Solar panels for factories — the UK 2026 guide
Manufacturing is one of the strongest sectors for commercial solar in the UK. Big roofs, heavy daytime loads, and rising CCL-inclusive grid tariffs combine into some of the fastest paybacks in the market. This guide covers roof suitability, load matching, grid rules, indicative CapEx and how Full Expensing shifts the maths.
Short answer
A typical UK factory can host 500 kWp–1 MWp of rooftop solar, cutting the electricity bill by 30–55% and paying back in 4–6 years. Full Expensing returns 25p per £1 of CapEx for a limited company.
Pre-install checklist
- Roof age and remaining life — factories on 20+ year old built-up-felt roofs may need re-covering before or during install.
- Structural loading — an aluminium mounting system adds ~15 kg/m²; most steel-portal factories cope easily, but old brick-and-timber mills need a structural sign-off.
- Half-hourly load — pull 12 months of HH data from your supplier; the goal is to match at least 60–75% of solar output to on-site load.
- Grid connection — a G99 up to 1 MW is usually straightforward; over 1 MW you're into HV works and a formal DNO connection offer.
- Process load timing — single-shift daytime factories are the sweet spot. 24/7 lines still work well but benefit more from a battery.
Matching solar to a factory load profile
Single-shift factories running 07:00–17:00 match roughly 70–80% of solar generation directly to load, giving the fastest payback. Two-shift and 24/7 operations still consume most solar directly, but a battery to shift midday surplus into the evening peak lifts self-consumption another 5–15 points and shortens payback.
Compressed air, chillers, extractors — where the savings land
The heaviest daytime loads in a UK factory — compressors, chillers, HVAC, extraction, ovens, injection moulding — are exactly the loads solar offsets. Where a battery is added, it's usually to cover start-up peaks (compressors) or evening finishing runs.
Grid connection — G99, G100 and HV
Under 1 MW at LV: a standard G99 application, typically 4–8 weeks. Where the DNO can't accept full export, a G100 export-limited scheme keeps the site on the existing connection. Over 1 MW or on an HV supply: a full connection offer is needed — allow 3–6 months and plan CapEx for any DNO reinforcement.
Full Expensing for manufacturers
A limited-company manufacturer deducts 100% of solar CapEx from taxable profits in year one under Full Expensing, worth 25% at the main corporation tax rate. A £500,000 array has an effective net cost of £375,000 after tax relief.
Related reading
FAQ
Are factories good candidates for solar in the UK?
Yes — factories typically have large uninterrupted south- or east/west-facing roofs, heavy daytime electrical loads, and a HV or LV connection with headroom. Self-consumption often exceeds 80%, which is the strongest driver of solar payback.
How big a solar system fits on a typical UK factory?
As a rule of thumb, 1 kWp needs ~5 m² of usable roof. A 5,000 m² factory roof supports around 700–900 kWp of PV after keeping walkways, roof lights and services clear.
How much do solar panels cost for a UK factory?
In 2026, factory-scale rooftop solar costs £650–£850 per kWp installed. A 500 kWp system is typically £360k–£410k, dropping to under £700/kWp at 1 MWp+.
What's the payback on solar for a manufacturing site?
Most UK factories see 4–6 year payback at 2026 grid prices. Full Expensing takes an additional 25% off the effective CapEx for limited companies, often bringing payback under 4 years for 500 kWp+ systems.
Will installation disrupt production?
No. Rooftop installs happen entirely outside the production envelope with MEWPs or scaffolding. The only downtime is a 4–8 hour DNO cut-over at commissioning, scheduled at weekends or overnight.
Do factories need G99 approval?
Yes — any generation over 3.68 kW single-phase or 11 kW three-phase needs G99. Systems over 1 MW usually need a formal HV connection offer from the DNO.
Feasibility for your factory
Two minutes in the calculator gives an indicative system size, CapEx range and payback.