The year-round rule is simple: tilt the panels at about your latitude and face them due south. The month-by-month tilt follows the sun, which climbs higher in summer and sinks in winter; it uses the standard formula for the sun's declination.
How to use this calculator
- Enter your latitude in degrees north. Your phone's map app shows it, or look up your town.
- Read the best fixed tilt. If your mount can be adjusted, use the summer and winter tilts or the monthly table.
- Measure the tilt up from flat with an angle finder, and face the panels true south.
Worked examples
Miami
Latitude: 25.8 °
- Best fixed tilt, all year
- 25.8°
- Summer tilt
- 10.8°
- Winter tilt
- 40.8°
- As a roof pitch
- 5.8 in 12
Phoenix
Latitude: 33.4 °
- Best fixed tilt, all year
- 33.4°
- Summer tilt
- 18.4°
- Winter tilt
- 48.4°
- As a roof pitch
- 7.9 in 12
Denver
Latitude: 39.7 °
- Best fixed tilt, all year
- 39.7°
- Summer tilt
- 24.7°
- Winter tilt
- 54.7°
- As a roof pitch
- 10.0 in 12
Minneapolis
Latitude: 45 °
- Best fixed tilt, all year
- 45.0°
- Summer tilt
- 30.0°
- Winter tilt
- 60.0°
- As a roof pitch
- 12.0 in 12
Anchorage
Latitude: 61.2 °
- Best fixed tilt, all year
- 61.2°
- Summer tilt
- 46.2°
- Winter tilt
- 76.2°
- As a roof pitch
- 21.8 in 12
The best fixed tilt
The US Department of Energy puts it plainly: for the most energy over a year, point the panels due south and tilt them at an angle equal to your latitude. Steeper favors winter, flatter favors summer.
In cloudy or coastal places a slightly flatter tilt can do better, because diffuse light comes from the whole sky: a study of US sites found the best tilt up to 10 degrees below the latitude, never above it.
Adjusting with the seasons
The sun's path moves by 23.45 degrees either side of the equator over the year, so the best tilt moves too: up to 15 degrees from the latitude, steeper in winter and flatter in summer. That is where the summer and winter tilts come from.
The gain is real but modest. Across many US sites, changing the tilt every month added about 5 percent a year over the best single tilt; in sunny Tucson, two changes a year added about 7.59 percent. For most rooftop systems a fixed tilt is fine.
Which way to face the panels
Due south, measured from true south rather than a compass reading, which is off by the local magnetic declination. Panels facing southeast or southwest make roughly 5 to 10 percent less energy, and one Oregon example facing due west made about 88 percent of what south-facing panels did.
Common questions
What angle should my solar panels be at?
About equal to your latitude for the most energy over a year, facing due south. Enter your latitude above to see the year-round, summer and winter tilts.
How do I measure the tilt angle of a solar panel?
Set an angle finder or a phone level app on the panel frame: the tilt is the angle up from flat. On a roof, the roof pitch sets it, and the calculator shows the tilt as a pitch too.
Is it worth adjusting solar panels for the seasons?
Sometimes. Monthly changes added about 5 percent a year on average across US sites, and two changes a year about 7.59 percent in Tucson. On a ground mount that is easy to adjust it can pay off; on a roof, a fixed tilt is usually fine.
Do solar panels have to face south?
South is best in the US. Southeast or southwest costs roughly 5 to 10 percent of the energy, and east or west more.
What is the best angle for solar panels in winter?
Steeper than your latitude, by up to 15 degrees, because the winter sun is low. The winter tilt above shows it, and the monthly table gives each month.