pvlib.solarposition.calc_time(lower_bound, upper_bound, latitude, longitude, attribute, value, altitude=0, pressure=101325, temperature=12, horizon='+0:00', xtol=1e-12)[source]#

Calculate the time between lower_bound and upper_bound where the attribute is equal to value. Uses PyEphem for solar position calculations.

  • lower_bound (datetime.datetime) –

  • upper_bound (datetime.datetime) –

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

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

  • attribute (str) – The attribute of a pyephem.Sun object that you want to solve for. Likely options are ‘alt’ and ‘az’ (which must be given in radians).

  • value (int or float) – The value of the attribute to solve for

  • altitude (float, default 0) – Distance above sea level.

  • pressure (int or float, optional, default 101325) – Air pressure in Pascals. Set to 0 for no atmospheric correction.

  • temperature (int or float, optional, default 12) – Air temperature in degrees C.

  • horizon (string, optional, default '+0:00') – arc degrees:arc minutes from geometrical horizon for sunrise and sunset, e.g., horizon=’+0:00’ to use sun center crossing the geometrical horizon to define sunrise and sunset, horizon=’-0:34’ for when the sun’s upper edge crosses the geometrical horizon

  • xtol (float, optional, default 1.0e-12) – The allowed error in the result from value



  • ValueError – If the value is not contained between the bounds.

  • AttributeError – If the given attribute is not an attribute of a PyEphem.Sun object.