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.
Last updated: September 2026
Formula below · 2 sources (nrel.gov, Wikipedia) · Updated Sep 2026
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About this calculator
The best fixed tilt for a solar panel depends mainly on latitude, because the sun's noon elevation averages 90° − latitude over the year. This calculator uses Charles Landau's fitted rules (solarpaneltilt.com), derived from year-round insolation modelling for latitudes of about 25–50°: year-round tilt = |latitude| × 0.76 + 3.1°; summer-optimized (twice-yearly adjustment) = |latitude| × 0.93 − 21°; winter-optimized = |latitude| × 0.875 + 19.2°. Summer tilts are shallower because the summer sun is high; winter tilts are steeper to face the low winter sun. The mount type changes what you can actually do: an adjustable or fixed tilt rack is set to the recommended angle (an adjustable mount lets you switch between the summer and winter values), while a flush roof mount simply follows the roof, so for that option the result is your roof pitch — compare it with the year-round value to see how far off the roof is. Results are clamped between 0° and 90°. Outside 25–50° latitude treat the result as a rough guide.
How to use
Suppose you live at latitude 40°N. Year-round on a fixed tilt rack: 40 × 0.76 + 3.1 = 33.5°. Winter-optimized on an adjustable mount: 40 × 0.875 + 19.2 = 54.2°. Summer-optimized: 40 × 0.93 − 21 = 16.2°. If instead the panels are flush-mounted on a 20° roof, the result is simply 20° — about 13.5° flatter than the 33.5° year-round optimum, which typically costs only a few percent of annual output.
Frequently asked questions
What is the best solar panel angle for my latitude?
A good year-round rule for latitudes of about 25–50° is to multiply your latitude by 0.76 and add 3.1° (Landau). At 35°N that gives about 29.7°, and at 45°N about 37.3° — a little flatter than the "tilt equals latitude" rule, because the long summer days carry more energy. If you can adjust the panels twice a year, use about latitude × 0.93 − 21° in summer and latitude × 0.875 + 19.2° in winter.
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 (about latitude × 0.93 − 21°) keeps them more perpendicular to the high midday sun. Steepening the tilt in winter (about latitude × 0.875 + 19.2°) catches the low-angle rays more directly, boosting output during short days. If you can only set one fixed angle, the year-round value (latitude × 0.76 + 3.1°) minimizes losses across all months.
Does roof pitch affect the optimal solar panel angle?
Only for flush mounts. When panels are flush-mounted on a roof, the roof pitch becomes the tilt and cannot be changed, so with the Flush Roof Mount option the calculator returns the roof pitch; compare it with the year-round optimum to see how much you give up. The closer your roof pitch already is to the optimum, the less production you sacrifice. If the gap is large, tilt racks or ground mounts can recover much of the lost output.