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Fix fuentes error for tz-aware inputs #1072

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Merged
merged 3 commits into from
Oct 9, 2020
Merged

Fix fuentes error for tz-aware inputs #1072

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de88dce
swap out timedelta calculation; add tz test
kandersolar Oct 1, 2020
29f8db1
whatsnew
kandersolar Oct 1, 2020
c1f88e3
suggestion from review
kandersolar Oct 9, 2020
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3 changes: 2 additions & 1 deletion docs/sphinx/source/whatsnew/v0.8.1.rst
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Expand Up @@ -17,7 +17,8 @@ Enhancements

Bug fixes
~~~~~~~~~

* Fix issue with :py:func:`pvlib.temperature.fuentes` with timezone-aware
inputs. (:issue:`1071`, :pull:`1072`)

Testing
~~~~~~~
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3 changes: 2 additions & 1 deletion pvlib/temperature.py
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Expand Up @@ -599,7 +599,8 @@ def fuentes(poa_global, temp_air, wind_speed, noct_installed, module_height=5,
# n.b. the way Fuentes calculates the first timedelta makes it seem like
# the value doesn't matter -- rather than recreate it here, just assume
# it's the same as the second timedelta:
timedelta_hours = np.diff(poa_global.index).astype(float) / 1e9 / 60 / 60
timedeltas = (poa_global.index[1:] - poa_global.index[:-1])
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@wholmgren wholmgren Oct 8, 2020

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is this equivalent to poa_global.index.to_series().diff().total_seconds() / 3600?

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@kandersolar kandersolar Oct 9, 2020

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The type is different (series vs index), but that doesn't matter in this context. With timedelta_hours.iloc[0] = timedelta_hours.iloc[1], the two are equivalent, so I'll use yours 👍

timedelta_hours = timedeltas.total_seconds() / 60 / 60
timedelta_hours = np.append([timedelta_hours[0]], timedelta_hours)

tamb_array = temp_air + 273.15
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14 changes: 14 additions & 0 deletions pvlib/tests/test_temperature.py
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Expand Up @@ -190,3 +190,17 @@ def test_fuentes(filename, inoct):
night_difference = expected_tcell[is_night] - actual_tcell[is_night]
assert night_difference.max() < 6
assert night_difference.min() > 0


@pytest.mark.parametrize('tz', [None, 'Etc/GMT+5'])
def test_fuentes_timezone(tz):
index = pd.date_range('2019-01-01', freq='h', periods=3, tz=tz)

df = pd.DataFrame({'poa_global': 1000, 'temp_air': 20, 'wind_speed': 1},
index)

out = temperature.fuentes(df['poa_global'], df['temp_air'],
df['wind_speed'], noct_installed=45)

assert_series_equal(out, pd.Series([47.85, 50.85, 50.85], index=index,
name='tmod'))