The Short Answer
In the Northern Hemisphere (all of the U.S.), south-facing is ideal for maximum annual energy production. However, west-facing panels can be better if you have time-of-use (TOU) rates that charge more for afternoon/evening electricity. East-facing works but produces less. Avoid north-facing if possible.
| Direction | % of Optimal | Best For |
|---|---|---|
| South | 100% | Maximum total production |
| Southwest | 95-99% | Balance of production and TOU value |
| West | 85-95% | TOU rates, afternoon peak demand |
| Southeast | 92-97% | Morning production priority |
| East | 80-90% | Morning-heavy usage, no afternoon sun |
| North | 50-65% | Last resort only |
South-Facing: The Gold Standard
Why South is Best
In the Northern Hemisphere, the sun is always to the south of directly overhead. South-facing panels receive the most direct sunlight throughout the day:
- Morning sun hits at an angle, increasing through midday
- Peak production at solar noon (around 1 PM during daylight saving time)
- Afternoon sun decreases gradually
- Most total kWh produced over the year
Production Profile
South-facing panels produce a symmetric bell curve of power:
- 6-8 AM: Ramping up (10-30% of peak)
- 10 AM - 2 PM: Peak production (80-100%)
- 4-6 PM: Declining (30-60% of peak)
- After sunset: Zero production
When South is the Clear Winner
- Net metering with full retail credit (kWh produced = kWh credited)
- Flat-rate electricity (no time-of-use pricing)
- Maximum annual production is the goal
- No shading issues on south-facing roof
West-Facing: The TOU Champion
Why West Can Be Smarter
Many utilities now charge higher rates in the late afternoon and evening (4-9 PM) when grid demand peaks. West-facing panels produce more during these expensive hours:
| Time Period | South Production | West Production | TOU Rate (typical) |
|---|---|---|---|
| 10 AM - 12 PM | High | Moderate | Off-peak ($0.12) |
| 12 PM - 3 PM | Peak | High | Mid-peak ($0.18) |
| 3 PM - 6 PM | Declining | Peak | On-peak ($0.35) |
| 6 PM - 8 PM | Low | Moderate | On-peak ($0.35) |
When West Beats South
- Aggressive TOU rates: When peak rates are 2-3x off-peak rates
- NEM 3.0 in California: Export rates vary by time; afternoon exports worth more
- Self-consumption priority: If you're home in the evening and use power then
- No battery storage: West production aligns better with evening usage
East-Facing: Morning Production
When East Works
East-facing panels produce most of their energy in the morning:
- Peak production: 8 AM - 12 PM
- Declining: After noon, in shade from afternoon sun
- Total production: 80-90% of south-facing
East Makes Sense If:
- Your only viable roof space faces east
- West side has shade from trees or structures
- You have high morning electricity usage
- You pair east panels with west panels (split array)
East + West Combination
Some installers recommend splitting your array between east and west:
- Produces a flatter daily curve (good for self-consumption)
- Longer production window (sunrise to sunset)
- Total production is 85-95% of all-south
- Works well with TOU rates if west portion is larger
North-Facing: The Last Resort
Why North is Problematic
North-facing panels in the Northern Hemisphere face away from the sun:
- Never receive direct sunlight (only diffuse light)
- Produce only 50-65% of south-facing output
- Worst production in winter when sun is lowest
- May not be worth the installation cost
When North Might Still Work
- Low-slope roofs: Nearly flat roofs minimize the penalty
- Very high electric rates: Even reduced production saves money in CA, HI
- Large system needed: If you need more capacity than south/west can provide
- Environmental priority: Some production is better than none
Optimal Tilt Angle
The Basic Rule
The optimal tilt angle for fixed solar panels is approximately equal to your latitude:
| Location | Latitude | Optimal Tilt |
|---|---|---|
| Miami, FL | 25.8 | 20-26 |
| Los Angeles, CA | 34.1 | 30-34 |
| Denver, CO | 39.7 | 35-40 |
| New York, NY | 40.7 | 35-41 |
| Seattle, WA | 47.6 | 40-48 |
Real-World Tilt
Most residential roofs have a pitch between 15-45 degrees. The good news: tilt angle matters less than you might think:
- Being 10-15 from optimal tilt costs only 1-3% production
- Most roof pitches are close enough to optimal
- Flat roofs use tilted racking (adds cost but enables optimal angle)
- Steeper is better for self-cleaning (rain washes off dust)
Real-World Considerations
Shading Trumps Direction
A shaded south-facing roof produces less than an unshaded west-facing roof. Consider:
- Trees (current and future growth)
- Neighboring buildings
- Chimneys, vents, and dormers
- Seasonal sun angle changes
Roof Space and Aesthetics
Sometimes practical factors override theoretical optimization:
- Available roof space may dictate placement
- Street-facing aesthetics matter to some homeowners
- HOA rules may restrict visible panels
- Fire setbacks reduce usable space
Microinverters and Optimizers
Modern panel-level electronics (microinverters or DC optimizers) help maximize production from less-than-ideal orientations:
- Each panel operates independently
- Partial shading doesn't affect entire array
- Mixed orientations work better (east + west, south + west)
- Slightly higher cost but better overall performance
Which Direction is Best for Your Roof?
Tell us about your roof orientation, shading, and utility rates, and we'll help you understand your best options.
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