The single most important decision in a solar PV installation after system sizing is panel orientation and tilt. Getting the angle right can mean the difference between a system that meets your energy needs and one that significantly underperforms. The general rule is simple: optimal fixed tilt ≈ your latitude.
Optimal Tilt by Latitude
The table below gives the optimal fixed tilt angle for any latitude, along with recommended adjustments for summer and winter to capture additional seasonal yield. These values assume a south-facing orientation in the northern hemisphere.
| Latitude | Optimal Fixed Tilt | Summer Tilt (Apr-Sep) | Winter Tilt (Oct-Mar) |
|---|---|---|---|
| 0° (Equator) | 0° (flat) | 0° | 15° |
| 10° | 10° | 0° | 25° |
| 20° | 20° | 5° | 35° |
| 30° | 30° | 15° | 45° |
| 40° | 40° | 25° | 55° |
| 50° | 50° | 35° | 65° |
How to read this table: If you live at 35° latitude (e.g., Tokyo, Los Angeles, Casablanca), your optimal fixed tilt is 35°. For a summer optimised array, tilt to 20°; for winter, tilt to 50°. Seasonal adjustment requires adjustable mounting hardware.
Azimuth: Which Direction Should Panels Face?
Azimuth is the compass direction your panels face. The rule depends on your hemisphere:
- Northern hemisphere: Face panels toward True South (180°). Magnetic declination varies by location, so use True South (south as shown on a map, not a magnetic compass).
- Southern hemisphere: Face panels toward True North (0°).
- At the equator (0° latitude): Panels can be mounted flat (0° tilt) with negligible directional preference. East-west orientations are common for space-constrained roofs.
Yield Loss for Suboptimal Orientation
Not every roof faces the ideal direction. The table below shows the approximate annual energy loss for common suboptimal orientations (assuming 40° latitude, optimal tilt):
| Orientation | Annual Yield Loss vs Optimal | Typical Scenario |
|---|---|---|
| South (optimal) | 0% | Ideal south-facing roof |
| Southeast / Southwest | 5% | Common on standard rectangular roofs |
| East / West | 15% | Side-facing roofs, townhouses |
| North (northern hemisphere) | 30% | North-facing roof only option |
Losses are smaller at lower latitudes. At 20° latitude, an east-west orientation loses only about 8-10% compared to a south-facing array. At 50° latitude, the same east-west orientation can lose 18-20%.
Seasonal Tilt Adjustment
If you can adjust your panel tilt twice a year, you can capture 5-10% more annual yield compared to a fixed tilt system. The adjustment is simple:
- Summer (April - September): Tilt = Latitude minus 15° (minimum 0°). This captures the high summer sun.
- Winter (October - March): Tilt = Latitude plus 15° (maximum 65°). This tilts panels steeper to catch the low winter sun.
Optimal Winter Tilt = min(Latitude + 15°, 65°)
Adjustable tilt mounts add upfront cost ($200-500 for a residential system) but the 5-10% yield improvement often pays for itself within 2-4 years, especially at higher latitudes where seasonal variation is greatest.
Flat Roofs and East-West Arrays
Flat roofs are actually excellent for solar. Panels can be tilted at the optimal angle using racks. A common approach on flat commercial roofs is the east-west array where half the panels face east and half face west. This reduces peak power output but extends the generation window across the day. For a home with net metering, the annual yield is only about 5% lower than a south-facing array, but self-consumption rates improve significantly.
Related Guides
- How Location Affects Solar Panel Performance
- Solar Panel Performance in Winter vs Summer
- Monthly Bill to kWp Conversion
Optimise your panel angle for your location
Open the Solar Calculator →Data sources: NREL PVWatts v8, European Commission JRC PVGIS 5.2, NASA POWER. Yield loss percentages are approximate and vary by latitude, local climate, and specific system configuration. Seasonal adjustment estimates assume two adjustments per year with optimal hand-tuning.
Last updated: July 2026 | Browse all guides