The simple math — and the practical details
Panel count is system watts ÷ panel watts, always rounded up. A 7 kW system with 585 W panels needs 12 panels. But the practical part matters more: panels must fit your roof with room for airflow and cleaning access, and strings must match your inverter's voltage windows.
Choosing panel wattage
In 2026 the sweet spot for home installs is 585–610 W N-type panels. Bigger panels mean fewer mounts and connections, but they are heavier to handle on stairs and small roofs. If your roof is tight, high-efficiency panels (22%+) deliver more power per square foot.
How many solar panels do I need for 5 kW?
With today's common 585 W panels, a 5 kW system needs 9 panels (8.55 would be exact, so round up). Higher-watt panels reduce the count.
Do more efficient panels produce more energy?
Per square metre, yes — efficiency matters when roof space is tight. For the same kW rating, total output is similar; you simply need fewer square feet.
How much roof space does one panel take?
A modern 585 W panel is roughly 21.6 ft² of glass; with spacing and walkways, plan 60–70 ft² of roof per kW installed.