How many solar panels fit on my roof?

Start with the physical limit: how many 450 W panels actually fit on your roof. Enter the roof face and get the count and system size.

Enter your setup

Roof face

Roof length

One rectangular face — the one facing the sun.

Roof width

Assumptions

PanelWattage and size.

Use positive measurements and valid numbers.

SOLAR · ROOF

Panels that fit

–

Do you need solar equipment?

Residential solar panelsAmazon Solar installation kitsAmazon

Hand-picked for this exact result — no generic lists.

Assumes 175×113 cm panels with 0.6 m setbacks from roof edges (fire code in many areas).

Measure one roof face.
Use the sun-facing rectangle; complex roofs need a pro layout.
Keep the setbacks.
0.6 m from edges and ridges is required by fire codes in many jurisdictions.
Mind the shade.
One shaded panel can drag a whole string down — chimneys and trees matter.
Check the roof first.
Panels last 25+ years; don't mount them on a roof with 5 years left.

One concrete case, with the assumptions spelled out.

After setbacks, about 32 panels fit — roughly a 14.4 kW system.

ƒ(x)panels = floor((L−1.2) ÷ 1.8) × floor((W−1.2) ÷ 1.18)