Ground-Mounted vs Rooftop Solar for Farms

Farms are unusual in UK commercial solar because they almost always have two viable places to put panels: the large, simple roofs over barns, grain stores, parlours and livestock sheds, and the land itself. Most sectors only choose a funding route. A farm chooses a whole site type first, and that decision shapes the cost, the planning path, the grid application and the income model. This guide compares ground-mounted and rooftop solar panels for agriculture on the terms that actually decide it for a working farm.

The two options in plain terms

Rooftop solar. Panels go on existing farm buildings: machinery sheds, grain stores, dairy parlours, poultry and pig units, glasshouses. You use roof space you already own, so no land comes out of production and, within size limits, usually no planning application is needed. The trade is that you are capped by the roof area and orientation you have, and older buildings may need work before they can carry panels.

Ground-mounted solar. Panels sit on frames in a field, typically on marginal or underused land. You can build far larger than any single roof allows, angle every panel optimally, and on the right land run sheep underneath or stack biodiversity actions on top. The trade is that ground-mount almost always needs full planning permission and takes land out of cropping.

The two are not mutually exclusive. On many holdings the right answer is rooftop on the buildings plus a ground-mount lease on the poor pasture, and we model both together rather than treating them as rivals.

The two routes head to head

The trade-offs line up fairly cleanly across the two site types:

Factor	Rooftop	Ground-mounted
Typical cost per kW	Around £750 to £1,000 per kW above 100 kW	Around £600 to £800 per kW above 500 kW
Typical system size	20 kW to 500 kW	500 kW to 10 MW and beyond
Land taken from production	None	Yes, unless agrivoltaic dual use
Planning	Permitted development within size limits on agricultural buildings	Full planning permission in almost all cases
Grid connection	G99 above 17 kW per phase	G99, often a larger and slower connection
Self-consumption	Usually high, sits over the load	Often lower, more is exported
Roof condition risk	Asbestos or weak roofs may need work first	Not applicable
Best for	Most farms, fastest payback	Marginal land, large schemes, lease income

The headline trade is scale and siting freedom versus simplicity and self-consumption. Ground-mount gives you almost unlimited size, optimal panel angle and a lower cost per kilowatt at scale, but it costs you land, a planning application and usually a bigger grid job. Rooftop gives you a fast, low-friction install that sits directly over your load and pays back quickly, but you take the roof you have and live within its limits.

When rooftop wins

Rooftop is the default for most farms, and for good reasons.

The first is self-consumption, the single biggest driver of return in farm solar. Every unit you use on site displaces a unit you would otherwise buy at full retail price, while every exported unit earns only the lower Smart Export Guarantee rate. Rooftop panels sit directly over the load, so an enterprise with steady daytime or round-the-clock demand keeps most of what it generates. A dairy is the clearest case: milk cooling, parlour pumps and lighting run 24/7, self-consumption is often 90% or higher, and payback lands around five to six years. Poultry and pig units with high year-round ventilation loads behave similarly. For these holdings, rooftop is not just easier, it is the better economic answer.

The second is planning and speed. Rooftop PV on agricultural buildings generally falls under permitted development within the size limits in the General Permitted Development Order, so most installs avoid a full planning application, removing months of timeline and a layer of cost and risk.

The third is land. If your ground is productive, taking it out of cropping rarely makes sense when idle steel roofs sit over the same business.

Rooftop wins when you have suitable buildings, a decent year-round load, and roofs in sound condition or worth re-roofing anyway.

When ground-mount wins

Ground-mount comes into its own in a narrower but important set of cases.

The clearest is underused marginal land. A field that crops poorly, a corner that floods, rough pasture that yields little, these are where ground-mount shines, because the opportunity cost is low and the array can be sized to suit. This is also the basis of the lease model: a developer leases the land, typically at around £900 to £1,300 per acre per year on a 25 to 40 year term, well above the arable rental poor ground would otherwise command. The developer carries all the capital and operational risk, and on suitable sites the land keeps grazing sheep.

The second is scale. If your electrical load or income ambition is larger than your roofs can serve, ground-mount is the only way to get there. Arable holdings with seasonal grain-drying peaks, or estates pursuing a multi-megawatt scheme, cannot fit that capacity on building roofs.

The third is roof constraints. Where farm buildings carry asbestos cement sheeting, or spans too weak to take panels, the rooftop route needs a strip-and-reclad first. Where that re-roof is not worth doing on its own merits, ground-mount sidesteps the roof question entirely.

Ground-mount wins when you have land you can spare, a need for more capacity than your roofs allow, or roofs that are not solar-ready.

Planning and land-use considerations for farms

This is where the two routes diverge most sharply. Rooftop PV on agricultural buildings is usually permitted development, subject to the size limits in the GPDO; listed farm buildings are the exception and need Listed Building Consent. Beyond that, the planning path is light.

Ground-mount is a different matter. Small ground arrays up to roughly 9 metres by 9 metres by 4 metres in height can fall under permitted development, but anything of commercial scale sits well above that and needs full planning permission. Schemes above 5 MW additionally require an Environmental Impact Assessment. Planners weigh the loss of agricultural land, visual impact, and increasingly biodiversity, so the quality of the land matters: a scheme on genuinely marginal ground with a dual-use or grazing plan is far easier to consent than one on prime arable. Agrivoltaic designs, where panels sit above grazing or sheltering crops and the land stays in agricultural use, strengthen the planning case considerably and can let Sustainable Farming Incentive biodiversity actions stack on the same acres. You can read the scheme detail on the Sustainable Farming Incentive pages at GOV.UK.

Grid connection shapes both routes but bites harder on ground-mount. A G99 application is required above 17 kW per phase, and rural networks are frequently capacity-constrained. A large ground array needs a larger export connection that, on a congested network, can take many months to secure. Where export capacity is the bottleneck, a rooftop system sized for self-consumption only, with no export, can be commissioned far faster, one more reason rooftop tends to be the quicker win.

If you rent the land or buildings, any structural alteration or change of land use needs landlord consent on both routes. Most institutional rural landlords run standard tenant agreements, so this is friction to plan for rather than a barrier.

A worked example

To see how this plays out, take an illustrative case, a composite based on typical UK projects and not a named client. Imagine a mixed family farm with a 180-cow dairy and around 12 acres of marginal pasture that crops poorly. The parlour and youngstock shed roofs carry roughly a 120 kW rooftop system of around 220 panels, generating about 108,000 kWh a year. Because milk cooling runs around the clock, self-consumption sits near 90%, almost every unit displaces grid electricity at full price, and with full first-year tax relief the rooftop payback lands close to five years. That system is permitted development, sits over the load, and takes no land.

Ground-mount could not be justified on the productive fields, but the 12 acres of poor pasture is a different question. Rather than buy an array, the farm leases it to a UK developer for a roughly 1.8 MW scheme generating about 1.7 million kWh a year, on a 25-year lease at around £1,200 per acre per year. The land keeps grazing sheep, biodiversity actions stack with the lease income, and the developer carries all the capital and grid risk. The farm uses both site types for different jobs: rooftop for cheap self-consumed power on the buildings, a ground-mount lease for reliable income on land that earned little. The figures are illustrative and depend entirely on your roofs, your land, your load profile and the developer terms in your region.

How to choose

The decision tree is short. If you have suitable building roofs, a steady year-round load and sound or re-roofable buildings, start with rooftop, it pays back fastest, needs no planning and takes no land. If you have underused marginal land, need more capacity than your roofs can hold, or your roofs are not solar-ready, consider ground-mount, owned or as a developer lease. On many farms the answer is both.

The right answer is specific to your buildings, your land and your load, so the sensible next step is to model both against your real meter data. Our cost guide sets out the underlying numbers, the grants and funding page covers the AIA, SEG and lease economics for each route, and the savings calculator gives an instant indicative figure. If you are still weighing whether solar suits your holding at all, our is solar worth it for farms guide works through the deciding factors. When you are ready, request a free feasibility and we will model rooftop against ground-mount for your specific farm.