How many solar panels fit on my roof?
Measure one side of the roof only, the side you’d put panels on. Rough measurements are fine; a 10-step stride along the house is about 7 to 8 metres.
Installers leave a gap of about 30 to 40 cm around the edges for wind and fire safety, so the panel count here allows for that. An installer will confirm on a survey.
Roof guide: measuring up
Panel size
A typical modern panel is about 1.76 m tall and 1.13 m wide, and produces up to 435 watts. Most homes fit between 6 and 14 panels.
Measuring safely
Don’t go on the roof. Count roof tiles from the ground or from a photo, or pace out the width of the house. Many houses are about 7 to 9 m wide. For the height, the slope of a typical roof is about 1.2 times the height from gutter to ridge.
What reduces the space
Chimneys, roof windows, vents and dormers all take space, and panels need to stay clear of them. Hipped roofs, which slope on all four sides, are triangular at the ends, so fit fewer panels than their width suggests.
Using two roof faces
If the best face is small, panels on east and west faces together still work well, producing about three-quarters as much as south-facing ones and spreading generation through the day.