Solar Panel Tilt Angle Calculator
Find the best tilt for your location for the whole year, for winter and for summer.
For a fixed array facing south, the best year-round tilt is a little less than your latitude. In Austin, at 30 degrees north, the tool gives 27 degrees. In Seattle, at 47.6 degrees, it gives 37. This calculator works the angle out for your area from sun data, so you don’t have to rely on a rule of thumb.
It also shows the best angles for winter and for summer, and what you lose at other angles. Add your roof pitch to see how it compares.
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Planning estimates only. Your roof, equipment, utility rules and weather change the real numbers, so get a written quote before you buy. Data as of October 2026.
How this calculator works
The tool runs the same sun model as the output calculator for every tilt from 0 to 90 degrees, facing true south, and picks the angle that makes the most energy. It repeats that for the winter months and for the summer months. The table shows how much of the best result you keep at other angles.
Most roofs aren’t far off. In Austin a 15-degree roof makes about 98% of what the best angle would. A flat mount at 0 degrees makes about 91%. So unless your roof is very steep or nearly flat, mount the panels flush and spend your time on shade and direction instead.
Changing the angle by season
Setting panels to a steeper angle in winter and a flatter one in summer makes a few percent more energy. That’s the most a manual change can give you. It can make sense on a ground mount you can reach. On a roof it rarely pays for the trips up the ladder.
True south and magnetic south
A compass points to magnetic south, which is not true south. In the lower 48 the two differ by up to about 15 degrees. Check the magnetic declination for your address, or use a phone app set to true north.
Where the numbers come from
- NASA POWER, daily data 2006–2025 at the center of each 3-digit ZIP area, data as of October 2026.
Questions
What is the best angle for solar panels?
For a fixed array facing true south, the whole-year angle shown above. It is usually a few degrees below your latitude, and further below it in cloudy northern places.
Is it worth changing the tilt with the seasons?
Usually not on a roof. The gain is a few percent. On a ground mount you can reach, it is a small bonus.
What if my roof faces east or west?
The panels still work. In Austin an east or west roof makes about 12% less than a south roof, so it is often still worth it. The Solar Panel Output Calculator shows the exact loss for your direction.
Should panels face true south?
In the northern hemisphere, yes, for the most energy over the year. A west-facing array can pay off if your utility charges much more for evening power.
What about a flat roof?
Flat roofs use racks, usually at 5 to 15 degrees, to keep wind load and row spacing down. The best energy angle is steeper, but the rows then need more room.
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