Solar Panel Angle Calculator
Find the ideal tilt angle for your solar panels based on your latitude, season, and roof pitch. Use this when installing or adjusting panels to maximize annual or seasonal energy capture.
About this calculator
The optimal solar panel tilt angle depends primarily on your geographic latitude, since the sun's elevation arc changes with distance from the equator. A widely used approximation scales latitude by 0.89 and then adjusts for seasonal sun position: panels tilted steeper in winter capture more of the lower winter sun, while a shallower summer tilt tracks the high summer arc. The core formula is: optimal angle = |latitude| × 0.89 + seasonal adjustment, where the seasonal offset is +15° for summer optimization, −15° for winter optimization, and 0° for year-round balance. If your panels are fixed to a roof rather than on an adjustable mount, the existing roof pitch is folded in, since you cannot independently set the panel angle. The result is clamped between 0° and 90° to remain physically meaningful.
How to use
Suppose you live at latitude 40°N and want to optimize for winter output, with a fixed roof mount at a 20° pitch. Step 1 — multiply latitude by 0.89: 40 × 0.89 = 35.6°. Step 2 — apply the winter seasonal adjustment: 35.6 + (−15) = 20.6°. Step 3 — since the mount is fixed (not adjustable), add the roof pitch: 20.6 + 20 = 40.6°. Your recommended winter tilt is approximately 41°. For a year-round, adjustable mount at the same latitude, the result would simply be 35.6°.
Frequently asked questions
What is the best solar panel angle for my latitude?
A good starting rule is to tilt your panels at roughly 0.89 times your latitude in degrees. At 35°N that gives about 31°, while at 55°N the baseline rises to roughly 49°. Seasonal adjustments of ±15° can further boost output when you need to favor summer or winter production. Fixed installations typically compromise with a year-round angle, whereas adjustable mounts allow seasonal repositioning for meaningful gains.
How does seasonal optimization affect solar panel tilt angle?
The sun traces a higher arc across the sky in summer and a lower arc in winter. Tilting panels shallower in summer (adding +15° to the base angle) keeps them more perpendicular to the intense midday sun. Steepening the tilt in winter (subtracting 15°) catches the lower-angle rays more directly, boosting output during shorter days. If you can only set one fixed angle, a year-round neutral tilt with no seasonal offset typically minimizes losses across all months.
Does roof pitch affect the optimal solar panel angle?
Yes — when panels are flush-mounted on a roof, the roof pitch becomes the effective tilt angle and cannot be changed independently. In that case the calculator adds the existing roof slope to the latitude-based optimal angle to show how far your actual installation deviates from the ideal. The closer your roof pitch already is to the calculated optimal, the less production you sacrifice with a fixed mount. If the gap is large, ballasted ground mounts or tilted racking systems can recover much of that lost efficiency.