🧭 Solar Panel Tilt Angle

Written and maintained by the PhDino author · Last reviewed 21 September 2026 · A documented rule of thumb, pinned by automated tests · how PhDino checks its numbers

A latitude-based rule of thumb for angling a fixed solar panel toward the sun.

A fixed (non-tracking) solar panel performs best when it sits roughly perpendicular to the sun's rays — but since the sun's position in the sky changes throughout the day and across seasons, no fixed angle is ever perfectly aimed at every moment. The well-known starting rule of thumb is that a panel tilted to match the site's latitude captures a good year-round average, because that angle roughly bisects the sun's seasonal swing in altitude.

A site further from the equator has a lower sun in the sky on average, and needs a steeper panel tilt to face it — which is exactly why the optimal tilt tracks latitude directly. A system optimized to favor winter production (when the sun sits lowest and days are shortest, often the season generation is most needed) tilts steeper than latitude; one favoring summer tilts shallower.

Key formula

Year-round tilt ≈ latitude
Winter-biased tilt ≈ latitude + 15°
Summer-biased tilt ≈ latitude − 15°
Equinox solar noon sun angle = 90° − latitude

Notes & limitations

• This gives a starting angle, not a fully optimized one — real optimal tilt also depends on local cloud patterns and typical seasonal weather, which a pure latitude formula can't capture. Serious installations often check tilt against modeled local irradiance data rather than the rule of thumb alone.
• Peak sun hours (used in Solar Array Sizing) depend on local weather and climate, not just latitude and tilt — a cloudy coastal city and a sunny inland desert at the same latitude can have very different real-world sun hours despite an identical "optimal" tilt angle.