Sun Position and Solar Panel Tilt Calculator

What the sun angles tell you

The sun's place in the sky is described by two angles. The elevation angle is how high the sun stands above the horizontal plane, and the azimuth is its direction, measured clockwise from true north. In the Northern Hemisphere the sun is due south and at its highest at local solar noon. Sunrise and sunset directions shift with the seasons: in summer the sun rises in the north-east and sets in the north-west, in winter it rises in the south-east and sets in the south-west. The chart in the tool plots the selected day's elevation curve together with the curves for 21 June and 21 December, so you can compare the highest and lowest sun conditions of a site at a glance.

How to choose the solar panel tilt angle

A fixed-tilt panel faces true south in the Northern Hemisphere and true north in the Southern Hemisphere. If you align it with a compass, correct the reading for magnetic declination; the Magnetic Declination Calculator does this for you.

For a fixed annual tilt the tool shows two published approximate methods:

• Jacobson and Jadhav (2018): the authors used the US National Renewable Energy Laboratory's PVWatts program to find optimal tilts for locations in every country and fitted a third-order polynomial in latitude. For the Northern Hemisphere, tilt = 1.3793 + φ(1.2011 + φ(−0.014404 + φ·0.000080509)). The study shows that at cloudy and hazy high latitudes the optimal tilt stays well below the latitude. The formula gives about 31.5° at 40° latitude.
• Landau: for latitudes between 25° and 50°, annual tilt = latitude × 0.76 + 3.1°. The same source gives a two-season adjustment with a summer angle of latitude × 0.93 − 21° and a winter angle of latitude × 0.875 + 19.2°, switching to the summer angle on 30 March and to the winter angle on 10 September. The tool also shows its four-season coefficients.

Both methods are approximations. The final tilt and row layout should come from an energy yield simulation that uses site-specific hourly irradiance, cloud cover, ground reflectance (albedo), surrounding shading and temperature losses. For the criteria to consider when choosing land, see our guide how to choose land for a solar power plant (in Turkish), and our renewable energy sector page.

Calculating shadow length

On level ground the shadow of an object of height h is L = h / tan(α), where α is the solar elevation angle. With the sun 30° high the shadow is about 1.73 times the object's height, and at 45° it equals the height. The shadow points in the direction opposite the sun. The tool gives the shadow length and direction for the selected moment and the shadow length at noon on the winter solstice. That moment, when the sun is at its lowest of the year, is a common starting point for assessing shading from panel rows, buildings and trees. On sloping ground the shadow becomes longer or shorter depending on the direction of the slope.

How to use it

1. Tap a point on the map or enter latitude and longitude in decimal degrees.
2. Choose the date and local time and change the time zone if needed. The "Now" button uses your device clock.
3. Enter the height of the object whose shadow you want to know, in metres.
4. The results list the sun angles, sunrise and sunset times and directions and the shadow values; the section below shows the panel tilt suggestions and the angle of incidence on the panel. Lines on the map show the sunrise, sunset, current sun and shadow directions.

Data and method

The sun position is calculated with the equations used in the solar calculator of the US National Oceanic and Atmospheric Administration's Global Monitoring Laboratory (NOAA GML), which are based on Jean Meeus's "Astronomical Algorithms"; NOAA's atmospheric refraction correction is applied to the elevation angle. Sunrise and sunset are defined as the moment the centre of the sun is 0.833° below the horizon. NOAA states that with this method sunrise and sunset times are theoretically accurate to within a minute between ±72° latitude. The method is valid for the years 1901 to 2099. Icons come from Lucide (ISC licence); the chart is drawn as plain SVG without a charting library, and the basemaps are provided by Esri and OpenStreetMap contributors. All calculations run in your browser and your location is not sent to any server. Open-source libraries used and their licences: Data Sources.