FREE TOOL
Roof Area & Solar Panel Calculator
Draw the outline of your roof on a satellite photo and get the usable area, how many panels fit and the system size in kW. Works for any address in Australia. You can add multiple roof sections, drag the corners to fine tune, and share the result with a link.
How do I measure my roof?
Search your address and zoom right in. Tap each corner of a roof section in order, then close the section (tap near your first corner, or use the Close this section button). Repeat for other sections if your roof has several usable faces. Drag any corner to fine tune the shape. Enter your roof tilt and the calculator converts the flat plan area you drew into the actual sloped roof surface.
How many panels fit on a typical Australian roof?
A current residential panel is about 1.76 m by 1.13 m, call it 2 m² at 440 W. A typical 6.6 kW system is 15 panels, which needs roughly 30 m² of clear roof. Most Australian homes have somewhere between 100 and 200 m² of roof, so space usually isn't the limit; orientation and shading are. The calculator assumes 75% of the drawn area is usable once you allow for edge setbacks, ridges, vents and aerials.
How accurate is this?
The satellite measurement itself is accurate to within a couple of per cent if you place the corners carefully. The panel count is deliberately conservative and indicative: a real layout depends on panel orientation, rail runs and the obstructions on your specific roof, and that's the installer's job. Use this to sanity check quotes and to see whether your roof can host the system size you have in mind.
Common questions
Do you store my address or roof outline?
No. There's no database behind this tool. If you use the Copy link button, the shape lives in the link itself, so only people you share it with can see it.
What panel size should I assume?
The default is a 440 W residential panel at 1.76 by 1.13 m, which is what most installers quote today. You can change the wattage; commercial projects often use physically larger 550 W and up panels.
Does it subtract skylights and obstructions?
Not automatically. Either draw around them, or let the built in 75% usable factor cover them. If your roof is unusually cluttered, knock the result down a bit further.
Can I measure a commercial roof?
Yes, and it works well because commercial roofs are big and simple to trace. For a flat roof, set the tilt to 0 (no slope correction) and keep in mind panels are usually mounted on 10° to 15° frames with wider row spacing, so the packing factor is lower than a pitched home roof.
Planning a system this size?
Once it is on the roof, the question changes from how many panels fit to whether every one of them is working. Solar Buddy watches your system and alerts you within 2 hours when a fault appears.