Best tilt and orientation for solar panels

Solar panels produce the most when sunlight hits them head-on. Because the sun moves across the sky during the day and changes height through the year, no fixed angle is perfect all the time. But one angle and direction gives the most energy over the whole year, and it is easy to estimate.

Why tilt matters

The sun is high in summer and low in winter. A flat panel catches the high summer sun well but the low winter sun poorly. A steep panel is the opposite. The best fixed tilt is a compromise weighted towards summer, when there is much more sunlight to collect.

Weather shifts the ideal. In a sunny climate most energy arrives as direct sunlight, and slightly steeper panels are best. In a cloudy climate a large share arrives as diffuse light from the whole sky, which favours flatter panels that “see” more sky. That is why real-world optimum tilts, which include weather, are often 5° to 10° flatter than the clear-sky optimum.

Why direction matters

A panel facing due south (in the Northern Hemisphere) sees the sun head-on at solar noon, when it is highest and strongest. Turning the panel east shifts its best hours to the morning; turning it west shifts them to the afternoon.

The loss grows slowly at first. At a moderate tilt:

• south-east or south-west (±45°): usually about 5% to 8% less over the year,
• due east or west (±90°): usually about 15% to 25% less,
• due north at 30° tilt: about 35% to 45% less at mid-latitudes, and much worse for steeper panels.

The flatter the panel, the less direction matters. At 10° tilt even an east-facing roof loses only a few percent.

East-west systems

Many flat-roof installations put panels in east-west rows at a low tilt of 10° to 15°. Each panel produces less than a south-facing one, but you can fit more panels on the roof, and production is spread from early morning to evening, which matches household use better. When self-consumption matters more than peak output, east-west can be the better choice.

Vertical panels and balconies

Vertical panels on a south-facing balcony or facade produce about 25% to 35% less per year than well-tilted roof panels at mid-latitudes, but they do relatively well in winter, when the sun is low, and they shed snow. For balcony solar kits they are often the only option, and still worthwhile.

Try your roof

The solar panel angle calculator finds the best tilt and direction for your exact location, shows how much of the maximum your roof reaches, and compares every combination of tilt and direction in one table. Its numbers use typical weather for your latitude and no shading, which is enough for comparing angles. For a production estimate based on local weather records, use a tool such as the European Commission’s free PVGIS.