Roof Pitch
Angle of the roof relative to the horizontal -- affects solar yield and optimal module orientation.
Also known as: Tilt Angle, Roof Angle
What Is Roof Pitch?
Roof pitch describes the angle between the roof surface and the horizontal plane, given in degrees (°). It significantly determines how much sunlight the solar modules capture throughout the year and is an important factor for yield planning.
Optimal Roof Pitch for PV
| Goal | Optimal Tilt | Orientation |
|---|---|---|
| Maximum annual yield | 30—35° | South |
| Maximum summer yield | 20—25° | South |
| Maximum winter yield | 55—60° | South |
| Self-consumption optimised | 30—40° | East-West |
Yield Losses from Deviation
Photovoltaics is remarkably tolerant of deviations from the optimum:
| Roof Pitch | Yield (relative, south-facing) |
|---|---|
| 0° (flat) | approx. 87% |
| 15° | approx. 95% |
| 30° | approx. 100% (optimum) |
| 45° | approx. 97% |
| 60° | approx. 90% |
| 90° (facade) | approx. 70% |
Typical Roof Pitches in Germany
- Flat roof: 0—5° (tilt mounting recommended)
- Mono-pitch roof: 5—15°
- Gable roof: 20—50° (usually 35—45°)
- Hip roof: 25—40°
Practical Tip
Most German gable roofs have a pitch of 35—45° and are therefore nearly optimal for photovoltaics. Even with an unfavourable pitch or orientation, PV is worthwhile in most cases.
Related Terms
Azimuth
Compass direction of the module orientation in degrees -- 0° = South, -90° = East, +90° = West, +/-180° = North.
Tilt Mounting
Mounting system that positions solar modules at an optimal tilt angle on flat roofs or open ground.
Global Irradiance
Total solar radiation hitting a horizontal surface -- the sum of direct and diffuse radiation.
PVGIS
Free EU online tool for calculating solar yields based on location, orientation, and tilt angle.