Solar Panel Tilt Angle Calculator

How it is calculated

The tool uses a simple rule of thumb based on the absolute value of latitude, so 40 and −40 give the same tilt. Year-round: tilt = |latitude|. Winter: tilt = |latitude| + 15. Summer: tilt = |latitude| − 15. The result is kept between 0° and 90°, so near the equator a summer tilt is shown as 0.0° (flat), and at high latitudes a winter tilt stops at 90.0° (vertical). The season is applied as chosen, with no swap for the southern hemisphere, so pick the season in terms of the sun's height at your site. Any other or missing season is treated as year-round. Latitude must be between −90 and 90, in decimal degrees; a value outside that range shows no result. The tilt is measured from horizontal. A positive latitude gets the advice to face the panels true south, a negative one true north, and 0 the equator note. It is a general guide, not a simulation of local weather or shading.

Common mistakes

• Entering a latitude in degrees-minutes-seconds (such as 40°42′) as 40.42. The field takes decimal degrees, so convert first: 40°42′ is 40.7.
• Entering longitude instead of latitude. Only latitude matters here, and a longitude above 90 returns no result.
• Dropping the minus sign for a southern site. Tilt uses the absolute value, so the angle is the same, but without the sign the tool tells you to face the panels south instead of true north.
• Treating the tilt as an angle from vertical. It is measured from the horizontal, with 0° lying flat and 90° upright.
• Using the seasonal values for a roof that cannot be adjusted. A fixed array has one angle, so choose year-round unless your demand is concentrated in one season. Also expect the summer value to be flat (0.0°) at latitudes below 15°.