def test_physical_scalar():
aoi = -45.
iam = _iam.physical(aoi, 1.526, 0.002, 4)
expected = 0.98797788
assert_allclose(iam, expected, equal_nan=True)
aoi = np.nan
iam = _iam.physical(aoi, 1.526, 0.002, 4)
expected = np.nan
assert_allclose(iam, expected, equal_nan=True)
def test_physical():
aoi = np.array(
[-90., -67.5, -45., -22.5, 0., 22.5, 45., 67.5, 90., np.nan])
expected = np.array([
0, 0.8893998, 0.98797788, 0.99926198, 1, 0.99926198, 0.98797788,
0.8893998, 0, np.nan
])
iam = _iam.physical(aoi, 1.526, 0.002, 4)
assert_allclose(iam, expected, equal_nan=True)
# GitHub issue 397
aoi = pd.Series(aoi)
iam = _iam.physical(aoi, 1.526, 0.002, 4)
expected = pd.Series(expected)
assert_series_equal(iam, expected)
# The IAM model used to generate the figures in [1]_ uses Snell's, Fresnel's,
# and Beer's laws to determine the fraction of light transmitted through the
# air-glass interface as a function of AOI.
# The function :py:func:`pvlib.iam.physical` implements this model, except it
# also includes an exponential term to model attenuation in the glazing layer.
# To be faithful to Marion's implementation, we will disable this extinction
# term by setting the attenuation coefficient ``K`` parameter to zero.
# For more details on this IAM model, see [2]_.
#
# Marion generated diffuse irradiance modifiers for two cases: a standard
# uncoated glass with index of refraction n=1.526 and a glass with
# anti-reflective (AR) coating with n=1.3.
# Comparing the IAM model across AOI recreates Figure 3 in [1]_:
aoi = np.arange(0, 91)
iam_no_coating = physical(aoi, n=1.526, K=0)
iam_ar_coating = physical(aoi, n=1.3, K=0)
plt.plot(aoi, iam_ar_coating, c='b', label='$F_b$, AR coated, n=1.3')
plt.plot(aoi, iam_no_coating, c='r', label='$F_b$, uncoated, n=1.526')
plt.xlabel(r'Angle-of-Incidence, AOI $(\degree)$')
plt.ylabel('Diffuse Incidence Angle Modifier')
plt.legend()
plt.ylim([0, 1.2])
plt.grid()
# %%
# Diffuse sky, ground, and horizon IAM
# ------------------------------------
#
# Now that we have an AOI model, we use :py:func:`pvlib.iam.marion_diffuse`