How Much Does a 100 kW Factory Solar System Cost? (UK 2026)
A 100 kW factory solar system costs £80,000–£90,000 fully installed in 2026. That’s £800–£900 per kWp. Year-1 saving: £22,000–£30,000. Payback: 3.5–4 years. Suits small factory, contract manufacturer, food-prep unit sites drawing 300–500 MWh/year.
60-second answer
A 100 kW commercial solar PV system in the UK costs £80,000–£90,000 fully installed in 2026. That includes panels, inverters, mounting, structural survey, DNO G99 connection, MCS commercial certification, IWA insurance-backed warranty and commissioning.
| System size | Installed cost | Annual output | Annual saving | Payback | 25-yr saving |
|---|---|---|---|---|---|
| 100 kW | £80,000–£90,000 | ~92,000 kWh | £22,000–£30,000 | 3.5–4 yrs | ~£380,000–£450,000 |
| 50 kW factory solar cost | £45,000–£50,000 | ~46,000 kWh | £12,000–£16,000 | 4–5 yrs | ~£190,000–£230,000 |
| 250 kW factory solar cost | £187,500–£212,500 | ~230,000 kWh | £55,000–£72,000 | 3–4 yrs | ~£950,000–£1.1m |
Figures assume a Mon–Fri daytime load profile and the Q1 2026 industrial grid rate of ~28–30 p/kWh. Get site-exact numbers with our industrial solar panel ROI calculator.
Running a smaller unit with under 500 sqm of roof? Our full breakdown of 50kW solar system cost UK covers the £45,000–£50,000 price band, panel counts and 4–5 year payback in the same detail as this page.
- Cost per kWp installed: £800–£900
- Number of panels: 180 (at 545–625 W each)
- Roof area required: ~600 sqm of unobstructed roof
- Annual generation: ~92,000 kWh
- Year-1 saving: £22,000–£30,000 (against current Q1 2026 grid rate of 27.69 p/kWh)
- Simple payback: 3.5–4 years on capital purchase
- Tax treatment: 100% AIA in year 1 covers up to £1m of capex — effective post-tax cost £60,000–£67,500. Note: solar is a special-rate asset, so capex above the £1m AIA cap attracts 50% first-year allowance, not full expensing.
Is a 100kW system right for your factory?
A 100 kW array suits sites with roughly 600 sqm of clear roof and an annual electricity demand of 200–500 MWh. Use this table to sanity-check fit before you request a quote:
| Factory type | Typical roof m² | Annual kWh use | Fit for 100 kW |
|---|---|---|---|
| Small/light engineering workshop | 300–450 | 80,000–150,000 | Often oversized — see 50 kW factory solar cost |
| Contract manufacturer / food-prep unit | 600–900 | 200,000–450,000 | Ideal fit |
| Single-line production plant | 800–1,200 | 400,000–600,000 | Good — consider 150–250 kW for more offset |
| Multi-shift / heavy process plant | 1,500+ | 700,000+ | Undersized — step up to 250 kW factory solar cost |
Self-consumption (using power on site rather than exporting) is what drives payback. A 100 kW system performs best where the factory’s weekday daytime load comfortably exceeds 100 kW for most operating hours.
What’s included in the 100kW price
Every line item that goes into the fully-installed price for a UK commercial solar system this size:
- Panels (Tier-1 TOPCon n-type, e.g. Jinko Tiger Neo 580W or Trina Vertex 605W) — 35–42% of total cost
- Inverters (Sungrow / Huawei / SMA / Fronius) — 12–15%
- Mounting and rails (clamp-fix on standing seam, rail-mount on profiled metal, ballasted on flat) — 8–12%
- DC and AC cabling, isolators, combiners — 5–7%
- Labour and project management — 12–18%
- Scaffolding and access — 3–6%
- Structural survey, electrical design, PVSyst yield modelling — 3–5%
- DNO G99 connection (application fee, study, connection works) — 4–8%
- MCS commissioning, IWA warranty, commissioning certificate — 2–4%
The lower end of the price range applies to easy installs — standing seam metal roof, three-phase supply already in place, no grid reinforcement needed. The upper end applies where any of: roof refurbishment is required, single-phase supply needs upgrading, scaffolding is complex, or DNO grid reinforcement adds £15–£75k.
100kW equipment & install cost breakdown
Indicative £ split on a typical £85,000 fully-installed 100 kW project:
| Line item | Detail | Indicative cost |
|---|---|---|
| Panels | 180 × 555–580W Tier-1 TOPCon | £30,000–£35,000 |
| Inverter(s) | 100 kW three-phase string inverter(s) | £11,000–£13,000 |
| Mounting & rails | Roof-type specific (clamp/rail/ballast) | £7,000–£10,000 |
| DC/AC cabling & protection | Cable, isolators, combiners, AC works | £4,500–£6,000 |
| Scaffold & access | Edge protection / MEWP hire | £3,000–£5,000 |
| DNO G99 connection | Application, study & connection (>50 kWp) | £3,500–£7,000 |
| Install labour & PM | 2–5 day install + project management | £11,000–£15,000 |
Systems over 50 kWp require a full G99 application to your DNO (NGED, UKPN, ENWL, SPEN or Northern Powergrid depending on region) — we initiate this before contract because it is the longest lead item.
Adding battery storage to a 100kW system
Battery storage lets you bank midday surplus and use it during evening shifts or peak-rate windows instead of exporting at the lower SEG rate. For a 100 kW array, a 100–215 kWh commercial battery is the common pairing. Commercial battery storage runs roughly £400–£700 per kWh installed, falling with size.
| Battery size | Indicative installed cost | Best for | Payback impact |
|---|---|---|---|
| 50 kWh | £25,000–£35,000 | Light evening load / shoulder shifts | Adds ~1–2 yrs to blended payback |
| 100 kWh | £45,000–£65,000 | Two-shift sites raising self-consumption | Adds ~1.5–3 yrs; lifts self-use to 80%+ |
| 215 kWh | £90,000–£130,000 | Peak-shaving high evening/night demand | Adds ~2–4 yrs; strongest where peak rates are high |
Storage stacks best where you have high spread between peak and off-peak rates, a meaningful evening load, or you want to use solar to peak-shave demand charges. We model battery vs no-battery side by side in every feasibility study.
How a 100kW factory solar system pays back
For a typical UK factory operating Mon–Fri 8am–6pm with the load profile that matches a 100 kW system, the simple payback runs 3.5–4 years on capital purchase. Here’s the math:
- Capex: ~£85,000 fully installed
- Annual self-consumption saving: ~£26,000 year 1, escalating ~3% per year against grid
- SEG export income: ~£2,600/year on the 12–25% of generation that exports
- O&M cost: £8–£12 per kW per year — for 100 kW that’s ~£1,000/year
- AIA tax relief: 100% of capex deductible year 1 — saves ~£21,250 in cash tax at 25% corporation tax
- 25-year cumulative saving (NPV @ 7%): roughly 4–5x the initial capex
IRR over 25 years for a 100 kW install lands at 18–28% — well above any board’s hurdle rate. The system runs for 30–35 years with one inverter replacement at year 12–15.
Financing routes for this size
For a £80,000–£90,000 install, the four mainstream financing routes:
- Capital purchase + AIA — pay £80,000–£90,000 cash, claim 100% first-year tax relief. Best NPV. Ties up capex.
- Asset finance / lease-to-own — spread cost over 5–15 years at 5–8% interest. Cash-flow positive from month 1 at most sites of this size. Take ownership at term-end.
- PPA (Power Purchase Agreement) — third party owns and operates the 100 kW system, you buy the kWh at 15–30% below grid for 15–25 years. Zero capex, lower 25-year value but no upfront cash.
- Green business loan — 100% finance at 4–8% interest, 5–15 years. You own the asset immediately. Loan repayments typically below energy savings from month 1.
See our full factory solar financing guide for side-by-side modelling.
100kW factory solar — FAQs
How much roof do I need for a 100 kW solar PV system?
About 600 sqm of unobstructed roof for portrait-mounted high-power panels. Slightly more if the roof has chimneys, AHUs, parapets or shading, slightly less for east-west bifacial layouts on flat membrane roofs.
How many solar panels in a 100 kW system?
180 panels in 2026 (using 545–625W TOPCon n-type modules). The exact count depends on panel wattage selected, roof orientation, and whether you use bifacial or monofacial.
How long does a 100 kW install take?
2–5 days physical install for 100 kW, plus DNO connection (final 4–8 hour outage scheduled at weekend or shutdown). Total project from contract to commissioned: 8–14 weeks (the long pole is G99 grid connection, 6–18 months DNO timeline, which we initiate before contract).
Will a 100 kW system cover my factory’s full electricity demand?
For a factory drawing 300–500 MWh/year, a 100 kW system typically offsets 40–65% of annual demand. To get to 100% renewable, combine with a green PPA on a remote solar farm or with a green energy supplier.
Can I get a 100 kW solar PV system on PPA with no capex?
Yes — multiple UK PPA providers operate at this size. Standard form: 15–25 year contract at 12–18 p/kWh fixed, with annual escalation tied to RPI or fixed at 1–2%. Day-one positive cash flow vs current 27.69 p/kWh grid retail.
Ready to price up a 100 kW system for your factory?
Free desk-based feasibility from your half-hourly meter data within 7 working days. Includes capex, AIA tax relief, NPV, IRR and PPA-vs-capital comparison.
Get a Free 100kW Factory Solar QuoteWant exact numbers for your site? Calculate your factory solar ROI — model payback, IRR and 25-year savings for a 100KW system in 60 seconds.
Many operators add batteries later: see the full guide to battery storage for factory solar for costs per kWh and use cases.
Our vetted approved solar panel installers all carry MCS certification.
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