Why polytunnels & glasshouses are an excellent fit for commercial rooftop PV
Heated UK glasshouses and large polytunnel complexes — particularly those producing salads, soft fruit, ornamentals, propagation, vertical-farm crops or year-round protected horticulture — have some of the largest commercial electrical demand profiles in UK agriculture. Supplementary lighting (LED grow-light systems running 14–18 hours per day in winter), heating (typically gas or biomass with electric heat-pump augmentation increasing), HVAC, irrigation pumps, and packing-line equipment combine to push annual electricity consumption for a mid-sized commercial glasshouse to 1–3 GWh, with the largest sites consuming 10+ GWh annually. The roof area available is correspondingly large — glasshouse complexes commonly cover 1–5 hectares with semi-transparent glazing, while polytunnel complexes can extend across 5–20 hectares. Agrivoltaic deployment over polytunnels (using semi-transparent panels above shade-tolerant crops) is emerging quickly in the UK.
System sizing for polytunnels & glasshouses
Glasshouse and polytunnel PV sizing depends heavily on the structure type. Conventional Venlo glasshouses with steel-frame construction can support rooftop PV on the structural ridge framework (typically 80–200 kW per hectare of glasshouse footprint), with the remainder of the glazing kept clear for natural light. Polytunnel installs are more complex — most polytunnels are designed for the polythene cladding to be replaced every 4 years, which complicates fixed rooftop PV. The emerging solution is elevated agrivoltaic installs (raised structural frames above the polytunnel with semi-transparent panels) or ground-mount installs on adjacent paddocks dedicated to PV. Vertical farm (CEA) sites with sealed enclosed buildings typically install PV on the building envelope or on adjacent ground-mount fields.
Typical polytunnels & glasshouses install at a glance
- System size range
- 100 kW–2 MW
- Panel count
- 185–3,700
- Roof area needed
- 600–12,000 sqm
- Project value
- £90,000–£1.8m
- Typical simple payback
- 5.5 years
- Annual generation
- 92,000–1.85m kWh
- Annual CO2 avoided
- 21–425 tonnes
Cost and economics
Glasshouse and polytunnel install economics in 2026: £90,000–£1.8m typical project value, 5.5-year simple payback, 92,000–1.85m kWh annual generation. The scale of typical projects (often above 500 kW, sometimes above 2 MW) means PPA financing is widely used in this segment — third-party developers fund, install, own and operate the PV system on the glasshouse complex in exchange for a discounted-rate Power Purchase Agreement over 15–25 years. We model PPA, asset finance and capital purchase routes side-by-side in every glasshouse proposal. For supermarket-direct salad and soft-fruit growers, the supplier-audit positioning is increasingly central to the install business case alongside direct cost reduction.
Compare these numbers against the wider cost of farm-building solar in 2026 and the grants and finance routes available. We provide full DCF financial models with PVSyst yield modelling and 25-year IRR projections in every fixed-price proposal.
Compliance and regulation
Agrivoltaic translucent-panel installs over polytunnels need agronomic trial alongside structural assessment — different crops have different shade tolerance, and the PV-shading effect on yield must be modelled before full deployment. Polytunnel structural reinforcement is often required for any rooftop PV — typically a complete frame upgrade or, more commonly, perimeter ground-mount as a cleaner alternative. Glasshouse installs avoid these complications because the structural frame already supports significant dead load. Defra and NFU horticulture engagement on agrivoltaics is increasing — SFI 2025 has begun to recognise agrivoltaic schemes within biodiversity-adjacent action bundles. Planning policy for ground-mount alongside polytunnel complexes follows the standard 9m × 9m × 4m Permitted Development cap with full planning above.
Install programme and timeline
Glasshouse and polytunnel install timeline: weeks 1–6, survey, agronomic assessment (for agrivoltaic options), structural and electrical design, financial modelling across PPA/asset finance/capital scenarios; weeks 6–10, contract finalisation and DNO G99 application (large installs may require capacity studies running 90–180 days); weeks 10–24, procurement, planning consultation if required (typically for ground-mount above 9m × 9m × 4m), structural reinforcement works if required; weeks 24–32, install — 4–8 weeks for a 1 MW glasshouse or polytunnel-adjacent ground-mount install; weeks 32–34, commissioning and supplier-audit documentation generation.
A representative recent polytunnels & glasshouses install
A typical UK glasshouse install: a Kent-based salad-grower running 4 hectares of heated Venlo glasshouses supplying a major UK supermarket with year-round leaves and herbs. Annual pre-install electricity spend £820,000 across HVAC, supplementary lighting, packing-line, and biomass-boiler auxiliaries. We delivered 1.2 MW PV across the southern ridge of the glasshouse complex (using structural-frame mounting that doesn't shade the growing area) and a 600 kW ground-mount on adjacent unused paddock. A 500 kWh battery system supports the lighting demand peak that runs in winter mornings. First-year generation 1.7 GWh. Annual saving £410,000 across cost avoidance and SEG export. Simple payback 4.9 years. The install featured in the supplier's 2025 CDP Supply Chain return and supported renewed supermarket supply terms.
See more examples in our case studies library — we publish full project narratives across every sub-vertical we work in.
Key features and capabilities for polytunnels & glasshouses
- Heated glasshouses and protected horticulture have massive supplementary lighting and heating loads
- Vertical farming and CEA sites exceptionally good PV fit
- Agrivoltaics over polytunnels emerging quickly (translucent panels, semi-shade-tolerant crops)
- Soft fruit, salads, ornamentals — supermarket-facing producers under Scope 3 pressure
Get a fixed-price proposal for your polytunnels & glasshouses install
Every quote starts with a free desk-based feasibility study from your half-hourly meter data and building dimensions. We share an indicative system size, generation forecast, self-consumption ratio, and 25-year financial model within 7 working days. If the numbers work, our engineers visit for a one-day structural and electrical survey, after which we deliver a fixed-price proposal with full PVSyst yield modelling and DCF financial model. Most polytunnels & glasshouses installs commission in 4–7 months from contract; combined re-roof + PV programmes add 2–3 months. Send your meter data via our quote form or contact us directly to get started.
Common questions
How much do solar panels for farm buildings cost in the UK?
For a typical UK farm-building PV install in 2026, cost per kW is roughly £900–£1,100 for systems under 50 kW (small barn, dairy parlour, equestrian arena), £800–£950 per kW for 50–250 kW systems (typical livestock shed, mid-size grain store, poultry shed), and £700–£850 per kW for systems above 250 kW (large multi-bay barns, intensive poultry or pig units, big grain stores). Combined re-roof and PV (asbestos replacement) adds £25–£45/sqm to capex but is often the only viable path on pre-2000 buildings. We provide a fixed-price proposal within 7 working days of receiving meter data and roof dimensions.
Can we put solar panels on asbestos cement barn roofs?
No — asbestos cement roofs must be replaced before any rooftop PV install. The Control of Asbestos Regulations 2012 prohibits drilling, fixing, or load-imposing on asbestos cement sheeting. The standard approach is a combined re-roof + PV project: a licensed asbestos contractor removes the cement sheets, the structure is upgraded if needed, profiled steel or membrane is installed, then PV mounts to the new roof. The PV business case routinely pays for 60–100% of the re-roof cost over the 25-year system life.
Which farm building should we install solar on first?
Prioritise by three criteria: (1) roof area and orientation — the biggest south-facing clear-span roof in sound structural condition wins; (2) on-site daytime load — dairy parlours, grain stores during harvest, intensive livestock houses, and farm workshops all have year-round or seasonal daytime baseload; (3) install access and biosecurity complexity — workshops and grain stores typically have lower biosecurity friction than poultry or pig units, but the latter often have much larger roofs. We rank each building during feasibility on payback, self-consumption, and complexity.
Will solar panels work on a curved or arched barn roof?
Generally no — modern PV requires a structural surface with adequate purlin spacing and slope (typically 5° to 35°). Curved Dutch-barn or hooped sheds need either a separate flat or pitched roof to be installed (rare), a ground-mount alternative, or — most commonly — a different building on the farm chosen as the PV host. We assess every farm holistically rather than fixating on a single building.
What grants are available for farm-building solar in 2026?
Headline schemes: 100% Annual Investment Allowance (universal — up to 25% effective tax saving year one), Sustainable Farming Incentive (SFI 2025 actions for biodiversity and agrivoltaic pairings), Farming Investment Fund (capital grants on solar-paired investments like robotic milking or grain dryers), Smart Export Guarantee (8–15p/kWh on surplus export). Welsh and Scottish farms have additional devolved schemes (Rural Investment Schemes) often with higher intervention rates than English equivalents.
Do we need planning permission for solar on agricultural buildings?
Most rooftop installs on agricultural buildings fall under Class A Part 14 GPDO 2015 Permitted Development — no planning permission needed. The exceptions are: listed agricultural buildings (Listed Building Consent required), National Parks and AONBs (sometimes Article 4 directions in force), Conservation Areas, and ground-mount above 9m × 9m × 4m height. We handle planning consultation as part of every project — typically a 4–8 week timeline if planning is required.