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Add optional arguments temperature_ref and irradiance_ref to pvsystem.sapm #2434

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Merged
kandersolar merged 16 commits into from
Apr 21, 2025
+26 −23
Merged

Add optional arguments temperature_ref and irradiance_ref to pvsystem.sapm #2434

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a564b32
add ref irr/t as optional args, rename
RDaxini Apr 10, 2025
9dc23d3
add terms to docs
RDaxini Apr 10, 2025
0b0b94c
linter
RDaxini Apr 10, 2025
9288c3e
Update v0.12.1.rst
RDaxini Apr 10, 2025
e8c427a
move whatsnew entry from docs to enhancements
RDaxini Apr 10, 2025
2360f16
multiple instances of C -> °C
RDaxini Apr 11, 2025
fe57151
name change (#825)
RDaxini Apr 11, 2025
e8a7b10
Update v0.12.1.rst
RDaxini Apr 11, 2025
c8f5ce2
Merge remote-tracking branch 'upstream/main' into pvsystem_ref_temp_irr
RDaxini Apr 11, 2025
2a55f21
missing `
RDaxini Apr 14, 2025
787afa0
remove unused package
RDaxini Apr 14, 2025
b5c5455
change to kwarg only parameters
RDaxini Apr 14, 2025
3340e50
Revert "Update v0.12.1.rst"
RDaxini Apr 16, 2025
87ca155
update names, remove duplicate entry
RDaxini Apr 16, 2025
0556b9d
remove ivtools line. mistakenly added during merge branch?
RDaxini Apr 16, 2025
090ea79
Update docs/sphinx/source/whatsnew/v0.12.1.rst
RDaxini Apr 18, 2025
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2 changes: 2 additions & 0 deletions docs/sphinx/source/whatsnew/v0.12.1.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,8 @@ Documentation
* Add a supporting reference to :py:func:`pvlib.atmosphere.get_relative_airmass` (:issue:`2390`, :pull:`2424`)
* Documented how `np.nan` values are handled by :py:func:`~pvlib.spectrum.average_photon_energy`
(:issue:`2423`, :pull:`2426`)
* Add optional arguments `reference_temperature` and `reference_irradiance` to
:py:func:`~pvlib.pvsystem.sapm`(:issue:`2432`, :pull:`2434`)

Testing
~~~~~~~
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31 changes: 17 additions & 14 deletions pvlib/pvsystem.py
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Expand Up @@ -2195,7 +2195,8 @@ def _parse_raw_sam_df(csvdata):
return df


def sapm(effective_irradiance, temp_cell, module):
def sapm(effective_irradiance, temp_cell, module, reference_temperature=25,
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@echedey-ls echedey-ls Apr 11, 2025

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Suggested change
def sapm(effective_irradiance, temp_cell, module, reference_temperature=25,
def sapm(effective_irradiance, temp_cell, module, *, reference_temperature=25,

Consider using kwarg-only parameters to enforce readability of code. For future issues debugging, ...
Completely optional suggestion, it's not a common trend in pvlib.

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@RDaxini RDaxini Apr 11, 2025

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I'm not familiar with what this is doing actually... could you elaborate or forward a link for me to review?
You noted it's optional / uncommon in pvlib currently, so I'll just let others comment whether to go ahead with this as I have no idea 😅

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@echedey-ls echedey-ls Apr 11, 2025

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Quick lookup on the internet and you will have a ton of information more extensive, but here is a short example, where all statements are expected to print Hola Dax. The star means the following arguments are only allowed to be passed in as keyword-only (parameter_name=value):

def hola_dax(greet, name):
    print(f"{greet} {name}")

# allowed uses
hola_dax("Hola", "Dax")
hola_dax("Hola", name="Dax")
hola_dax(greet="Hola", name="Dax")
hola_dax(name="Dax", greet="Hola")

# however
def hola_dax(greet, *, name):
    print(f"{greet} {name}")
# only allows using the forms:
hola_dax("Hola", name="Dax")
hola_dax(greet="Hola", name="Dax")
# this raises an error:
hola_dax("Hola", "Dax")  # TypeError: hola_dax() takes 1 positional argument but 2 were given

# and the form
def hola_dax(*, greet, name):
    print(f"{greet} {name}")
# only allows:
hola_dax(greet="Hola", name="Dax")
hola_dax(name="Dax", greet="Hola")

This way, you can always enforce people to make readable code.

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@RDaxini RDaxini Apr 14, 2025

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Right ok got it! Seems like a good suggestion to me. Thanks @echedey-ls

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@RDaxini RDaxini Apr 14, 2025

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https://pvlib-python--2434.org.readthedocs.build/en/2434/reference/generated/pvlib.pvsystem.sapm.html#pvlib.pvsystem.sapm
Should * show here in the function, and if so is there any need to document that below in the parameter descriptions...?

reference_irradiance=1000):
'''
The Sandia PV Array Performance Model (SAPM) generates 5 points on a
PV module's I-V curve (Voc, Isc, Ix, Ixx, Vmp/Imp) according to
Expand All @@ -2205,7 +2206,7 @@ def sapm(effective_irradiance, temp_cell, module):
----------
effective_irradiance : numeric
Irradiance reaching the module's cells, after reflections and
adjustment for spectrum. [W/m2]
adjustment for spectrum. [Wm⁻²]

temp_cell : numeric
Cell temperature [C].
Expand All @@ -2214,6 +2215,12 @@ def sapm(effective_irradiance, temp_cell, module):
A dict or Series defining the SAPM parameters. See the notes section
for more details.

reference_temperature : numeric, optional
Reference temperature [C]

reference_irradiance : numeric, optional
Reference irradiance [Wm⁻²]

Returns
-------
A DataFrame with the columns:
Expand Down Expand Up @@ -2284,16 +2291,11 @@ def sapm(effective_irradiance, temp_cell, module):
pvlib.temperature.sapm_module
'''

# TODO: someday, change temp_ref and irrad_ref to reference_temperature and
# reference_irradiance and expose
temp_ref = 25
irrad_ref = 1000

q = constants.e # Elementary charge in units of coulombs
kb = constants.k # Boltzmann's constant in units of J/K

# avoid problem with integer input
Ee = np.array(effective_irradiance, dtype='float64') / irrad_ref
Ee = np.array(effective_irradiance, dtype='float64') / reference_irradiance

# set up masking for 0, positive, and nan inputs
Ee_gt_0 = np.full_like(Ee, False, dtype='bool')
Expand All @@ -2316,31 +2318,32 @@ def sapm(effective_irradiance, temp_cell, module):
out = OrderedDict()

out['i_sc'] = (
module['Isco'] * Ee * (1 + module['Aisc']*(temp_cell - temp_ref)))
module['Isco'] * Ee * (1 + module['Aisc']*(temp_cell -
reference_temperature)))

out['i_mp'] = (
module['Impo'] * (module['C0']*Ee + module['C1']*(Ee**2)) *
(1 + module['Aimp']*(temp_cell - temp_ref)))
(1 + module['Aimp']*(temp_cell - reference_temperature)))

out['v_oc'] = np.maximum(0, (
module['Voco'] + cells_in_series * delta * logEe +
Bvoco*(temp_cell - temp_ref)))
Bvoco*(temp_cell - reference_temperature)))

out['v_mp'] = np.maximum(0, (
module['Vmpo'] +
module['C2'] * cells_in_series * delta * logEe +
module['C3'] * cells_in_series * ((delta * logEe) ** 2) +
Bvmpo*(temp_cell - temp_ref)))
Bvmpo*(temp_cell - reference_temperature)))

out['p_mp'] = out['i_mp'] * out['v_mp']

out['i_x'] = (
module['IXO'] * (module['C4']*Ee + module['C5']*(Ee**2)) *
(1 + module['Aisc']*(temp_cell - temp_ref)))
(1 + module['Aisc']*(temp_cell - reference_temperature)))

out['i_xx'] = (
module['IXXO'] * (module['C6']*Ee + module['C7']*(Ee**2)) *
(1 + module['Aimp']*(temp_cell - temp_ref)))
(1 + module['Aimp']*(temp_cell - reference_temperature)))

if isinstance(out['i_sc'], pd.Series):
out = pd.DataFrame(out)
Expand Down