Optimal orientation and tilt for solar panels

Solar optimum is like true north on a compass: it exists, but few roofs respect it 100%. What matters isn't being perfect, but knowing how much you lose per deviation. Here's the table installers use.

Azimuth (orientation)

In the northern hemisphere, true south = 0°. Each degree of deviation costs annual yield, but less than people think:

• True south (0°): 100% of optimum
• Southeast or southwest (±30°): 97-98%
• Pure east or west (±90°): 80-85%
• Pure north: 40-55% (don't bother)

Tilt

Optimal tilt depends on your latitude. Quick rule: latitude ± 5°. In the southern US (~30°N), 25-32°. For winter-priority loads, add 10-15°. For summer-priority (pool), subtract 10-15°.

• Flat roof (0°): 12-15% annual loss vs optimum
• 10° tilt: 6-8% loss
• 20°: 2-3% loss
• 30-35°: optimal for latitudes 35-45°N
• 45°: 2-4% loss (better in winter)
• 60°: 8-12% loss (winter only)

Real combinations

East-west gable roof at 30° tilt: ~90% of optimum but with a very flat production curve (good morning and afternoon). Ideal if your usage is mostly daytime. Flat roof: add tilted racking or lay them nearly flat to reduce wind loads.

When tracking does NOT pay off

Solar trackers boost output 15-25% but their cost and maintenance only justify themselves at utility scale. For residential, fixed mounts are the answer.

If your roof is flat, see flat roof vs pitched roof solar. If you have shading, see how shading hurts solar output.