What is the best roof pitch for solar panels?
Why latitude sets the ideal
For a fixed array, the angle that captures the most sun over a full year is roughly equal to your latitude. Georgia runs from about 30 to 35 degrees north, and Atlanta is near 34. A 7:12 pitch is about 30 degrees and an 8:12 pitch about 34, which is why those slopes are close to ideal here.
Why most pitches are fine
The output curve is fairly flat near the ideal. A 4:12 or 5:12 roof gives up only a modest share of annual production, and lower angles actually do better in summer when the sun is high. Very steep roofs above about 12:12 are harder and costlier to install on, and very low slopes may use tilted racks.
What matters more than pitch
- Direction. South-facing roofs produce the most. East and west faces produce noticeably less but can still be worthwhile. North faces are usually poor in Georgia.
- Shade. Pines and hardwoods can cut output dramatically, especially in the morning and late afternoon.
- Roof condition. Panels stay up for 25 years or more, so the roof under them should be new or close to it.
- Obstructions. Vents, chimneys and dormers break up usable area.
Check your own roof
NREL's free PVWatts calculator lets you enter your address, tilt and direction to estimate production. To convert pitch, the angle is the arctangent of rise over run. Before signing a solar contract, read replacing your roof before solar.