solposx.solarposition.walraven

solposx.solarposition.walraven(times, latitude, longitude)

Calculate solar position using the Walraven algorithm.

Walraven’s algorithm [1] has a stated accuracy of 0.01 degrees. The implementation accounts for the 1979 Erratum [2] and the correct azimuth quadrant selection [3].

Parameters:

• times (pandas.DatetimeIndex) – Timestamps - must be localized. Prior to 1970 and far in the future UTC and UT1 may deviate significantly. For such use cases, UT1 times should be provided.

• latitude (float) – Latitude in decimal degrees. Positive north of equator, negative to south. [degrees]

• longitude (float) – Longitude in decimal degrees. Positive east of prime meridian, negative to west. [degrees]

Returns:

DataFrame with the following columns (all values in degrees):

• elevation : actual sun elevation (not accounting for refraction).

• zenith : actual sun zenith (not accounting for refraction).

• azimuth : sun azimuth, east of north.

Return type:

pandas.DataFrame

References

[1]

R. Walraven, “Calculating the position of the sun,” Solar Energy, vol. 20, no. 5, pp. 393–397, 1978, DOI: 10.1016/0038-092x(78)90155-x.

[2]

R. Walraven, “Erratum,” Solar Energy, vol. 22, pp. 195, 1979, DOI: 10.1016/0038-092X(79)90106-3

[3]

J. W. Spencer, “Comments on The Astronomical Almanac’s Algorithm for Approximate Solar Position (1950–2050),” Solar Energy, vol. 42, no. 4, pp. 353, 1989, DOI: 10.1016/0038-092x(89)90039-x.