4 kW system pricing
4 kW Solar System Cost UK 2026
A 4 kW solar PV system is the most-installed size for UK homes — it covers a typical 3-bed semi, generates 3,200–3,600 kWh per year, and pays back in 7–10 years with the right tariff. Here's what one really costs in 2026.
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What you pay
Price ranges
| Specification | Price range |
|---|---|
| Basic 4 kW (string inverter, 11 panels, no battery) | £6,500 – £7,200 |
| Standard 4 kW (with optimisers + bird mesh) | £7,500 – £8,500 |
| Premium 4 kW (Tier-1 panels, 25-yr warranty) | £8,800 – £9,500 |
| With Tesla Powerwall 3 (13.5 kWh battery) | £14,500 – £16,200 |
| With EcoFlow PowerOcean (10 kWh battery) | £13,200 – £14,800 |
| With GivEnergy AIO (13.5 kWh battery) | £13,800 – £15,400 |
Where the money goes
Cost breakdown
| Component | % of cost |
|---|---|
| Panels (11 × 380W) | 22% |
| Inverter | 15% |
| Optimisers | 5% |
| Mounting + bracketry | 6% |
| DC + AC cabling, MC4 | 2% |
| Scaffolding (3 days hire) | 8% |
| Labour (2 engineers, 1 day) | 11% |
| Paperwork (DNO + MCS + SEG) | 4% |
| Margin + overheads | 27% |
What changes the price
Variables
- Roof complexity +£200 to +£800 — split arrays, dormers, slate vs tile
- Scaffolding access +£0 to +£300 — neighbour access, narrow alleys
- DNO requirements +£0 to +£250 — G99 if export > 16A, three-phase upgrades
- Roof prep work +£200 to +£1,500 — felt replacement, slate replacement before install
- Panel choice £1,400 to £2,200 — REC AlphaPure premium vs JA Solar standard
- Inverter type String £1,200 / hybrid £1,800 / micro £2,200 (Enphase)
Return on investment
Payback model
Annual savings and payback by tariff combination. Modelled against typical UK consumption profile.
| Setup | Annual saving | Payback |
|---|---|---|
| No battery, Octopus Outgoing Fixed (15p export) | £480 | 15 years |
| No battery, Octopus Flux (24p peak export) | £560 | 12 years |
| + Tesla Powerwall, Octopus Flux | £1,184 | 12 years (£14,500 system) |
| + EcoFlow PowerOcean, Octopus Flux | £1,120 | 12 years (£13,200 system) |
Common questions
FAQs
Why does 4 kW solar cost £6,500–£9,500?
The £3,000 spread is mainly panel choice (£1,800 difference between standard and premium), inverter type (£1,000 between string and hybrid), and scaffolding/access cost (£300–£600). Choose the middle of the range for best value.
What size system is best for a 3-bed home?
4 kW is the standard. It's the largest system most permitted-development thresholds allow without planning, and matches a typical UK family's 4,500 kWh annual consumption with battery storage.
Can I finance a 4 kW system?
Yes — Phoenix Financial 0% to 10.9% APR. From £79/month over 10 years for the standard £8,000 system. Calculate yours on /finance-calculator/.
How long does the install take?
One day on the day. 6–8 hours for a standard 4 kW domestic. Scaffolding goes up the day before. Whole process from survey to commissioning is 3–4 weeks.
What's the warranty?
Tier-1 panels carry 25-year manufacturer warranty. Inverter 10 years. Workmanship 5 years from us.
Related guides
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