Best Solar Panel Angle for 30 Major Cities

"Tilt your panels at your latitude and face them south." You've probably seen that advice. It's fine as a starting point, but it completely ignores weather. We ran the numbers for 20 cities using a year of historical weather data, and in a lot of places the optimal angle is noticeably different from what the formula says.

Two angles, one question

For every city below, we calculated two sets of optimal angles. The first uses clear-sky physics only, the way most online calculators work. The second folds in real cloud cover, humidity, and atmospheric data from 2025. Comparing the two tells you how much local weather actually shifts things.

North America

The interesting bits

Every coastal city in this table has its weather-adjusted azimuth shifted west of due south. San Francisco and LA both land at 215°. Seattle, Houston, Miami are in the 195-205° range. The cause is morning fog and coastal clouds that burn off by afternoon. If your mornings are cloudier than your afternoons, your panels should favor the afternoon sun.

Phoenix barely moves. Clear skies year-round mean the textbook answer is basically right. Tilt drops by 2 degrees and the azimuth stays at 180°.

The other pattern: weather tends to flatten the tilt. Chicago goes from 40° to 35°, New York from 39° to 36°. Cloudy skies produce more diffuse light, which comes from all directions rather than one point in the sky. Flatter panels catch more of it.

Europe

The interesting bits

None of the European cities shift their azimuth. They all stay pointed south. But the tilts drop a lot. Stockholm goes from 52° down to 43°. That's a 9-degree gap, the biggest in this table. When you're overcast most of the year, diffuse light is the main game, and flatter panels win.

London and Paris sit at similar latitudes but London produces about 5% less energy per year. The UK is just that much cloudier.

Asia and Middle East

The interesting bits

Singapore is wild. At 1° north of the equator, theory says tilt your panels at 1°, basically flat. But the weather-adjusted number is 7°. Why? At the equator, sun angle barely matters. What matters is shedding rain and dust, and a slight tilt does that.

Dubai has a slight westward shift (195°), probably from afternoon haze and humidity. Not huge, but worth noting if you're optimizing a large installation there.

Southern hemisphere

The interesting bits

Down here, panels face north instead of south. Sydney's weather-adjusted azimuth shifts to 335° (north-northwest). Afternoon coastal clouds push the optimum slightly eastward. It's the mirror image of what happens in San Francisco and LA.

So what's the takeaway?

The "tilt equals latitude" rule is a useful shortcut but it consistently overshoots in cloudy climates, sometimes by 13 degrees. The azimuth question is even more underappreciated. In coastal cities, the optimal direction can shift 15-35° west because of morning fog and clouds. Desert cities are the exception where theory and reality basically agree.

The range across this list is almost 2x: Mexico City gets 2,380 kWh/m² per year, Stockholm gets 1,266. Where you are matters far more than most optimization guides acknowledge.

Methodology

Solar irradiance modeled with pvlib. We brute-force every combination of tilt (0-90°, 1° steps) and azimuth (0-360°, 5° steps). The theoretical model uses clear-sky radiation. The weather-adjusted model uses historical cloud cover, humidity, and atmospheric data from Open-Meteo for 2025.

The target metric is total Global Tilted Irradiance (GTI) in kWh/m², which accounts for direct, diffuse, and ground-reflected light hitting the panel surface.

You can run the same calculation for any location with our calculator.