Solar Panel Angle Calculator

The short answer

Point your panels towards the equator and tilt them at roughly your latitude. In the USA, UK and Europe that means facing south; in Australia, New Zealand and South Africa it means facing north. The further you are from the equator, the more the best angle falls below your latitude, because cloudier skies send more light from overhead.

The good news is that the exact angle doesn't matter much. In New York, any tilt from 24° to 48° facing south gets within 2% of the maximum. Most pitched roofs already sit in that window.

Best solar panel angle by latitude

If you just want a number, find your latitude below. These figures come from real weather across many sites in each latitude band, not the simple "latitude equals tilt" rule, which overshoots in cloudy northern places. Latitude works the same north or south of the equator; only the direction flips.

Best solar panel angles in major cities

Here are the best year-round and seasonal tilt angles for 28 cities, all facing the equator. The last column is how many kWh a year each kW of panels makes at the best fixed angle, after typical system losses. Search your own address in the calculator above for your exact figures.

Which direction should solar panels face?

Towards the equator gives the most energy over a year. East and west facing panels are the next best thing. At a typical 20° roof pitch they make about 82% of the maximum in New York, 80% in London and 85% in Sydney, just spread across the morning or afternoon instead of peaking at midday. That can suit a household that uses most of its power before work or in the evening.

Panels facing away from the equator (north in the USA and UK, south in Australia) do worst, but a low pitch softens the hit. At 10° they still make about 76% of the maximum in New York and 80% in Sydney. Panels are cheap enough now that a poor facing roof is often still worth filling. Our solar orientation comparison models north, east, south and west side by side for your address, season by season.

Should you adjust your panels through the year?

The sun sits higher in summer and lower in winter, so the best angle changes with the seasons: roughly 20° to 30° flatter than your year-round angle in summer and 20° to 30° steeper in winter. The calculator shows all three for your location.

In practice the gain is small. Across all 28 cities above, adjusting four times a year adds only 1% to 4% over the best fixed angle. It makes sense for an adjustable ground mount or an RV panel you can reach easily. For a roof, set it once and leave it.

How does this calculator work?

It uses a typical meteorological year of weather for your location from PVGIS, run by the European Commission's Joint Research Centre. That's hour by hour sunshine, cloud and temperature built from about 20 years of records. Our model tracks the sun through every hour of that year, works out how much light lands on a panel at each tilt using the Perez sky model, then allows for panel heat, 14% system losses and inverter efficiency.

It's the same engine as our orientation comparison tool. We checked it against NREL's PVWatts at ten locations and it landed within about 4% at nine of them; Honolulu came in about 10% high, which we put down to how the weather data handles small islands.

The percentage for your roof compares its yearly output with the best fixed angle at your location. Say you're in Sydney with a west facing roof at 20°: that's about 85%, so a 10 kW system gives up roughly 2,400 kWh a year compared with a perfect roof. Noticeable, but less than most people expect.

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 permit paperwork. 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.

Need your roof's numbers first? The roof azimuth calculator finds which way it faces from a satellite photo, and the roof pitch calculator measures the angle from a photo on your phone. To work out how many panels will fit, try the solar roof calculator.

Common questions

Add this calculator to your website

Run a solar blog, an installer site or a sustainability page? You're welcome to embed this solar panel angle calculator for free. Copy the code below into any page. It works on WordPress, Squarespace, Wix and plain HTML, and there's nothing to sign up for.

Please keep the credit line under the calculator. If you need a different size or have a question, contact us.