About the solar angle calculator
A solar angle calculator returns the tilt, azimuth, and noon elevation that point a fixed solar panel as close to perpendicular to the sun's mid-day rays as possible across the year. For a fixed array, the practical rule is "tilt equals latitude, face the equator", with optional seasonal adjustment of plus or minus 15 degrees.
How it works
The Earth's axis is tilted 23.44 degrees relative to its orbital plane. The sun's declination (its apparent position north or south of the equator) swings between plus 23.44 degrees at the June solstice and minus 23.44 degrees at the December solstice. A fixed panel's annual-average best angle is the one that splits this swing, which works out to roughly the local latitude.
Year-round tilt = Latitude Summer tilt = Latitude - 15 Winter tilt = Latitude + 15 Spring / fall tilt = Latitude Solar elevation noon = 90 - Latitude + Declination Azimuth (N hemi) = 180 degrees (due south) Azimuth (S hemi) = 0 / 360 degrees (due north)
- Tilt: angle of the panel face from horizontal.
- Azimuth: compass direction the panel faces. True north / south, not magnetic.
- Declination: ranges plus 23.44 (June) to minus 23.44 (December).
- Elevation: how high the sun climbs at solar noon.
Worked example
Phoenix, Arizona sits at latitude 33.4 degrees north. A homeowner installs a fixed-tilt array.
- Year-round tilt: 33.4 degrees from horizontal.
- Azimuth: 180 degrees (due south).
- Summer tilt: 33.4 minus 15 = 18.4 degrees (flatter, sun is high).
- Winter tilt: 33.4 plus 15 = 48.4 degrees (steeper, sun is low).
- Noon elevation, June solstice: 90 minus 33.4 plus 23.44 = 80.04 degrees (nearly overhead).
- Noon elevation, December solstice: 90 minus 33.4 minus 23.44 = 33.16 degrees (low and southerly).
Tilt, azimuth, and noon elevation by latitude
| Latitude band | Example city | Year-round tilt | Summer tilt | Winter tilt | Noon elevation (June) | Noon elevation (December) |
|---|---|---|---|---|---|---|
| 0 to 10 degrees | Singapore (1.3 N) | 1 to 10 degrees | 0 (flat) | 15 to 25 | ~75 | ~65 |
| 10 to 25 degrees | Mumbai (19.1 N) | 19 to 25 | ~5 | ~34 | ~85 | ~47 |
| 25 to 35 degrees | Phoenix (33.4 N) | 33 to 35 | ~18 | ~48 | ~80 | ~33 |
| 35 to 45 degrees | New York (40.7 N) | 40 to 45 | ~26 | ~56 | ~73 | ~26 |
| 45 to 55 degrees | London (51.5 N) | 51 to 55 | ~37 | ~67 | ~62 | ~15 |
| 55 to 65 degrees | Stockholm (59.3 N) | 59 to 60 | ~44 | ~74 | ~54 | ~7 |
Azimuth: 180 degrees (due south) in the northern hemisphere; 0 / 360 degrees (due north) in the southern hemisphere. Use true north, not magnetic.
Common pitfalls
- Magnetic vs true north. A compass points to magnetic north. Magnetic declination varies by location (about 13 degrees west of true north in Seattle, near zero in Chicago). Correct for it or use a sun-position app.
- Roof slope already counts. If your roof pitches at 30 degrees and you mount panels flush, your panels are at 30 degrees, not zero. Only add tilt frames if the roof pitch deviates strongly from latitude.
- Shading beats angle. A perfectly tilted panel shaded for two hours per day produces less than a sub-optimally tilted panel in full sun. Site survey before micro-optimising tilt.
- Snow loading on steep winter tilt. A 60-degree winter tilt sheds snow well but loads the rack. Check structural ratings before going steeper than 45 degrees in snow country.
- Flat-roof commercial arrays. Wind uplift and inter-row shading often push commercial flat-roof tilts to 10 to 15 degrees regardless of latitude.
- Diffuse light at high latitudes. Above 55 degrees latitude, much of the annual yield comes from diffuse cloud-bounce light, not direct beam. A near-vertical tilt for winter direct sun underperforms because the diffuse gain drops.
Related tools and glossary
Frequently asked questions
What is the best angle for solar panels?
The optimal year-round tilt angle is approximately equal to your latitude. At 40 degrees latitude, tilt panels at 40 degrees facing the equator. Seasonal adjustments of plus or minus 15 degrees can lift annual output by 5 to 10 percent.
Does solar panel angle really matter?
Yes. A panel tilted to local latitude produces 10 to 25 percent more energy than a flat-mounted panel, and the gap widens at higher latitudes. Even a flat roof installation still captures 85 to 90 percent of optimal annual energy in most temperate locations.
Which direction should panels face in the southern hemisphere?
Panels in the southern hemisphere should face true north (not magnetic north). The mirror rule applies: at 33 degrees south in Sydney, tilt 33 degrees with the array pointing north. The sun tracks across the northern sky from a southern observer.
Why use seasonal adjustments at all?
The sun sits higher in summer (steeper noon angle) and lower in winter. A summer-flat tilt of latitude minus 15 catches the high sun, while a winter-steep tilt of latitude plus 15 catches the low sun. Two manual adjustments per year add roughly 4 to 8 percent annual yield versus a fixed tilt.
Sources
- NREL PVWatts Calculator (2026 release), tilt-yield sensitivity tables.
- U.S. Department of Energy, Solar Photovoltaic System Design Basics.
- NOAA Earth System Research Laboratory, solar declination data.
- IEC 61724-1, photovoltaic system performance monitoring standard.