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limit cos(aoi) in diffuse sky functions #535

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Merged
merged 8 commits into from
Aug 19, 2018
Merged

limit cos(aoi) in diffuse sky functions #535

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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
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5 changes: 5 additions & 0 deletions docs/sphinx/source/whatsnew/v0.6.0.rst
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Expand Up @@ -109,6 +109,11 @@ Bug fixes
* Make GitHub recognize the license, add AUTHORS.md, clarify shared copyright.
(:issue:`503`)
* Fix argument order of longitude and latitude when querying weather forecasts by lonlat bounding box (:issue:`521`)
* 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`)


Documentation
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10 changes: 7 additions & 3 deletions pvlib/irradiance.py
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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.minimum(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.minimum(cos_tt, 0) # GH 526
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This should be np.maximum

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Hay and Davies:

test_haydavies fails because of this error np.minimum. Otherwise I believe it should pass.

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.minimum(cos_tt, 0) # GH 526
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np.maximum here


# 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