Lincolnshire arable farm, 280 acres · 145kWp combined
145 kWp (split across grain store + Dutch barn) commercial solar PV installation with combined grant + tax relief stack delivering 1.2 years post-tax payback on £128,000 gross capex.
Anonymised composite case study
Names, dates and exact financial figures have been changed to preserve client confidentiality. Project structure, funding combinations, technical configuration, and order-of-magnitude figures are real and based on completed work. Full editorial disclosure on the about page.
Project snapshot
| Sector | Mixed arable farm · grain drying + cold storage |
| Location | Lincolnshire (East Midlands) |
| System size | 145 kWp (split across grain store + Dutch barn) |
| Battery storage | 100 kWh |
| Gross project capex | £128,000 |
| Grant value | £32,500 (FETF) |
| Year-1 tax relief | £43,200 (AIA at 45% IT) |
| Net effective cost | £52,300 |
| Annual savings/revenue | £43,200/year |
| Post-tax payback | 1.2 years |
| CO2 saving | 47 tCO2e/year |
| Year commissioned | 2025 |
Context
The farm is a family partnership operating 280 acres of mixed arable across Lincolnshire — wheat, oilseed rape, sugar beet. Three principal buildings: grain store (1,400 m² roof), Dutch barn used for machinery storage (600 m²), and concrete-pad cold storage for potato seed (300 m²). Annual electricity import: 142,000 kWh — driven primarily by grain drying (August-October peak) and cold storage refrigeration year-round.
The partnership has two partners: the father (semi-retired, higher-rate income tax) and the son (managing partner, basic-rate income tax). Net 2024 partnership profit £180,000. The farm has historically pursued diversification — a B&B operation in a converted farmhouse outbuilding generates ~£35k/year additional revenue.
The challenge
Two specific constraints shaped the approach:
1. **Three-phase electrical service.** The farm had only single-phase supply to the grain store building. Three-phase upgrade was required for systems above 17kWp — added cost £22,000 (DNO connection fee plus internal switchgear). 2. **Asbestos cement roofing on Dutch barn.** The 1970s-built Dutch barn roof was ACS — required replacement before solar. Cost £18,000 (replaced with modern composite sheet plus integrated solar mounting).
The site's electrical load profile was unusually strong: - August-October: grain drying peak load 35-45 kWp - Year-round: cold storage refrigeration 8-12 kWp constant - Diurnal: ventilation and lighting 4-8 kWp - Combined daytime peak: 55 kWp average
Funding approach
Funding stack:
1. **Farming Equipment and Technology Fund (FETF) 2024.** The farm successfully applied under code 12 (refrigerated grain handling and storage). FETF awarded £32,500 — 40% of the eligible portion of capex (cold-store specific elements). 2. **Annual Investment Allowance (AIA).** As a partnership, AIA applies at each partner's marginal income tax rate. Father at 45% IT rate: £56,250 of AIA allocation saving £25,313. Son at 40% IT rate: £39,750 of AIA saving £15,900. Combined AIA tax saving: £41,213. Plus Class 4 NI savings of £1,987. Total tax relief: £43,200. 3. **Smart Export Guarantee.** Octopus Outgoing Fixed at 15p/kWh on the 30-35% of generation exported (mostly outside drying season). 4. **Battery storage** sized for evening cold-store demand smoothing (100 kWh — lower-quality 280Ah LFP cells, £35,000 fully installed). 5. **No farm-specific finance** — the farm funded the £52,300 net cost from operating cashflow.
Project breakdown: - Solar PV (145 kWp): £108,750 - Battery storage (100 kWh): £35,000 - Three-phase upgrade: £22,000 - ACS roof replacement: £18,000 - DNO G99 application + commissioning: £6,400 - **Gross capex: £190,150** - Less FETF grant: £32,500 - Less AIA tax saving: £43,200 - Less SEG income year 1: £6,800 - **Net first-year cost: £107,650**
Outcome & performance
The system commissioned in May 2025. Year-one performance (May 2025 - April 2026):
- Total generation: 138,500 kWh - Self-consumption: 70% (97,000 kWh) - Export: 30% (41,500 kWh) — SEG income £6,225 at 15p/kWh - Saved electricity import: 97,000 × 31p = £30,070 - **Combined savings/revenue year 1: £36,295**
Year 1 payback maths: - Net cost £107,650 / annual saving £36,295 = 3.0 years for cash payback - Inclusive of tax relief and grant on £190k gross capex, post-tax payback: 1.2 years
The farm now consumes 70% of generation on-site and is preparing a follow-on 250 kWp ground-mount installation on a 1.5-acre marginal field for the 2027-28 financial year. Cash flow now supports re-investment in additional drying capacity.
Lessons learned
- FETF codes are narrow — solar PV qualifies only when combined with productive farming equipment (cold storage, grain drying, refrigeration).
- Partnership AIA scales with partner income tax rates — higher-rate partners save more. Plan asset purchases for the tax year that maximises relief.
- Three-phase upgrade is the single biggest hidden cost on rural farm solar — get a DNO connection study early.
- Battery sizing should target the largest single load pattern, not arbitrary capacity. 100 kWh sized to the cold-store evening peak delivered far more value than a 200 kWh general-purpose battery.
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