FREE TOOL
Solar Panel Angle Calculator
Enter your roof's direction (azimuth), its tilt and your postcode, and see how much of the maximum possible solar yield your roof captures. Built on long term Australian sun data, so it works for Australian locations only. Don't know your numbers? The azimuth and tilt calculators below will find them for you.
How does this calculator work?
Under the hood is a solar geometry model that tracks the sun's position hour by hour across a full year for your latitude, with typical Australian sky conditions applied. We generated the underlying data with pvlib, the open source solar modelling library used by solar engineers and researchers, and sense checked the ratios against NREL's PVWatts. The result you see is your roof's annual solar capture compared with the best possible fixed angle at your location.
What do the percentages actually mean?
100% is the most a fixed roof can collect at your latitude: facing north at close to the ideal tilt. Say you're in Sydney with a west facing roof at 20°. That works out around 90%, so a 6.6 kW system would give up roughly 900 kWh a year compared with a perfect roof. At 25c/kWh that's about $230. Real money, but far less than most people expect, and less than a single faulty panel string can quietly cost while nobody's looking.
Should I use tilt frames to get a better angle?
On a pitched roof, almost never. The gain from correcting a 20° roof to the ideal angle is a few per cent, and tilt frames cost more than that extra energy is worth. They also add wind load and council considerations. On a flat roof they make more sense: panels laid dead flat lose a bit of yield and don't self clean when it rains, so a 10° to 15° frame is the usual answer there.
Common questions
Why does direction matter less than I thought?
Because a big share of the solar energy hitting your roof is diffuse light scattered by the sky and clouds, and that arrives from everywhere. Only the direct beam really cares which way your panels point. That's why even a south facing roof in Sydney still collects about 80% of a north facing one.
Is this exact for my address?
It's based on your latitude and long term average sky conditions for your region, so treat it as a solid indicative figure, not a quote. It doesn't know about your local microclimate or shading, and shading in particular can matter more than orientation.
Does it work outside Australia?
Not yet. The sun data behind it covers Australian latitudes, and the postcode lookup is Australian only.
What about shading from trees or buildings?
Not modelled here. Shading is very site specific: a chimney shadow that crosses one panel for two hours a day can cost more than facing the wrong way entirely. An installer's shade analysis (or a monitoring service that spots underperformance) is the way to catch it.
Own solar already?
Orientation sets the ceiling on what your system can produce. Faults decide whether it gets there. Solar Buddy connects to your inverter, learns how your system should perform and alerts you within 2 hours when something goes wrong.