Skip to content

limit cos(aoi) in diffuse sky functions #535

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 8 commits into from
Aug 19, 2018
Merged

limit cos(aoi) in diffuse sky functions #535

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
8 commits
Select commit Hold shift + click to select a range
9a74404
limit cos(aoi) in diffuse sky functions
wholmgren Aug 14, 2018
c8530a2
no limit on cos_solar_zenith in hb calculation. change proj limit to -1
wholmgren Aug 14, 2018
c0943a8
reimplement without projection_minimum kwarg
wholmgren Aug 17, 2018
205cc16
fix np.minimum vs. np.maximum
wholmgren Aug 18, 2018
1122055
update tutorial
wholmgren Aug 18, 2018
0e3fb1a
add sky diffuse test for zenith close to 90
wholmgren Aug 18, 2018
e23d9d3
Merge remote-tracking branch 'pvlib/master' into aoidiff
wholmgren Aug 19, 2018
eead186
fix botched whatsnew merge [skip ci]
wholmgren Aug 19, 2018
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
5 changes: 5 additions & 0 deletions docs/sphinx/source/whatsnew/v0.6.0.rst
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -111,6 +111,11 @@ Bug fixes
floats and NumPy arrays. (:issue:`508`)
* Make GitHub recognize the license, add AUTHORS.md, clarify shared copyright.
(:issue:`503`)
* Fix issue with non-zero direct irradiance contribution to Reindl, Klucher,
and Hay-Davies diffuse sky algorithms when the sun is behind the array.
(:issue:`526`)
* Fix issue with dividing by near-0 cos(solar_zenith) values in Reindl and
Hay-Davies diffuse sky algorithms. (:issue:`432`)
* Fix argument order of longitude and latitude when querying weather forecasts
by lonlat bounding box (:issue:`521`)

Expand Down
78 changes: 39 additions & 39 deletions docs/tutorials/irradiance.ipynb
View file
Open in desktop

Large diffs are not rendered by default.

10 changes: 7 additions & 3 deletions pvlib/irradiance.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -256,7 +256,7 @@ def poa_horizontal_ratio(surface_tilt, surface_azimuth,

cos_solar_zenith = tools.cosd(solar_zenith)

# ratio of titled and horizontal beam irradiance
# ratio of tilted and horizontal beam irradiance
ratio = cos_poa_zen / cos_solar_zenith

try:
Expand Down Expand Up @@ -746,6 +746,7 @@ def klucher(surface_tilt, surface_azimuth, dhi, ghi, solar_zenith,
# zenith angle with respect to panel normal.
cos_tt = aoi_projection(surface_tilt, surface_azimuth,
solar_zenith, solar_azimuth)
cos_tt = np.maximum(cos_tt, 0) # GH 526

F = 1 - ((dhi / ghi) ** 2)
try:
Expand Down Expand Up @@ -836,8 +837,9 @@ def haydavies(surface_tilt, surface_azimuth, dhi, dni, dni_extra,
if projection_ratio is None:
cos_tt = aoi_projection(surface_tilt, surface_azimuth,
solar_zenith, solar_azimuth)
cos_tt = np.maximum(cos_tt, 0) # GH 526
cos_solar_zenith = tools.cosd(solar_zenith)
Rb = cos_tt / cos_solar_zenith
Rb = cos_tt / np.maximum(cos_solar_zenith, 0.01745) # GH 432
else:
Rb = projection_ratio

Expand Down Expand Up @@ -932,11 +934,13 @@ def reindl(surface_tilt, surface_azimuth, dhi, dni, ghi, dni_extra,

cos_tt = aoi_projection(surface_tilt, surface_azimuth,
solar_zenith, solar_azimuth)
cos_tt = np.maximum(cos_tt, 0) # GH 526

# do not apply cos(zen) limit here (needed for HB below)
cos_solar_zenith = tools.cosd(solar_zenith)

# ratio of titled and horizontal beam irradiance
Rb = cos_tt / cos_solar_zenith
Rb = cos_tt / np.maximum(cos_solar_zenith, 0.01745) # GH 432

# Anisotropy Index
AI = dni / dni_extra
Expand Down
20 changes: 17 additions & 3 deletions pvlib/test/test_irradiance.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -181,7 +181,9 @@ def test_klucher_series(irrad_data, ephem_data):
result = irradiance.klucher(40, 180, irrad_data['dhi'], irrad_data['ghi'],
ephem_data['apparent_zenith'],
ephem_data['azimuth'])
assert_allclose(result, [0, 37.446276, 109.209347, 56.965916], atol=1e-4)
# pvlib matlab 1.4 does not contain the max(cos_tt, 0) correction
# so, these values are different
assert_allclose(result, [0., 36.789794, 109.209347, 56.965916], atol=1e-4)
# expect same result for np.array and pd.Series
expected = irradiance.klucher(
40, 180, irrad_data['dhi'].values, irrad_data['ghi'].values,
Expand All @@ -195,15 +197,17 @@ def test_haydavies(irrad_data, ephem_data, dni_et):
dni_et,
ephem_data['apparent_zenith'],
ephem_data['azimuth'])
assert_allclose(result, [0, 14.967008, 102.994862, 33.190865], atol=1e-4)
# values from matlab 1.4 code
assert_allclose(result, [0, 27.1775, 102.9949, 33.1909], atol=1e-4)


def test_reindl(irrad_data, ephem_data, dni_et):
result = irradiance.reindl(40, 180, irrad_data['dhi'], irrad_data['dni'],
irrad_data['ghi'], dni_et,
ephem_data['apparent_zenith'],
ephem_data['azimuth'])
assert_allclose(result, [np.nan, 15.730664, 104.131724, 34.166258], atol=1e-4)
# values from matlab 1.4 code
assert_allclose(result, [np.nan, 27.9412, 104.1317, 34.1663], atol=1e-4)


def test_king(irrad_data, ephem_data):
Expand Down Expand Up @@ -265,6 +269,16 @@ def test_perez_arrays(irrad_data, ephem_data, dni_et, relative_airmass):
assert_allclose(out, expected, atol=1e-2)


@pytest.mark.parametrize('model', ['isotropic', 'klucher', 'haydavies',
'reindl', 'king', 'perez'])
def test_sky_diffuse_zenith_close_to_90(model):
# GH 432
sky_diffuse = irradiance.get_sky_diffuse(
30, 180, 89.999, 230,
dni=10, ghi=51, dhi=50, dni_extra=1360, airmass=12, model=model)
assert sky_diffuse < 100


def test_liujordan():
expected = pd.DataFrame(np.
array([[863.859736967, 653.123094076, 220.65905025]]),
Expand Down