How the tilt angle calculator works
This tool estimates the tilt angle - how steeply your panels should lean back from flat - and the compass direction they should face, based on your latitude. Tilt and direction (azimuth) together determine how directly sunlight hits your panels through the year, which has a real effect on total output.
Enter your latitude manually, or tap the location button to use your browser's GPS. The calculator detects your hemisphere automatically from the sign of the latitude (positive for north, negative for south) and returns a recommended fixed tilt, plus optional seasonal and monthly adjustments if you want to fine-tune further.
The formula in plain English
For a fixed, year-round tilt, the calculator uses a latitude-based rule with three bands:
- Below 25° latitude:
Tilt = Latitude × 0.87 - 25° to 50° latitude:
Tilt = Latitude × 0.76 + 3.1 - Above 50° latitude:
Tilt = Latitude × 0.5 + 16
These bands reflect how the sun's average height in the sky changes with latitude - near the equator the sun sits high overhead most of the year, so a shallow tilt works well, while at higher latitudes the sun stays lower and panels need to lean back further to catch it directly.
Optimal fixed tilt for cities around the world
| City | Latitude | Optimal fixed tilt | Panels face |
|---|---|---|---|
| Singapore | 1°N | ~1° | South |
| Lagos | 6°N | ~5° | South |
| Karachi | 25°N | ~22° | South |
| Delhi | 29°N | ~25° | South |
| Los Angeles | 34°N | ~29° | South |
| Sydney | 34°S | ~29° | North |
| London | 51°N | ~42° | South |
| Berlin | 52°N | ~42° | South |
Notice Sydney and Los Angeles share almost the same tilt despite being in opposite hemispheres - the math only cares about distance from the equator, not which side of it you're on. What changes is the facing direction: southern hemisphere panels face north, northern hemisphere panels face south.
Seasonal tilt adjustments
If your racking allows it, adjusting tilt with the seasons captures more energy than a single fixed angle, because the sun's path is much higher in summer and much lower in winter. A common approach uses four settings a year, or a simpler two-setting summer/winter swap:
- Summer tilt ≈
Latitude × 0.9 − 23.5 - Winter tilt ≈
Latitude × 0.9 + 29 - Spring/autumn tilt ≈
Latitude − 2.5
For a location at 29° latitude, that works out to roughly 3° in summer, 55° in winter, and 27° in the shoulder seasons - a big swing, which is why seasonal adjustment is more common on ground-mounted or off-grid systems with accessible racking than on a fixed roof mount.
Fine-tuning tilt month by month
For anyone who wants to adjust tilt more than four times a year, the calculator can also estimate a monthly optimal tilt using the sun's solar declination - how far the sun's direct rays sit north or south of the equator on a given day. The relationship is:
Monthly tilt = Latitude − Solar declination, where Declination = 23.45 × sin(360 ÷ 365 × (284 + day of year))
In practice this just means: tilt flattens out in summer months (when declination is high) and steepens in winter months (when declination is negative), tracking the sun's seasonal path across the sky. Few residential installs bother with monthly adjustment, but it's useful for off-grid or portable setups where squeezing out extra output matters.
Azimuth: which direction to face your panels
Tilt controls the lean angle; azimuth controls the compass direction the panels face. As a rule of thumb:
- Northern hemisphere: face true south (180°)
- Southern hemisphere: face true north (0°)
True direction is based on the geographic pole, not a compass reading. A compass points to magnetic north, which can differ from true north by anywhere from near zero to over 20 degrees depending on where you are, an offset called magnetic declination. Use a phone's GPS-based "true north" compass mode, or look up your local magnetic declination online, before marking out azimuth on a roof.
If true south or north isn't available - for example, on a roof that only faces southeast and southwest - an east-west split array, with half the panels on each face, is often a reasonable compromise that trades a bit of peak output for a flatter, longer production curve across the day.
Flat roofs, ballast frames and snow shedding
Flat commercial and residential roofs need a ballasted tilt frame to angle panels properly, since there's no roof pitch to work with. These frames typically set panels between 10° and 20°, held down by weighted bases rather than roof penetrations, which keeps the install non-invasive but also limits how steep the angle can practically go without excess wind load and spacing between rows.
A tilt of at least 10° also helps panels shed rain and dust on their own, which matters for keeping output consistent between cleanings. In snow-prone regions, installers often favor a steeper angle - sometimes above what's mathematically optimal for annual output - specifically so snow slides off rather than sitting on the panels and blocking sunlight for days at a time.