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Solar Panel Tilt Angle Calculator

Work out solar panel tilt angle instantly with clear inputs, formula shown and shareable results.

About Solar Panel Tilt Angle Calculator

The rule of thumb for fixed panels is a tilt of about 0.9 times latitude for year-round output, reduced by roughly 23 degrees for summer and increased by about 29 degrees for winter. At 45 degrees latitude that means 40.5 degrees annually, 17 degrees for summer and 69.5 degrees for winter. Seasonal adjustment typically gains 5-10% over a fixed angle.

Formulas

Annual optimum

tilt = 0.9 x latitude

Seasonal adjustment

summer: 0.9 x latitude - 23.5; winter: 0.9 x latitude + 29

Worked example

With the default values below, Solar Panel Tilt Angle Calculator returns Recommended Tilt Angle of 40.5. Change any input above and every figure here is recalculated in your browser.

Inputs used

Site latitudeaccepts -66–66 deg
45 deg
Optimise forone of Year-round average, Summer output, Winter output
Year-round average

Results

Recommended Tilt Angle
40.5 deg
Year-Round Optimum
40.5 deg
Summer Optimum
17.0 deg
Winter Optimum
69.5 deg

Step by step

  1. 1Values used
  2. 2Annual optimum
  3. 3Seasonal adjustment
  4. 4Recommended Tilt Angle= 40.5 deg
  5. 5Year-Round Optimum= 40.5 deg
  6. 6Summer Optimum= 17.0 deg
  7. 7Winter Optimum= 69.5 deg

Assumptions and limits

  • The result is derived only from the 2 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 1 decimal place, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Is exact tilt critical?

No - output changes only a few percent within 10 degrees of optimum, which is why roof pitch is usually accepted as-is.

Why is the winter adjustment larger than the summer one?

Because winter sun is low and days are short, so the steeper angle also sheds snow and captures more of a weaker resource.

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