The comparison in 2026
Most UK farm buildings have ridge orientations that produce either south-facing roof slopes (ideal for PV) or east-west-facing slopes (alternative orientation with different daily generation profile). The choice affects daily generation curve and self-consumption.
Detailed comparison
South-facing economics. Annual generation: approximately 950 kWh/kW for UK latitude at 30° tilt. Daily curve: peaks at midday with a steep curve. Self-consumption at typical farm: 65-90% depending on load profile. East-west economics. Annual generation: approximately 850 kWh/kW (10% below south-facing). Daily curve: morning peak on east face, afternoon peak on west face — flatter overall daily curve. Self-consumption at typical farm: 75-95% depending on load profile. Net economic comparison. For a 200 kW install: south-facing generates 190,000 kWh/year; east-west generates 170,000 kWh/year. Difference of 20,000 kWh/year. But: east-west self-consumption is typically 5-10% higher than south-facing equivalent. For a dairy parlour with continuous baseload, south-facing might achieve 85% SC vs east-west 92% SC. Net effective economic generation: south = 161,500 kWh self-consumed; east-west = 156,400 kWh self-consumed. The gap closes substantially. When south wins. Single-orientation roof with strong daytime load profile. Buildings where annual generation maximisation matters most. Installations where SEG export is a key income stream. When east-west wins. Building with strong daytime baseload (dairy parlour, intensive livestock) — flatter daily curve aligns with continuous load. Installations on capacity-constrained feeders where lower peak export matters. Buildings naturally oriented east-west due to ridge alignment. No-decision case. Most UK farm buildings have their orientation already determined by the building's existing ridge line. You install on whichever slope is available. Recommendation. For most UK farm installs, work with the existing roof orientation rather than trying to alter it. The economic differential between south and east-west is moderate; the differential between installing PV and not installing is enormous.
How to decide for your specific install
The right choice depends on the specifics of your farm: roof geometry; load profile; capital sensitivity; future expansion plans; long-term operational priorities. We model multiple specification scenarios in every feasibility study where the choice is material. Send us your half-hourly meter data and building dimensions — we deliver a free desk feasibility within 7 working days, including specification recommendations with clear rationale.
Common questions
What do you typically recommend?
Depends on the specifics of the site. Our default approach is documented in the comparison above; we model alternative scenarios where the project requirements suggest different specification choices.
How material is the difference in practice?
Most specification differences sit at the margin of project economics — typically 2-10% impact on overall 25-year NPV. The fundamental decision (whether to install PV at all) is far more material than the specification choice within PV.
Can we change specification later?
Some changes possible without complete reinstall (e.g., battery brand, inverter replacement at end of life). Other choices (e.g., optimised tilt vs roof-pitch following) are baked in at install. Specification decisions for permanent elements should be made carefully at design stage.
Do you have a preferred manufacturer or product?
We're independent of any specific manufacturer. Every quote includes specification recommendations specific to the site geometry, the farm's strategic priorities, and current market pricing. We never push a specific brand without rationale.