def solar_irradiation(latitude, longitude, Z, moment, surface_tilt,
surface_azimuth, T=None, P=None, solar_constant=1366.1,
atmos_refract=0.5667, albedo=0.25, linke_turbidity=None,
extraradiation_method='spencer',
airmass_model='kastenyoung1989',
cache=None):
r'''Calculates the amount of solar radiation and radiation reflected back
the atmosphere which hits a surface at a specified tilt, and facing a
specified azimuth.
This functions is a wrapper for the incredibly
comprehensive `pvlib library <https://github.com/pvlib/pvlib-python>`_,
and requires it to be installed.
Parameters
----------
latitude : float
Latitude, between -90 and 90 [degrees]
longitude : float
Longitude, between -180 and 180, [degrees]
Z : float, optional
Elevation above sea level for the position, [m]
moment : datetime, optionally with pytz info
Time and date for the calculation, in UTC time OR in the time zone
of the latitude/longitude specified BUT WITH A TZINFO ATTATCHED!
Please be careful with this argument, time zones are confusing. [-]
surface_tilt : float
The angle above the horizontal of the object being hit by radiation,
[degrees]
surface_azimuth : float
The angle the object is facing (positive, North eastwards 0° to 360°),
[degrees]
T : float, optional
Temperature of atmosphere at ground level, [K]
P : float, optional
Pressure of atmosphere at ground level, [Pa]
solar_constant : float, optional
The amount of solar radiation which reaches earth's disk (at a
standardized distance of 1 AU); this constant is independent of
activity or conditions on earth, but will vary throughout the sun's
lifetime and may increase or decrease slightly due to solar activity,
[W/m^2]
atmos_refract : float, optional
Atmospheric refractivity at sunrise/sunset (0.5667 deg is an often used
value; this varies substantially and has an impact of a few minutes on
when sunrise and sunset is), [degrees]
albedo : float, optional
The average amount of reflection of the terrain surrounding the object
at quite a distance; this impacts how much sunlight reflected off the
ground, gets reflected back off clouds, [-]
linke_turbidity : float, optional
The amount of pollution/water in the sky versus a perfect clear sky;
If not specified, this will be retrieved from a historical grid;
typical values are 3 for cloudy, and 7 for severe pollution around a
city, [-]
extraradiation_method : str, optional
The specified method to calculate the effect of earth's position on the
amount of radiation which reaches earth according to the methods
available in the `pvlib` library, [-]
airmass_model : str, optional
The specified method to calculate the amount of air the sunlight
needs to travel through to reach the earth according to the methods
available in the `pvlib` library, [-]
cache : dict, optional
Dictionary to to check for values to use to skip some calculations;
`apparent_zenith`, `zenith`, `azimuth` supported, [-]
Returns
-------
poa_global : float
The total irradiance in the plane of the surface, [W/m^2]
poa_direct : float
The total beam irradiance in the plane of the surface, [W/m^2]
poa_diffuse : float
The total diffuse irradiance in the plane of the surface, [W/m^2]
poa_sky_diffuse : float
The sky component of the diffuse irradiance, excluding the impact
from the ground, [W/m^2]
poa_ground_diffuse : float
The ground-sky diffuse irradiance component, [W/m^2]
Examples
--------
>>> import pytz
>>> solar_irradiation(Z=1100.0, latitude=51.0486, longitude=-114.07, linke_turbidity=3,
... moment=pytz.timezone('America/Edmonton').localize(datetime(2018, 4, 15, 13, 43, 5)), surface_tilt=41.0,
... surface_azimuth=180.0)
(1065.7621896280, 945.2656564506, 120.49653317744, 95.31535344213, 25.181179735317)
>>> cache = {'apparent_zenith': 41.099082295767545, 'zenith': 41.11285376417578, 'azimuth': 182.5631874250523}
>>> solar_irradiation(Z=1100.0, latitude=51.0486, longitude=-114.07,
... moment=pytz.timezone('America/Edmonton').localize(datetime(2018, 4, 15, 13, 43, 5)), surface_tilt=41.0,
... linke_turbidity=3, T=300, P=1E5,
... surface_azimuth=180.0, cache=cache)
(1042.567770367, 918.237754854, 124.3300155131, 99.622865737, 24.7071497753)
At night, there is no solar radiation and this function returns zeros:
>>> solar_irradiation(Z=1100.0, latitude=51.0486, longitude=-114.07, linke_turbidity=3,
... moment=pytz.timezone('America/Edmonton').localize(datetime(2018, 4, 15, 2, 43, 5)), surface_tilt=41.0,
... surface_azimuth=180.0)
(0.0, -0.0, 0.0, 0.0, 0.0)
Notes
-----
The retrieval of `linke_turbidity` requires the pytables library (and
Pandas); if it is not installed, specify a value of `linke_turbidity` to
avoid the dependency.
There is some redundancy of the calculated results, according to the
following relations. The total irradiance is normally that desired for
engineering calculations.
poa_diffuse = poa_ground_diffuse + poa_sky_diffuse
poa_global = poa_direct + poa_diffuse
For a surface such as a pipe or vessel, an approach would be to split it
into a number of rectangles and sum up the radiation absorbed by each.
This calculation is fairly slow.
References
----------
.. [1] Will Holmgren, Calama-Consulting, Tony Lorenzo, Uwe Krien, bmu,
DaCoEx, mayudong, et al. Pvlib/Pvlib-Python: 0.5.1. Zenodo, 2017.
https://doi.org/10.5281/zenodo.1016425.
'''
# Atmospheric refraction at sunrise/sunset (0.5667 deg is an often used value)
import calendar
from fluids.optional import spa
from fluids.optional.irradiance import (get_relative_airmass, get_absolute_airmass,
ineichen, get_relative_airmass,
get_absolute_airmass, get_total_irradiance)
moment_timetuple = moment.timetuple()
moment_arg_dni = (moment_timetuple.tm_yday if
extraradiation_method == 'spencer' else moment)
dni_extra = _get_extra_radiation_shim(moment_arg_dni, solar_constant=solar_constant,
method=extraradiation_method,
epoch_year=moment.year)
if T is None or P is None:
atmosphere = ATMOSPHERE_NRLMSISE00(Z=Z, latitude=latitude,
longitude=longitude,
day=moment_timetuple.tm_yday)
if T is None:
T = atmosphere.T
if P is None:
P = atmosphere.P
if cache is not None and 'zenith' in cache:
zenith = cache['zenith']
apparent_zenith = cache['apparent_zenith']
azimuth = cache['azimuth']
else:
apparent_zenith, zenith, _, _, azimuth, _ = solar_position(moment=moment,
latitude=latitude,
longitude=longitude,
Z=Z, T=T, P=P,
atmos_refract=atmos_refract)
if linke_turbidity is None:
try:
import pvlib
except:
raise ImportError(PVLIB_MISSING_MSG)
from pvlib.clearsky import lookup_linke_turbidity
import pandas as pd
linke_turbidity = float(lookup_linke_turbidity(
pd.DatetimeIndex([moment]), latitude, longitude).values)
if airmass_model in apparent_zenith_airmass_models:
used_zenith = apparent_zenith
elif airmass_model in true_zenith_airmass_models:
used_zenith = zenith
else:
raise ValueError('Unrecognized airmass model')
relative_airmass = get_relative_airmass(used_zenith, model=airmass_model)
airmass_absolute = get_absolute_airmass(relative_airmass, pressure=P)
ans = ineichen(apparent_zenith=apparent_zenith,
airmass_absolute=airmass_absolute,
linke_turbidity=linke_turbidity,
altitude=Z, dni_extra=solar_constant, perez_enhancement=True)
ghi = ans['ghi']
dni = ans['dni']
dhi = ans['dhi']
# from pvlib.irradiance import get_total_irradiance
ans = get_total_irradiance(surface_tilt=surface_tilt,
surface_azimuth=surface_azimuth,
solar_zenith=apparent_zenith, solar_azimuth=azimuth,
dni=dni, ghi=ghi, dhi=dhi, dni_extra=dni_extra,
airmass=airmass_absolute, albedo=albedo)
poa_global = float(ans['poa_global'])
poa_direct = float(ans['poa_direct'])
poa_diffuse = float(ans['poa_diffuse'])
poa_sky_diffuse = float(ans['poa_sky_diffuse'])
poa_ground_diffuse = float(ans['poa_ground_diffuse'])
return (poa_global, poa_direct, poa_diffuse, poa_sky_diffuse,
poa_ground_diffuse)
def solar_irradiation(latitude, longitude, Z, moment, surface_tilt,
surface_azimuth, T=None, P=None, solar_constant=1366.1,
atmos_refract=0.5667, albedo=0.25, linke_turbidity=None,
extraradiation_method='spencer',
airmass_model='kastenyoung1989',
cache=None):
r'''Calculates the amount of solar radiation and radiation reflected back
the atmosphere which hits a surface at a specified tilt, and facing a
specified azimuth.
This functions is a wrapper for the incredibly
comprehensive `pvlib library <https://github.com/pvlib/pvlib-python>`_,
and requires it to be installed.
Parameters
----------
latitude : float
Latitude, between -90 and 90 [degrees]
longitude : float
Longitude, between -180 and 180, [degrees]
Z : float, optional
Elevation above sea level for the position, [m]
moment : datetime
Time and date for the calculation, in local UTC time (not daylight
savings time), [-]
surface_tilt : float
The angle above the horizontal of the object being hit by radiation,
[degrees]
surface_azimuth : float
The angle the object is facing (positive North eastwards 0° to 360°),
[degrees]
T : float, optional
Temperature of atmosphere at ground level, [K]
P : float, optional
Pressure of atmosphere at ground level, [Pa]
solar_constant : float, optional
The amount of solar radiation which reaches earth's disk (at a
standardized distance of 1 AU); this constant is independent of
activity or conditions on earth, but will vary throughout the sun's
lifetime and may increase or decrease slightly due to solar activity,
[W/m^2]
atmos_refract : float, optional
Atmospheric refractivity at sunrise/sunset (0.5667 deg is an often used
value; this varies substantially and has an impact of a few minutes on
when sunrise and sunset is), [degrees]
albedo : float, optional
The average amount of reflection of the terrain surrounding the object
at quite a distance; this impacts how much sunlight reflected off the
ground, gest reflected back off clouds, [-]
linke_turbidity : float, optional
The amount of pollution/water in the sky versus a perfect clear sky;
If not specified, this will be retrieved from a historical grid;
typical values are 3 for cloudy, and 7 for severe pollution around a
city, [-]
extraradiation_method : str, optional
The specified method to calculate the effect of earth's position on the
amount of radiation which reaches earth according to the methods
available in the `pvlib` library, [-]
airmass_model : str, optional
The specified method to calculate the amount of air the sunlight
needs to travel through to reach the earth according to the methods
available in the `pvlib` library, [-]
cache : dict, optional
Dictionary to to check for values to use to skip some calculations;
`apparent_zenith`, `zenith`, `azimuth` supported, [-]
Returns
-------
poa_global : float
The total irradiance in the plane of the surface, [W/m^2]
poa_direct : float
The total beam irradiance in the plane of the surface, [W/m^2]
poa_diffuse : float
The total diffuse irradiance in the plane of the surface, [W/m^2]
poa_sky_diffuse : float
The sky component of the diffuse irradiance, excluding the impact
from the ground, [W/m^2]
poa_ground_diffuse : float
The ground-sky diffuse irradiance component, [W/m^2]
Examples
--------
>>> solar_irradiation(Z=1100.0, latitude=51.0486, longitude=-114.07,
... moment=datetime(2018, 4, 15, 13, 43, 5), surface_tilt=41.0,
... surface_azimuth=180.0)
(1065.7621896280812, 945.2656564506323, 120.49653317744884, 95.31535344213178, 25.181179735317063)
>>> cache = {'apparent_zenith': 41.099082295767545, 'zenith': 41.11285376417578, 'azimuth': 182.5631874250523}
>>> solar_irradiation(Z=1100.0, latitude=51.0486, longitude=-114.07,
... moment=datetime(2018, 4, 15, 13, 43, 5), surface_tilt=41.0,
... linke_turbidity=3, T=300, P=1E5,
... surface_azimuth=180.0, cache=cache)
(1042.5677703677097, 918.2377548545295, 124.33001551318027, 99.6228657378363, 24.70714977534396)
At night, there is no solar radiation and this function returns zeros:
>>> solar_irradiation(Z=1100.0, latitude=51.0486, longitude=-114.07,
... moment=datetime(2018, 4, 15, 2, 43, 5), surface_tilt=41.0,
... surface_azimuth=180.0)
(0.0, -0.0, 0.0, 0.0, 0.0)
Notes
-----
The retrieval of `linke_turbidity` requires the pytables library (and
Pandas); if it is not installed, specify a value of `linke_turbidity` to
avoid the dependency.
There is some redundancy of the calculated results, according to the
following relations. The total irradiance is normally that desired for
engineering calculations.
poa_diffuse = poa_ground_diffuse + poa_sky_diffuse
poa_global = poa_direct + poa_diffuse
FOr a surface such as a pipe or vessel, an approach would be to split it
into a number of rectangles and sum up the radiation absorbed by each.
This calculation is fairly slow.
References
----------
.. [1] Will Holmgren, Calama-Consulting, Tony Lorenzo, Uwe Krien, bmu,
DaCoEx, mayudong, et al. Pvlib/Pvlib-Python: 0.5.1. Zenodo, 2017.
https://doi.org/10.5281/zenodo.1016425.
'''
# Atmospheric refraction at sunrise/sunset (0.5667 deg is an often used value)
from fluids.optional import spa
from fluids.optional.irradiance import (get_relative_airmass, get_absolute_airmass,
ineichen, get_relative_airmass,
get_absolute_airmass, get_total_irradiance)
# try:
# import pvlib
# except:
# raise ImportError(PVLIB_MISSING_MSG)
moment_timetuple = moment.timetuple()
moment_arg_dni = (moment_timetuple.tm_yday if
extraradiation_method == 'spencer' else moment)
dni_extra = _get_extra_radiation_shim(moment_arg_dni, solar_constant=solar_constant,
method=extraradiation_method,
epoch_year=moment.year)
if T is None or P is None:
atmosphere = ATMOSPHERE_NRLMSISE00(Z=Z, latitude=latitude,
longitude=longitude,
day=moment_timetuple.tm_yday)
if T is None:
T = atmosphere.T
if P is None:
P = atmosphere.P
if cache is not None and 'zenith' in cache:
zenith = cache['zenith']
apparent_zenith = cache['apparent_zenith']
azimuth = cache['azimuth']
else:
apparent_zenith, zenith, _, _, azimuth, _ = solar_position(moment=moment,
latitude=latitude,
longitude=longitude,
Z=Z, T=T, P=P,
atmos_refract=atmos_refract)
if linke_turbidity is None:
from pvlib.clearsky import lookup_linke_turbidity
import pandas as pd
linke_turbidity = float(lookup_linke_turbidity(
pd.DatetimeIndex([moment]), latitude, longitude).values)
if airmass_model in apparent_zenith_airmass_models:
used_zenith = apparent_zenith
elif airmass_model in true_zenith_airmass_models:
used_zenith = zenith
else:
raise Exception('Unrecognized airmass model')
relative_airmass = get_relative_airmass(used_zenith, model=airmass_model)
airmass_absolute = get_absolute_airmass(relative_airmass, pressure=P)
ans = ineichen(apparent_zenith=apparent_zenith,
airmass_absolute=airmass_absolute,
linke_turbidity=linke_turbidity,
altitude=Z, dni_extra=solar_constant, perez_enhancement=True)
ghi = ans['ghi']
dni = ans['dni']
dhi = ans['dhi']
# from pvlib.irradiance import get_total_irradiance
ans = get_total_irradiance(surface_tilt=surface_tilt,
surface_azimuth=surface_azimuth,
solar_zenith=apparent_zenith, solar_azimuth=azimuth,
dni=dni, ghi=ghi, dhi=dhi, dni_extra=dni_extra,
airmass=airmass_absolute, albedo=albedo)
poa_global = float(ans['poa_global'])
poa_direct = float(ans['poa_direct'])
poa_diffuse = float(ans['poa_diffuse'])
poa_sky_diffuse = float(ans['poa_sky_diffuse'])
poa_ground_diffuse = float(ans['poa_ground_diffuse'])
return (poa_global, poa_direct, poa_diffuse, poa_sky_diffuse,
poa_ground_diffuse)