Solar Panel System Size Guide

System size comparison (2026 prices)

Today's residential panels are typically 400–450W each, meaning fewer panels are needed for the same output compared to a few years ago. All prices include 0% VAT.

• 2 kW – 5 panels (400W), ~10 m² roof space, suits flats or small terraces (£3,500–£5,000)
• 3 kW – 7–8 panels, ~14–16 m², suits most terraced homes (£5,000–£7,500)
• 4 kW – 9–10 panels, ~18–20 m², suits semi-detached homes (£5,500–£9,000)
• 5 kW – 12 panels, ~24 m², suits detached homes with higher usage (£7,500–£10,500)
• 6+ kW – 15+ panels, ~30+ m², suits large homes or those adding EV charging (£9,000–£12,000+)

Factors that affect system size

A professional site survey will assess all of these factors and recommend the optimal system for your specific home:

• Available roof space and orientation — south-facing is ideal, but east/west works well too
• Shading from trees, chimneys, or neighbouring buildings (even partial shading reduces output)
• Your household electricity consumption patterns (daytime vs evening usage)
• Whether you plan to add a battery, EV charger, or heat pump
• Budget and available funding — larger systems offer better per-kW value

Panel technology trends

Residential panels have advanced rapidly. In 2026, standard panels are 400–450W with efficiencies of 20.7–22.5% — up from 250–350W just a few years ago. Leading manufacturers like DMEGC, JA Solar, and Perlight produce panels with higher wattage per m², meaning you can generate more power from less roof space. This is especially valuable for terraced homes or properties with limited south-facing roof area.