Solar PV
The honest answer is: a properly installed 4kW solar system in 2026 costs between £6,500 and £8,000 depending on your roof, your location, and the equipment your installer specifies. Larger systems cost proportionally more — a 6kW system runs £8,500–£11,500, and an 8kW+ system from £12,000 upward.
Below we break down exactly what drives those numbers, what you should and shouldn't pay for, and how to read a solar quote without getting burned.
| System Size | Panels (approx) | Annual Output | Installed Cost |
|---|---|---|---|
| 4kW | 8–10 panels | 3,400–3,800 kWh/yr | From £6,995 |
| 6kW | 12–15 panels | 5,100–5,700 kWh/yr | £8,995–£11,495 |
| 8kW+ | 16–20 panels | 6,800–7,600 kWh/yr | From £11,995 |
All prices include installation, inverter, mounting, cabling, AC/DC isolators, generation meter, and full system certification. 0% VAT applies under current HMRC rules.
A complete installation from a reputable certified installer should include all of the following — if any are missing from a quote, query it:
A simple pitched south-facing roof with no obstacles takes half the time of an L-shaped roof with a chimney stack, skylights, and a mix of pitches. Expect to add £300–£700 for complex roofs.
String inverters (one unit, handles all panels) are the most common and most cost-effective. Hybrid inverters cost more but allow battery storage to be added later without replacing the inverter — often the smarter long-term choice.
Tier 1 panels (from manufacturers with solid balance sheets and 25-year product warranties) cost more than budget alternatives. The difference over a 25-year system life is significant — don't let an installer substitute cheaper panels without disclosure.
Labour costs vary by region. Essex and Hertfordshire tend to run slightly higher than Norfolk and Suffolk due to living cost differences. The material costs are identical.
A 4kW system generating ~3,600 kWh/year saves approximately £900–£1,100/year in electricity bills (based on current Ofgem price caps) plus earns Smart Export Guarantee (SEG) payments for exported electricity. At current rates, payback is typically 6–9 years on a system with a 25-year design life.
We see this regularly. A £4,500 quote excludes scaffolding (add £800), uses budget panels without a 25-year warranty (system underperforms or fails in year 12), and the installer disappears when the inverter needs attention in year 5. The total cost of a "cheap" installation over its life frequently exceeds a properly specified one.
Ask every installer for their installer certificate number. Check it on the government certification database at mcscertified.com. If they can't provide an installer certification number, the installation will not qualify for 0% VAT, SEG payments, or many home insurance policies. Walk away.
AFTA Electrical covers Essex, Suffolk, Norfolk, Cambridgeshire, and Hertfordshire. NAPIT & TrustMark registered.
A properly installed 4kW solar system costs from £6,995 including panels, inverter, mounting, cabling, full system certification, and all electrical work. 0% VAT applies to domestic installations.
No — solar panel installations on domestic properties qualify for 0% VAT under current HMRC rules. Your installer must be registered with an approved scheme to legitimately apply the 0% rate.
Typically 6–9 years for a properly specified system, accounting for electricity savings and Smart Export Guarantee payments. The system is designed to last 25+ years.
A 4kW system suits most 3–4 bedroom homes. Larger properties or those with high electricity usage (EV, heat pump) benefit from 6–8kW. A proper survey will assess your roof and usage to recommend the right size.
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