Tilt Angle
Tilt angle is the angle of solar panels measured from the horizontal plane, expressed in degrees. A tilt angle of 0° means panels are flat (horizontal); 90° means panels are completely vertical (like a wall-mounted installation).
The optimal tilt angle for a fixed solar array varies by latitude and season:
- For maximum annual production: Tilt ≈ site latitude. At latitude 35°N (e.g., Los Angeles, Memphis), a 35° tilt maximizes annual production.
- For maximum summer production: Tilt ≈ latitude − 15°. Lower tilt captures more summer sun when the sun is high in the sky.
- For maximum winter production: Tilt ≈ latitude + 15°. Steeper tilt captures more winter sun when the sun is lower.
Common Tilt Applications
Residential rooftop (sloped roof): Tilt is usually determined by the roof pitch, which typically ranges from 15° to 40°. Panels are mounted flush with the roof, so the tilt equals the roof pitch.
Commercial flat rooftop: Panels are mounted at 5–15° tilt using low-profile ballasted racking. Low tilt reduces wind loading while providing some self-cleaning benefit from rain and minimizing shading between rows.
Ground-mount (fixed-tilt): Typically 20–30° tilt, often close to site latitude, optimized for maximum annual production and minimum O&M.
Single-axis tracking: Tilt is variable — panels rotate around a north-south axis, tracking the sun from east in the morning to west in the afternoon, effectively varying effective tilt throughout the day.
In SolarScope
Enter your planned tilt angle in project settings. SolarScope uses the tilt angle to calculate the plane-of-array irradiance from horizontal GHI data, providing production estimates specific to your chosen orientation.