def test_perez():
AM = atmosphere.relativeairmass(ephem_data['apparent_zenith'])
irradiance.perez(40, 180, irrad_data['DHI'], irrad_data['DNI'],
dni_et,
ephem_data['apparent_zenith'],
ephem_data['apparent_azimuth'],
AM)
def test_perez_components(irrad_data, ephem_data, dni_et, relative_airmass):
dni = irrad_data['dni'].copy()
dni.iloc[2] = np.nan
out = irradiance.perez(40,
180,
irrad_data['dhi'],
dni,
dni_et,
ephem_data['apparent_zenith'],
ephem_data['azimuth'],
relative_airmass,
return_components=True)
expected = pd.DataFrame(
np.array([[0., 31.46046871, np.nan, 45.45539877],
[0., 26.84138589, np.nan, 31.72696071],
[0., 0., np.nan, 4.47966439],
[0., 4.62212181, np.nan, 9.25316454]]).T,
columns=['sky_diffuse', 'isotropic', 'circumsolar', 'horizon'],
index=irrad_data.index)
expected_for_sum = expected['sky_diffuse'].copy()
expected_for_sum.iloc[2] = 0
sum_components = out.iloc[:, 1:].sum(axis=1)
sum_components.name = 'sky_diffuse'
assert_frame_equal(out, expected, check_less_precise=2)
assert_series_equal(sum_components, expected_for_sum, check_less_precise=2)
def test_perez_components():
am = atmosphere.relativeairmass(ephem_data['apparent_zenith'])
dni = irrad_data['dni'].copy()
dni.iloc[2] = np.nan
out, df_components = irradiance.perez(40,
180,
irrad_data['dhi'],
dni,
dni_et,
ephem_data['apparent_zenith'],
ephem_data['azimuth'],
am,
return_components=True)
expected = pd.Series(np.array([0., 31.46046871, np.nan, 45.45539877]),
index=times)
expected_components = pd.DataFrame(
np.array([[0., 26.84138589, np.nan, 31.72696071],
[0., 0., np.nan, 4.47966439],
[0., 4.62212181, np.nan, 9.25316454]]).T,
columns=['isotropic', 'circumsolar', 'horizon'],
index=times)
sum_components = df_components.sum(axis=1)
assert_series_equal(out, expected, check_less_precise=2)
assert_frame_equal(df_components, expected_components)
assert_series_equal(sum_components, expected, check_less_precise=2)
def test_perez_components():
am = atmosphere.relativeairmass(ephem_data['apparent_zenith'])
dni = irrad_data['dni'].copy()
dni.iloc[2] = np.nan
out, df_components = irradiance.perez(40, 180, irrad_data['dhi'], dni,
dni_et, ephem_data['apparent_zenith'],
ephem_data['azimuth'], am, return_components=True)
expected = pd.Series(np.array(
[ 0. , 31.46046871, np.nan, 45.45539877]),
index=times)
expected_components = pd.DataFrame(
np.array([[ 0. , 26.84138589, np.nan, 31.72696071],
[ 0. , 0. , np.nan, 4.47966439],
[ 0. , 4.62212181, np.nan, 9.25316454]]).T,
columns=['isotropic', 'circumsolar', 'horizon'],
index=times
)
if pandas_0_22():
expected_for_sum = expected.copy()
expected_for_sum.iloc[2] = 0
else:
expected_for_sum = expected
sum_components = df_components.sum(axis=1)
assert_series_equal(out, expected, check_less_precise=2)
assert_frame_equal(df_components, expected_components)
assert_series_equal(sum_components, expected_for_sum, check_less_precise=2)
def test_perez_components(irrad_data, ephem_data, dni_et, relative_airmass):
dni = irrad_data['dni'].copy()
dni.iloc[2] = np.nan
out = irradiance.perez(40, 180, irrad_data['dhi'], dni,
dni_et, ephem_data['apparent_zenith'],
ephem_data['azimuth'], relative_airmass,
return_components=True)
expected = pd.DataFrame(np.array(
[[ 0. , 31.46046871, np.nan, 45.45539877],
[ 0. , 26.84138589, np.nan, 31.72696071],
[ 0. , 0. , np.nan, 4.47966439],
[ 0. , 4.62212181, np.nan, 9.25316454]]).T,
columns=['sky_diffuse', 'isotropic', 'circumsolar', 'horizon'],
index=irrad_data.index
)
if pandas_0_22():
expected_for_sum = expected['sky_diffuse'].copy()
expected_for_sum.iloc[2] = 0
else:
expected_for_sum = expected['sky_diffuse']
sum_components = out.iloc[:, 1:].sum(axis=1)
sum_components.name = 'sky_diffuse'
assert_frame_equal(out, expected, check_less_precise=2)
assert_series_equal(sum_components, expected_for_sum, check_less_precise=2)
def test_perez_scalar():
# copied values from fixtures
out = irradiance.perez(40, 180, 118.45831879, 939.95469881,
1321.1655834833093, 10.56413562, 144.76567754,
1.01688136)
# this will fail. out is ndarry with ndim == 0. fix in future version.
# assert np.isscalar(out)
assert_allclose(out, 109.084332)
def test_perez_scalar():
# copied values from fixtures
out = irradiance.perez(40, 180, 118.45831879, 939.95469881,
1321.1655834833093, 10.56413562, 144.76567754,
1.01688136)
# this will fail. out is ndarry with ndim == 0. fix in future version.
# assert np.isscalar(out)
assert_allclose(out, 109.084332)
def test_perez_arrays():
am = atmosphere.relativeairmass(ephem_data['apparent_zenith'])
dni = irrad_data['dni'].copy()
dni.iloc[2] = np.nan
out = irradiance.perez(40, 180, irrad_data['dhi'].values, dni.values,
dni_et, ephem_data['apparent_zenith'].values,
ephem_data['azimuth'].values, am.values)
expected = np.array([0., 31.46046871, np.nan, 45.45539877])
assert_allclose(out, expected, atol=1e-2)
def test_perez(irrad_data, ephem_data, dni_et, relative_airmass):
dni = irrad_data['dni'].copy()
dni.iloc[2] = np.nan
out = irradiance.perez(40, 180, irrad_data['dhi'], dni, dni_et,
ephem_data['apparent_zenith'],
ephem_data['azimuth'], relative_airmass)
expected = pd.Series(np.array([0., 31.46046871, np.nan, 45.45539877]),
index=irrad_data.index)
assert_series_equal(out, expected, check_less_precise=2)
def test_perez_arrays():
am = atmosphere.relativeairmass(ephem_data['apparent_zenith'])
dni = irrad_data['dni'].copy()
dni.iloc[2] = np.nan
out = irradiance.perez(40, 180, irrad_data['dhi'].values, dni.values,
dni_et, ephem_data['apparent_zenith'].values,
ephem_data['azimuth'].values, am.values)
expected = np.array(
[ 0. , 31.46046871, np.nan, 45.45539877])
assert_allclose(out, expected, atol=1e-2)
def test_perez(irrad_data, ephem_data, dni_et, relative_airmass):
dni = irrad_data['dni'].copy()
dni.iloc[2] = np.nan
out = irradiance.perez(40, 180, irrad_data['dhi'], dni,
dni_et, ephem_data['apparent_zenith'],
ephem_data['azimuth'], relative_airmass)
expected = pd.Series(np.array(
[ 0. , 31.46046871, np.nan, 45.45539877]),
index=irrad_data.index)
assert_series_equal(out, expected, check_less_precise=2)
def test_perez_arrays(irrad_data, ephem_data, dni_et, relative_airmass):
dni = irrad_data['dni'].copy()
dni.iloc[2] = np.nan
out = irradiance.perez(40, 180, irrad_data['dhi'].values, dni.values,
dni_et, ephem_data['apparent_zenith'].values,
ephem_data['azimuth'].values,
relative_airmass.values)
expected = np.array([0., 31.46046871, np.nan, 45.45539877])
assert_allclose(out, expected, atol=1e-2)
assert isinstance(out, np.ndarray)
def test_perez_arrays(irrad_data, ephem_data, dni_et, relative_airmass):
dni = irrad_data['dni'].copy()
dni.iloc[2] = np.nan
out = irradiance.perez(40, 180, irrad_data['dhi'].values, dni.values,
dni_et, ephem_data['apparent_zenith'].values,
ephem_data['azimuth'].values, relative_airmass.values)
expected = np.array(
[ 0. , 31.46046871, np.nan, 45.45539877])
assert_allclose(out, expected, atol=1e-2)
assert isinstance(out, np.ndarray)
def test_globalinplane():
aoi = irradiance.aoi(40, 180, ephem_data['apparent_zenith'],
ephem_data['azimuth'])
airmass = atmosphere.relativeairmass(ephem_data['apparent_zenith'])
gr_sand = irradiance.grounddiffuse(40, ghi, surface_type='sand')
diff_perez = irradiance.perez(
40, 180, irrad_data['dhi'], irrad_data['dni'], dni_et,
ephem_data['apparent_zenith'], ephem_data['azimuth'], airmass)
irradiance.globalinplane(
aoi=aoi, dni=irrad_data['dni'], poa_sky_diffuse=diff_perez,
poa_ground_diffuse=gr_sand)
def test_globalinplane():
AOI = irradiance.aoi(40, 180, ephem_data['apparent_zenith'],
ephem_data['apparent_azimuth'])
AM = atmosphere.relativeairmass(ephem_data['apparent_zenith'])
gr_sand = irradiance.grounddiffuse(40, ghi, surface_type='sand')
diff_perez = irradiance.perez(
40, 180, irrad_data['DHI'], irrad_data['DNI'], dni_et,
ephem_data['apparent_zenith'], ephem_data['apparent_azimuth'], AM)
irradiance.globalinplane(
AOI=AOI, DNI=irrad_data['DNI'], In_Plane_SkyDiffuse=diff_perez,
GR=gr_sand)
def test_globalinplane():
aoi = irradiance.aoi(40, 180, ephem_data['apparent_zenith'],
ephem_data['apparent_azimuth'])
airmass = atmosphere.relativeairmass(ephem_data['apparent_zenith'])
gr_sand = irradiance.grounddiffuse(40, ghi, surface_type='sand')
diff_perez = irradiance.perez(
40, 180, irrad_data['dhi'], irrad_data['dni'], dni_et,
ephem_data['apparent_zenith'], ephem_data['apparent_azimuth'], airmass)
irradiance.globalinplane(
aoi=aoi, dni=irrad_data['dni'], poa_sky_diffuse=diff_perez,
poa_ground_diffuse=gr_sand)
def test_globalinplane():
AOI = irradiance.aoi(40, 180, ephem_data['apparent_zenith'],
ephem_data['apparent_azimuth'])
AM = atmosphere.relativeairmass(ephem_data['apparent_zenith'])
gr_sand = irradiance.grounddiffuse(40, ghi, surface_type='sand')
diff_perez = irradiance.perez(40, 180, irrad_data['DHI'],
irrad_data['DNI'], dni_et,
ephem_data['apparent_zenith'],
ephem_data['apparent_azimuth'], AM)
irradiance.globalinplane(AOI=AOI,
DNI=irrad_data['DNI'],
In_Plane_SkyDiffuse=diff_perez,
GR=gr_sand)
def test_perez_negative_horizon():
times = pd.date_range(start='20190101 11:30:00',
freq='1H',
periods=5,
tz='US/Central')
# Avoid test dependencies on functionality not being tested by hard-coding
# the inputs. This data corresponds to Goodwin Creek in the afternoon on
# 1/1/2019.
# dni_e is slightly rounded from irradiance.get_extra_radiation
# airmass from atmosphere.get_relative_airmas
inputs = pd.DataFrame(
np.array([[158, 19, 1, 0, 0], [249, 165, 136, 93, 50],
[57.746951, 57.564205, 60.813841, 66.989435, 75.353368],
[171.003315, 187.346924, 202.974357, 216.725599, 228.317233],
[1414, 1414, 1414, 1414, 1414],
[1.869315, 1.859981, 2.044429, 2.544943, 3.900136]]).T,
columns=[
'dni', 'dhi', 'solar_zenith', 'solar_azimuth', 'dni_extra',
'airmass'
],
index=times)
out = irradiance.perez(34,
180,
inputs['dhi'],
inputs['dni'],
inputs['dni_extra'],
inputs['solar_zenith'],
inputs['solar_azimuth'],
inputs['airmass'],
model='allsitescomposite1990',
return_components=True)
# sky_diffuse can be less than isotropic under certain conditions as
# horizon goes negative
expected = pd.DataFrame(
np.array([[281.410185, 152.20879, 123.867898, 82.836412, 43.517015],
[166.785419, 142.24475, 119.173875, 83.525150, 45.725931],
[113.548755, 16.09757, 9.956174, 3.142467, 0],
[1.076010, -6.13353, -5.262151, -3.831230, -2.208923]]).T,
columns=['sky_diffuse', 'isotropic', 'circumsolar', 'horizon'],
index=times)
expected_for_sum = expected['sky_diffuse'].copy()
sum_components = out.iloc[:, 1:].sum(axis=1)
sum_components.name = 'sky_diffuse'
assert_frame_equal(out, expected, check_less_precise=2)
assert_series_equal(sum_components, expected_for_sum, check_less_precise=2)
def test_poa_components(irrad_data, ephem_data, dni_et, relative_airmass):
aoi = irradiance.aoi(40, 180, ephem_data['apparent_zenith'],
ephem_data['azimuth'])
gr_sand = irradiance.get_ground_diffuse(40, irrad_data['ghi'],
surface_type='sand')
diff_perez = irradiance.perez(
40, 180, irrad_data['dhi'], irrad_data['dni'], dni_et,
ephem_data['apparent_zenith'], ephem_data['azimuth'], relative_airmass)
out = irradiance.poa_components(
aoi, irrad_data['dni'], diff_perez, gr_sand)
expected = pd.DataFrame(np.array(
[[ 0. , -0. , 0. , 0. ,
0. ],
[ 35.19456561, 0. , 35.19456561, 31.4635077 ,
3.73105791],
[956.18253696, 798.31939281, 157.86314414, 109.08433162,
48.77881252],
[ 90.99624896, 33.50143401, 57.49481495, 45.45978964,
12.03502531]]),
columns=['poa_global', 'poa_direct', 'poa_diffuse', 'poa_sky_diffuse',
'poa_ground_diffuse'],
index=irrad_data.index)
assert_frame_equal(out, expected)
def test_poa_components(irrad_data, ephem_data, dni_et, relative_airmass):
aoi = irradiance.aoi(40, 180, ephem_data['apparent_zenith'],
ephem_data['azimuth'])
gr_sand = irradiance.get_ground_diffuse(40,
irrad_data['ghi'],
surface_type='sand')
diff_perez = irradiance.perez(40, 180, irrad_data['dhi'],
irrad_data['dni'], dni_et,
ephem_data['apparent_zenith'],
ephem_data['azimuth'], relative_airmass)
out = irradiance.poa_components(aoi, irrad_data['dni'], diff_perez,
gr_sand)
expected = pd.DataFrame(np.array(
[[0., -0., 0., 0., 0.],
[35.19456561, 0., 35.19456561, 31.4635077, 3.73105791],
[956.18253696, 798.31939281, 157.86314414, 109.08433162, 48.77881252],
[90.99624896, 33.50143401, 57.49481495, 45.45978964, 12.03502531]]),
columns=[
'poa_global', 'poa_direct', 'poa_diffuse',
'poa_sky_diffuse', 'poa_ground_diffuse'
],
index=irrad_data.index)
assert_frame_equal(out, expected)
def test_perez():
AM = atmosphere.relativeairmass(ephem_data['apparent_zenith'])
irradiance.perez(40, 180, irrad_data['dhi'], irrad_data['dni'], dni_et,
ephem_data['apparent_zenith'],
ephem_data['apparent_azimuth'], AM)
def test_perez():
am = atmosphere.relativeairmass(ephem_data['apparent_zenith'])
out = irradiance.perez(40, 180, irrad_data['dhi'], irrad_data['dni'],
dni_et, ephem_data['apparent_zenith'],
ephem_data['azimuth'], am)
assert not out.isnull().any()
def test_perez():
am = atmosphere.relativeairmass(ephem_data['apparent_zenith'])
out = irradiance.perez(40, 180, irrad_data['dhi'], irrad_data['dni'],
dni_et, ephem_data['apparent_zenith'],
ephem_data['azimuth'], am)
assert not out.isnull().any()
def perez_diffuse_luminance(timestamps, surface_tilt, surface_azimuth,
solar_zenith, solar_azimuth, dni, dhi):
"""Function used to calculate the luminance and the view factor terms from the
Perez diffuse light transposition model, as implemented in the
``pvlib-python`` library.
This function was custom made to allow the calculation of the circumsolar
component on the back surface as well. Otherwise, the ``pvlib``
implementation would ignore it.
Parameters
----------
timestamps : array-like
simulation timestamps
surface_tilt : array-like
Surface tilt angles in decimal degrees.
surface_tilt must be >=0 and <=180.
The tilt angle is defined as degrees from horizontal
(e.g. surface facing up = 0, surface facing horizon = 90)
surface_azimuth : array-like
The azimuth of the rotated panel,
determined by projecting the vector normal to the panel's surface to
the earth's surface [degrees].
solar_zenith : array-like
solar zenith angles
solar_azimuth : array-like
solar azimuth angles
dni : array-like
values for direct normal irradiance
dhi : array-like
values for diffuse horizontal irradiance
Returns
-------
df_inputs : `pandas.DataFrame`
Dataframe with the following columns:
['solar_zenith', 'solar_azimuth', 'surface_tilt', 'surface_azimuth',
'dhi', 'dni', 'vf_horizon', 'vf_circumsolar', 'vf_isotropic',
'luminance_horizon', 'luminance_circuqmsolar', 'luminance_isotropic',
'poa_isotropic', 'poa_circumsolar', 'poa_horizon', 'poa_total_diffuse']
"""
# Create a dataframe to help filtering on all arrays
df_inputs = pd.DataFrame(
{
'surface_tilt': surface_tilt,
'surface_azimuth': surface_azimuth,
'solar_zenith': solar_zenith,
'solar_azimuth': solar_azimuth,
'dni': dni,
'dhi': dhi
},
index=pd.DatetimeIndex(timestamps))
dni_et = irradiance.get_extra_radiation(df_inputs.index.dayofyear)
am = atmosphere.get_relative_airmass(df_inputs.solar_zenith)
# Need to treat the case when the sun is hitting the back surface of pvrow
aoi_proj = irradiance.aoi_projection(df_inputs.surface_tilt,
df_inputs.surface_azimuth,
df_inputs.solar_zenith,
df_inputs.solar_azimuth)
sun_hitting_back_surface = ((aoi_proj < 0) &
(df_inputs.solar_zenith <= 90))
df_inputs_back_surface = df_inputs.loc[sun_hitting_back_surface].copy()
# Reverse the surface normal to switch to back-surface circumsolar calc
df_inputs_back_surface.loc[:, 'surface_azimuth'] = (
df_inputs_back_surface.loc[:, 'surface_azimuth'] - 180.)
df_inputs_back_surface.loc[:, 'surface_azimuth'] = np.mod(
df_inputs_back_surface.loc[:, 'surface_azimuth'], 360.)
df_inputs_back_surface.loc[:, 'surface_tilt'] = (
180. - df_inputs_back_surface.surface_tilt)
if df_inputs_back_surface.shape[0] > 0:
# Use recursion to calculate circumsolar luminance for back surface
df_inputs_back_surface = perez_diffuse_luminance(
*breakup_df_inputs(df_inputs_back_surface))
# Calculate Perez diffuse components
components = irradiance.perez(df_inputs.surface_tilt,
df_inputs.surface_azimuth,
df_inputs.dhi,
df_inputs.dni,
dni_et,
df_inputs.solar_zenith,
df_inputs.solar_azimuth,
am,
return_components=True)
# Calculate Perez view factors:
a = irradiance.aoi_projection(df_inputs.surface_tilt,
df_inputs.surface_azimuth,
df_inputs.solar_zenith,
df_inputs.solar_azimuth)
a = np.maximum(a, 0)
b = cosd(df_inputs.solar_zenith)
b = np.maximum(b, cosd(85))
vf_perez = pd.DataFrame(
{
'vf_horizon': sind(df_inputs.surface_tilt),
'vf_circumsolar': a / b,
'vf_isotropic': (1. + cosd(df_inputs.surface_tilt)) / 2.
},
index=df_inputs.index)
# Calculate diffuse luminance
luminance = pd.DataFrame(np.array([
components['horizon'] / vf_perez['vf_horizon'],
components['circumsolar'] / vf_perez['vf_circumsolar'],
components['isotropic'] / vf_perez['vf_isotropic']
]).T,
index=df_inputs.index,
columns=[
'luminance_horizon', 'luminance_circumsolar',
'luminance_isotropic'
])
luminance.loc[components['sky_diffuse'] == 0, :] = 0.
# Format components column names
components = components.rename(
columns={
'isotropic': 'poa_isotropic',
'circumsolar': 'poa_circumsolar',
'horizon': 'poa_horizon'
})
df_inputs = pd.concat([df_inputs, components, vf_perez, luminance],
axis=1,
join='outer')
df_inputs = df_inputs.rename(columns={'sky_diffuse': 'poa_total_diffuse'})
# Adjust the circumsolar luminance when it hits the back surface
if df_inputs_back_surface.shape[0] > 0:
df_inputs.loc[sun_hitting_back_surface, 'luminance_circumsolar'] = (
df_inputs_back_surface.loc[:, 'luminance_circumsolar'])
return df_inputs
def perez_diffuse_luminance(timestamps, array_tilt, array_azimuth,
solar_zenith, solar_azimuth, dni, dhi):
"""
Function used to calculate the luminance and the view factor terms from the
Perez diffuse light transposition model, as implemented in the
``pvlib-python`` library.
This function was custom made to allow the calculation of the circumsolar
component on the back surface as well. Otherwise, the ``pvlib``
implementation would ignore it.
:param array-like timestamps: simulation timestamps
:param array-like array_tilt: pv module tilt angles
:param array-like array_azimuth: pv array azimuth angles
:param array-like solar_zenith: solar zenith angles
:param array-like solar_azimuth: solar azimuth angles
:param array-like dni: values for direct normal irradiance
:param array-like dhi: values for diffuse horizontal irradiance
:return: ``df_inputs``, dataframe with the following columns:
['solar_zenith', 'solar_azimuth', 'array_tilt', 'array_azimuth', 'dhi',
'dni', 'vf_horizon', 'vf_circumsolar', 'vf_isotropic',
'luminance_horizon', 'luminance_circumsolar', 'luminance_isotropic',
'poa_isotropic', 'poa_circumsolar', 'poa_horizon', 'poa_total_diffuse']
:rtype: class:`pandas.DataFrame`
"""
# Create a dataframe to help filtering on all arrays
df_inputs = pd.DataFrame(
{
'array_tilt': array_tilt,
'array_azimuth': array_azimuth,
'solar_zenith': solar_zenith,
'solar_azimuth': solar_azimuth,
'dni': dni,
'dhi': dhi
},
index=pd.DatetimeIndex(timestamps))
dni_et = irradiance.extraradiation(df_inputs.index.dayofyear)
am = atmosphere.relativeairmass(df_inputs.solar_zenith)
# Need to treat the case when the sun is hitting the back surface of pvrow
aoi_proj = aoi_projection(df_inputs.array_tilt, df_inputs.array_azimuth,
df_inputs.solar_zenith, df_inputs.solar_azimuth)
sun_hitting_back_surface = ((aoi_proj < 0) &
(df_inputs.solar_zenith <= 90))
df_inputs_back_surface = df_inputs.loc[sun_hitting_back_surface]
# Reverse the surface normal to switch to back-surface circumsolar calc
df_inputs_back_surface.loc[:, 'array_azimuth'] -= 180.
df_inputs_back_surface.loc[:, 'array_azimuth'] = np.mod(
df_inputs_back_surface.loc[:, 'array_azimuth'], 360.)
df_inputs_back_surface.loc[:, 'array_tilt'] = (
180. - df_inputs_back_surface.array_tilt)
if df_inputs_back_surface.shape[0] > 0:
# Use recursion to calculate circumsolar luminance for back surface
df_inputs_back_surface = perez_diffuse_luminance(
*breakup_df_inputs(df_inputs_back_surface))
# Calculate Perez diffuse components
diffuse_poa, components = irradiance.perez(df_inputs.array_tilt,
df_inputs.array_azimuth,
df_inputs.dhi,
df_inputs.dni,
dni_et,
df_inputs.solar_zenith,
df_inputs.solar_azimuth,
am,
return_components=True)
# Calculate Perez view factors:
a = aoi_projection(df_inputs.array_tilt, df_inputs.array_azimuth,
df_inputs.solar_zenith, df_inputs.solar_azimuth)
a = np.maximum(a, 0)
b = cosd(df_inputs.solar_zenith)
b = np.maximum(b, cosd(85))
vf_perez = pd.DataFrame(
np.array([
sind(df_inputs.array_tilt), a / b,
(1. + cosd(df_inputs.array_tilt)) / 2.
]).T,
index=df_inputs.index,
columns=['vf_horizon', 'vf_circumsolar', 'vf_isotropic'])
# Calculate diffuse luminance
luminance = pd.DataFrame(np.array([
components['horizon'] / vf_perez['vf_horizon'],
components['circumsolar'] / vf_perez['vf_circumsolar'],
components['isotropic'] / vf_perez['vf_isotropic']
]).T,
index=df_inputs.index,
columns=[
'luminance_horizon', 'luminance_circumsolar',
'luminance_isotropic'
])
luminance.loc[diffuse_poa == 0, :] = 0.
# Format components column names
components = components.rename(
columns={
'isotropic': 'poa_isotropic',
'circumsolar': 'poa_circumsolar',
'horizon': 'poa_horizon'
})
df_inputs = pd.concat(
[df_inputs, components, vf_perez, luminance, diffuse_poa],
axis=1,
join='outer')
df_inputs = df_inputs.rename(columns={0: 'poa_total_diffuse'})
# Adjust the circumsolar luminance when it hits the back surface
if df_inputs_back_surface.shape[0] > 0:
df_inputs.loc[sun_hitting_back_surface, 'luminance_circumsolar'] = (
df_inputs_back_surface.loc[:, 'luminance_circumsolar'])
return df_inputs
def test_perez_scalar():
# copied values from fixtures
out = irradiance.perez(40, 180, 118.45831879, 939.95469881,
1321.1655834833093, 10.56413562, 144.76567754,
1.01688136)
assert_allclose(out, 109.084332)
def perez_diffuse_luminance(df_inputs):
"""
Function used to calculate the luminance and the view factor terms from the
Perez diffuse light transposition model, as implemented in the
``pvlib-python`` library.
:param df_inputs: class:`pandas.DataFrame` with following columns:
['solar_zenith', 'solar_azimuth', 'array_tilt', 'array_azimuth', 'dhi',
'dni']. Units are: ['deg', 'deg', 'deg', 'deg', 'W/m2', 'W/m2']
:return: class:`pandas.DataFrame` with the following columns:
['solar_zenith', 'solar_azimuth', 'array_tilt', 'array_azimuth', 'dhi',
'dni', 'vf_horizon', 'vf_circumsolar', 'vf_isotropic',
'luminance_horizon', 'luminance_circumsolar', 'luminance_isotropic',
'poa_isotropic', 'poa_circumsolar', 'poa_horizon', 'poa_total_diffuse']
"""
dni_et = irradiance.extraradiation(df_inputs.index.dayofyear)
am = atmosphere.relativeairmass(df_inputs.solar_zenith)
# Need to treat the case when the sun is hitting the back surface of pvrow
aoi_proj = aoi_projection(df_inputs.array_tilt, df_inputs.array_azimuth,
df_inputs.solar_zenith, df_inputs.solar_azimuth)
sun_hitting_back_surface = ((aoi_proj < 0) &
(df_inputs.solar_zenith <= 90))
df_inputs_back_surface = df_inputs.loc[sun_hitting_back_surface]
# Reverse the surface normal to switch to back-surface circumsolar calc
df_inputs_back_surface.loc[:, 'array_azimuth'] -= 180.
df_inputs_back_surface.loc[:, 'array_azimuth'] = np.mod(
df_inputs_back_surface.loc[:, 'array_azimuth'], 360.
)
df_inputs_back_surface.loc[:, 'array_tilt'] = (
180. - df_inputs_back_surface.array_tilt)
if df_inputs_back_surface.shape[0] > 0:
# Use recursion to calculate circumsolar luminance for back surface
df_inputs_back_surface = perez_diffuse_luminance(
df_inputs_back_surface)
# Calculate Perez diffuse components
diffuse_poa, components = irradiance.perez(df_inputs.array_tilt,
df_inputs.array_azimuth,
df_inputs.dhi, df_inputs.dni,
dni_et,
df_inputs.solar_zenith,
df_inputs.solar_azimuth,
am,
return_components=True)
# Calculate Perez view factors:
a = aoi_projection(df_inputs.array_tilt, df_inputs.array_azimuth,
df_inputs.solar_zenith, df_inputs.solar_azimuth)
a = np.maximum(a, 0)
b = cosd(df_inputs.solar_zenith)
b = np.maximum(b, cosd(85))
vf_perez = pd.DataFrame(
np.array([
sind(df_inputs.array_tilt),
a / b,
(1. + cosd(df_inputs.array_tilt)) / 2.
]).T,
index=df_inputs.index,
columns=['vf_horizon', 'vf_circumsolar', 'vf_isotropic']
)
# Calculate diffuse luminance
luminance = pd.DataFrame(
np.array([
components['horizon'] / vf_perez['vf_horizon'],
components['circumsolar'] / vf_perez['vf_circumsolar'],
components['isotropic'] / vf_perez['vf_isotropic']
]).T,
index=df_inputs.index,
columns=['luminance_horizon', 'luminance_circumsolar',
'luminance_isotropic']
)
luminance.loc[diffuse_poa == 0, :] = 0.
# Format components column names
components = components.rename(columns={'isotropic': 'poa_isotropic',
'circumsolar': 'poa_circumsolar',
'horizon': 'poa_horizon'})
df_inputs = pd.concat([df_inputs, components, vf_perez, luminance,
diffuse_poa],
axis=1, join='outer')
df_inputs = df_inputs.rename(columns={0: 'poa_total_diffuse'})
# Adjust the circumsolar luminance when it hits the back surface
if df_inputs_back_surface.shape[0] > 0:
df_inputs.loc[sun_hitting_back_surface, 'luminance_circumsolar'] = (
df_inputs_back_surface.loc[:, 'luminance_circumsolar']
)
return df_inputs
