Precise North - Solar Compass

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About this app

This application uses high precision algorithms for the calculation of the sun position (error <0.01°). No magnetic compass is needed. With the help of the sun shadow the precise North/South orientation can be determined. The implemented sun position algorithm is valid until the year 2050. An overall precision of better than 0.5 degree can be achieved. The algorithm uses local coordinates (latitude and longitude) and the exact time (UTC), which both can be retrieved comfortably via the built-in GPS.

The application is especially useful to orientate concentrating solar energy systems, which need an exact North/South or East/West alignment. This can be the case for fresnell or parabolic troughs as well as for concentrating systems, which are tracked around the polar axis as for example fix focus Scheffler reflectors from Simply Solar ( The only condition is, that the measurement has to be performed under sunny conditions.

The red line indicated on the phone display must be aligned with the shadow line of a nearby, vertical obstacle or a cord of a pendulum. Once aligned with the shadow line, your phone will point exactly in North/South direction. You can check with the built in sensor, if the phone is placed horizontally and if the obstacle has a vertical 90° edge.

At solar noon the App will emit an acoustic alarm, which informs you, that the current shadow line points exactly in north south direction.

You can further use the application to control the polar axis inclination angle (latitude angle).
An easy understandable sensor calibration menu helps to get as exact measurements as possible.
Updated on
Oct 8, 2014

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