240,000 ex VAT depending on herd size and available roof (indicative, from the DESNZ May 2026 median of £1,204 per kW for 10-50 kW systems and installer and industry price guides above 50 kW, excluding grid reinforcement, re-roofing and batteries). The indicative simple payback is roughly 4 to 7 years where the array is sized to the daytime load and most output is used on site (assuming 24-28p avoided import), or nearer 10 years if it is sized to annual use and exports more; after that the system keeps generating, with 25 to 30 year module performance warranties and around 0.5% output loss a year. The biggest financial lever in agricultural solar is tax. Solar PV qualifies as plant and machinery, so the 100% Annual Investment Allowance lets most farm businesses relieve the full cost against profit in the first year, up to 1 million pounds a year, worth up to around a quarter of the project value back as tax saved for a limited company and comparable for partnership or sole-trader structures. Most dairy installs fall well within the allowance cap and are relieved in full in year one under the AIA. The Smart Export Guarantee pays for any surplus you do export, and our cost guide sets out worked numbers across different herd sizes, while the funding page explains the tax and export side in full.

It is worth being clear about why dairy payback is so strong relative to other parts of agriculture. The return on any solar system is driven by how much of the generation you use yourself, because self-consumed units are valued at the price you would otherwise pay to import, while exported units earn the lower Smart Export Guarantee rate. A dairy whose array is sized to its daytime cooling and pumping load uses most of what it makes, so the avoided-import value is high and steady; size it to annual consumption and far more is exported. Combined with the year-one tax relief, that is what places a dairy install among the fastest-payback agricultural solar projects. This guide presents the numbers as a range rather than a single headline, and a good installer should do the same, because herd size, tariff, roof orientation and whether you add storage all move the figure.

Funding routes in detail

The universal route for every dairy business is the 100% Annual Investment Allowance, which applies whether you trade as a company, a partnership or a sole trader, and which gives full relief in year one on up to 1 million pounds of qualifying spend a year, comfortably above a typical dairy project. Solar PV is special-rate plant and does not qualify for full expensing. Beyond that, the Smart Export Guarantee provides ongoing income on exported units for systems up to 5 MW, with MCS certification required for systems up to 50 kW and Ofgem ROO-FIT accreditation used for larger ones, and export rates for businesses vary roughly from 3 to 15p per kWh depending on the supplier tariff. There is no farm solar capital grant open in England in 2026: the Improving Farm Productivity round that funded rooftop solar closed in July 2025, and FETF 2026 did not fund solar panels. The Sustainable Farming Incentive does not pay for solar panels (it reopened as SFI26 in 2026, paying for land-management actions only), though land under panels can sometimes sit alongside separate environmental actions, subject to scheme rules, so check with the RPA. Dairy farms in Wales, Scotland and Northern Ireland should check current devolved schemes, none of which pays for solar panels at the time of writing. Ask your accountant to confirm the tax position before you commit.

Compliance and sector considerations

Rooftop PV does not affect food hygiene compliance under Regulation 853/2004, nor does it disturb your parlour electrical certification, but the install itself needs careful planning around a live working dairy. Ask the installer how they will manage slurry pit and silage clamp electrical safety during the work, and agree a schedule that works around calving rather than straight through it. Rooftop PV on agricultural buildings in England is generally permitted development with no capacity cap, with prior approval needed over 50 kW, while listed farm buildings need Listed Building Consent, and a G99 grid application is needed for anything above 16 A per phase, which covers almost every farm system. A common blocker across agriculture is the roof itself: many pre-2000 farm buildings carry asbestos cement sheeting, which panels should not be fixed to. Under the Control of Asbestos Regulations 2012 most asbestos-cement sheet removal is non-licensed work, but it must be done by trained, competent contractors following HSE guidance. The usual answer is a strip and reclad to profiled steel with PV on the new roof, and the solar business case can help fund a re-roof that had been deferred for years. Where the holding is tenanted, landlord consent is required for the structural alteration, and most institutional landlords operate standard tenant solar agreements.

What a good installer should do on this kind of project

A good installer's process should remove the uncertainty that puts farmers off. Ask them to start with your half-hourly meter data so the system is sized to real consumption and the genuine milking pattern, not an optimistic guess. A structural survey and an asbestos check on every roof should come before the quote, so the price in the written proposal is the price you pay, with no surprises uncovered on the day of the install. The G99 grid application should go in early, alongside the survey, because on rural networks the connection is usually the longest part of the timeline and you want the distribution operator's clock running as soon as possible. Where export capacity is constrained, ask about a design for self-consumption only, a smaller no-export system that can cut the connection timeline sharply on a capacity-limited network. Check what workmanship warranty is offered and whether it is insurance-backed, and agree how the work will fit around your stocking and seasonal calendar so the dairy keeps running throughout. The final grid connection is usually the only real interruption, and it should be scheduled for a quiet window. Send the enquiry form and SEO Dons passes it to an installer covering your area, who then reviews your meter data, surveys the buildings and quotes.

An illustrative example

As an illustrative example, not a real farm or project: consider a 220-cow farm with a robotic parlour and bulk tank cooling, paying around 45,000 pounds a year for power. It installs roughly 118 kW across the parlour and youngstock shed roofs, about 218 panels generating in the region of 106,000 kWh a year (900 kWh per kW) and avoiding about 14 tonnes of CO2e. At an indicative 900 pounds per kW the cost would be about 106,000 pounds ex VAT. If the array is sized to the daytime cooling load and 75% of output is used on site (an assumption, not a measured figure), at roughly 26p avoided import and 4p export the saving would be around 21,800 pounds a year, a simple payback close to 5 years; sized to annual use with far more exported, it would be nearer 10 years. The full cost could be relieved in year one under the Annual Investment Allowance. The figures here are illustrative and depend on your herd, tariff and roof; ask the installer to model your own numbers from your meter data before anything is committed, and never treat a worked example as a guaranteed outcome for a different farm.

If your holding mixes dairy with cropping or grazing, our pages on solar for arable farms and livestock units may also apply. To see the economics, read the cost guide and the grants and funding page, then request a free quote from your meter data, or read the agricultural solar FAQs first.