2026/27 STATUTORY & COST AUDIT • ICO REG ZC136598
4kW (10 Panel) vs 6kW (14 Panel) Solar System Cost & Payback in the UK (2026)
Is it worth upgrading from a 4kW to a 6kW solar panel system in the UK?
Yes. Because fixed installation costs—HSE scaffolding (£650), hybrid inverter (£1,150), MCS certification, and DNO commissioning—remain identical, expanding from a 4.4 kWp (10 x 440W) array to a 6.16 kWp (14 x 440W) array increases upfront cost by only ~18% (£1,140 extra) while boosting annual generation by 40% (+1,670 kWh/yr), shortening payback by 1.1 years.
| Array Configuration | Turnkey Cost (with 5.1kWh Battery) | Annual South-Facing Yield | Estimated Annual Savings + SEG |
|---|---|---|---|
| 3.52 kWp (8 x 440W Panels) | £7,000 (0% VAT) | 3,340 kWh / yr | £890 / yr |
| 4.40 kWp (10 x 440W Panels) | £7,570 (0% VAT) | 4,180 kWh / yr | £1,095 / yr |
| 6.16 kWp (14 x 440W Panels) | £8,710 (0% VAT) | 5,850 kWh / yr | £1,460 / yr |
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