The direction solar panels face significantly influences their energy production because it affects the amount and intensity of sunlight they receive throughout the day.
Optimal Direction for Solar Panels
- Northern Hemisphere (e.g., U.S., Canada, Europe):
Solar panels should ideally face true south (geographic south, not magnetic south) to receive the most direct sunlight over the course of the day. This orientation maximizes exposure to the sun as it moves across the southern part of the sky, leading to the highest energy output. - Southern Hemisphere:
Panels should face true north for the same reason, to capture maximum sunlight.
Impact of Facing Directions Other than South
- Facing panels away from true south reduces energy output, with the degree of loss dependent on orientation:
- Slightly southeast or southwest: about 8% reduction in output compared to south-facing panels.
- Facing east or west: approximately 15% less energy production than south-facing panels.
- Facing north (opposite to optimal direction in northern hemisphere): can result in about 30% less energy production, making it the least effective direction.
- Despite reduced output, east or west-facing panels can still be viable options if south-facing roof space is limited or unavailable, often providing adequate power generation.
Time-of-Use (TOU) Pricing Considerations
- In regions with Time-of-Use electricity pricing, where electricity is more expensive during peak evening hours, orienting panels toward the southwest or west can be advantageous. This shifts power production to later in the day when electricity demand and rates are higher, potentially lowering energy costs despite a slight reduction in total annual energy production.
- East-facing panels receive more morning sunlight but generally produce less energy than south-facing panels, and are usually considered only when no other options exist.
Why Direction Matters
- Solar panels generate the most power when the sun’s rays strike them perpendicularly. Panels facing the sun more directly absorb more energy, as photovoltaic cells are more efficient at converting sunlight to electricity when light hits them head-on.
- Even a small deviation from true south can reduce energy capture, but minor offsets (e.g., 10 degrees) typically reduce production by less than 1% annually, making near-south orientations still effective.
Summary Table of Solar Panel Direction Effect on Output (Northern Hemisphere)
| Panel Direction | Approximate Energy Output Compared to True South | Approximate Output Reduction |
|---|---|---|
| True South | 100% | 0% |
| Southeast / Southwest | 92% | ~8% |
| East / West | 85% | ~15% |
| North | 70% | ~30% |
Additional Notes
- The solar panel tilt angle should generally be set close to the geographical latitude for optimal annual energy production, complementing the directional orientation.
- Fixed panels without tracking systems rely heavily on correct orientation and tilt to maximize output, while systems with solar tracking can adjust to follow the sun, significantly increasing energy capture but at higher cost and complexity.
- Local factors such as shading, roof size, and local climate can also influence the effective direction choice and system design.
In conclusion, for maximum energy production, solar panels in the northern hemisphere should face true south at an angle close to the latitude. Deviations from this direction reduce energy output, with north-facing panels performing worst. However, adjustments toward southwest or west can improve energy availability during peak evening demand in areas with TOU pricing. Panels facing east or west still produce substantial energy and can be practical alternatives depending on roof orientation and site conditions.
Original article by NenPower, If reposted, please credit the source: https://nenpower.com/blog/how-does-the-direction-of-solar-panels-affect-their-energy-production/
