From fdc65f0bb2ccd88bf1199e39312f9b5344ae7a7f Mon Sep 17 00:00:00 2001
From: echedey-ls <80125792+echedey-ls@users.noreply.github.com>
Date: Sun, 24 Mar 2024 13:24:51 +0100
Subject: [PATCH 01/17] Add quantum_efficiency_to_spectral_responsivity and
 spectral_responsivity_to_quantum_efficiency

---
 .../effects_on_pv_system_output/spectrum.rst  |   2 +
 pvlib/spectrum/__init__.py                    |   2 +
 pvlib/spectrum/mismatch.py                    | 137 +++++++++++++++++-
 pvlib/tests/test_spectrum.py                  |  90 +++++++++++-
 4 files changed, 229 insertions(+), 2 deletions(-)

diff --git a/docs/sphinx/source/reference/effects_on_pv_system_output/spectrum.rst b/docs/sphinx/source/reference/effects_on_pv_system_output/spectrum.rst
index 8041d8f49b..9d2e4c51a5 100644
--- a/docs/sphinx/source/reference/effects_on_pv_system_output/spectrum.rst
+++ b/docs/sphinx/source/reference/effects_on_pv_system_output/spectrum.rst
@@ -13,3 +13,5 @@ Spectrum
    spectrum.spectral_factor_caballero
    spectrum.spectral_factor_firstsolar
    spectrum.spectral_factor_sapm
+   spectrum.spectral_responsivity_to_quantum_efficiency
+   spectrum.quantum_efficiency_to_spectral_responsivity
diff --git a/pvlib/spectrum/__init__.py b/pvlib/spectrum/__init__.py
index 6c97df978e..00473e1708 100644
--- a/pvlib/spectrum/__init__.py
+++ b/pvlib/spectrum/__init__.py
@@ -6,4 +6,6 @@
     spectral_factor_caballero,
     spectral_factor_firstsolar,
     spectral_factor_sapm,
+    spectral_responsivity_to_quantum_efficiency,
+    quantum_efficiency_to_spectral_responsivity,
 )
diff --git a/pvlib/spectrum/mismatch.py b/pvlib/spectrum/mismatch.py
index e51cdf8625..500573efdf 100644
--- a/pvlib/spectrum/mismatch.py
+++ b/pvlib/spectrum/mismatch.py
@@ -6,11 +6,20 @@
 import numpy as np
 import pandas as pd
 from scipy.interpolate import interp1d
+import scipy.constants
 import os
 
 from warnings import warn
 
 
+_PLANCK_BY_LIGHT_SPEED_OVER_ELEMENTAL_CHARGE_BY_BILLION = (
+    scipy.constants.speed_of_light
+    * scipy.constants.Planck
+    / scipy.constants.elementary_charge
+    * 1e9
+)
+
+
 def get_example_spectral_response(wavelength=None):
     '''
     Generate a generic smooth spectral response (SR) for tests and experiments.
@@ -153,7 +162,7 @@ def calc_spectral_mismatch_field(sr, e_sun, e_ref=None):
 
     e_sun: pandas.DataFrame or pandas.Series
         One or more measured solar irradiance spectra in a pandas.DataFrame
-        having wavelength in nm as column index.  A single spectrum may be
+        having wavelength in nm as column index. A single spectrum may be
         be given as a pandas.Series having wavelength in nm as index.
         [(W/m^2)/nm]
 
@@ -570,3 +579,129 @@ def spectral_factor_caballero(precipitable_water, airmass_absolute, aod500,
     )
     modifier = f_AM + f_AOD + f_PW  # Eq 5
     return modifier
+
+
+def spectral_responsivity_to_quantum_efficiency(sr, wavelength=None):
+    """
+    Convert spectral responsivities to quantum efficiencies [1]_.
+    If ``wavelength`` is not provided, the spectral responsivity ``sr`` must be
+    a :py:class:`pandas.Series` or :py:class:`pandas.DataFrame`, with the
+    wavelengths in the index.
+
+    Provide wavelengths in nanometers :math:`[nm]`.
+
+    .. versionadded:: 0.10.5
+
+    Parameters
+    ----------
+    sr : numeric, pandas.Series or pandas.DataFrame
+        Spectral response.
+        Index must be the wavelength in nanometers :math:`nm`.
+
+    wavelength : numeric, optional
+        Points where spectral response is measured, in nanometers :math:`nm`.
+
+    Returns
+    -------
+    quantum_efficiency : numeric, same type as ``sr``
+        Quantum efficiency in the interval :math:`[0, 1]`.
+
+    Notes
+    -----
+    - If ``sr`` is of type ``pandas.Series`` or ``pandas.DataFrame``,
+      column names will remain unchanged in the returned object.
+    - If ``wavelength`` is provided it will be used independently of the
+      datatype of ``sr``.
+
+    References
+    ----------
+    .. [1] “Spectral Response,” PV Performance Modeling Collaborative (PVPMC).
+        https://pvpmc.sandia.gov/modeling-guide/2-dc-module-iv/
+        effective-irradiance/spectral-response/
+    .. [2] “Spectral Response | PVEducation,” www.pveducation.org.
+        https://www.pveducation.org/pvcdrom/solar-cell-operation/
+        spectral-response
+
+    See Also
+    --------
+    pvlib.spectrum.quantum_efficiency_to_spectral_responsivity
+    """
+    if wavelength is None:
+        if hasattr(sr, "index"):  # true for pandas objects
+            # use reference to index values instead of index alone so
+            # sr / wavelength returns a series with the same name
+            wavelength = sr.index.array
+        else:
+            raise TypeError(
+                "'sr' must have an '.index' attribute"
+                + " or 'wavelength' must be provided"
+            )
+    quantum_efficiency = (
+        sr
+        / wavelength
+        * _PLANCK_BY_LIGHT_SPEED_OVER_ELEMENTAL_CHARGE_BY_BILLION
+    )
+    return quantum_efficiency
+
+
+def quantum_efficiency_to_spectral_responsivity(qe, wavelength=None):
+    """
+    Convert quantum efficiencies to spectral responsivities [1]_.
+    If ``wavelength`` is not provided, the quantum efficiency ``qe`` must be
+    a :py:class:`pandas.Series` or :py:class:`pandas.DataFrame`, with the
+    wavelengths in the index.
+
+    Provide wavelengths in nanometers :math:`[nm]`.
+
+    .. versionadded:: 0.10.5
+
+    Parameters
+    ----------
+    qe : numeric, pandas.Series or pandas.DataFrame
+        Quantum efficiency.
+        If pandas subtype, index must be the wavelength in nanometers.
+
+    wavelength : numeric, optional
+        Points where quantum efficiency is measured, in nanometers :math:`nm`.
+
+    Returns
+    -------
+    spectral_response : numeric, same type as ``qe``
+        Spectral response in :math:`A/W`.
+
+    Notes
+    -----
+    - If ``qe`` is of type ``pandas.Series`` or ``pandas.DataFrame``,
+      column names will remain unchanged in the returned object.
+    - If ``wavelength`` is provided it will be used independently of the
+      datatype of ``qe``.
+
+    References
+    ----------
+    .. [1] “Spectral Response,” PV Performance Modeling Collaborative (PVPMC).
+        https://pvpmc.sandia.gov/modeling-guide/2-dc-module-iv/
+        effective-irradiance/spectral-response/
+    .. [2] “Spectral Response | PVEducation,” www.pveducation.org.
+        https://www.pveducation.org/pvcdrom/solar-cell-operation/
+        spectral-response
+
+    See Also
+    --------
+    pvlib.spectrum.spectral_responsivity_to_quantum_efficiency
+    """
+    if wavelength is None:
+        if hasattr(qe, "index"):  # true for pandas objects
+            # use reference to index values instead of index alone so
+            # sr / wavelength returns a series with the same name
+            wavelength = qe.index.array
+        else:
+            raise TypeError(
+                "'qe' must have an '.index' attribute"
+                + " or 'wavelength' must be provided"
+            )
+    spectral_responsivity = (
+        qe
+        * wavelength
+        / _PLANCK_BY_LIGHT_SPEED_OVER_ELEMENTAL_CHARGE_BY_BILLION
+    )
+    return spectral_responsivity
diff --git a/pvlib/tests/test_spectrum.py b/pvlib/tests/test_spectrum.py
index 793eaacfdf..9aa126a5a0 100644
--- a/pvlib/tests/test_spectrum.py
+++ b/pvlib/tests/test_spectrum.py
@@ -140,7 +140,7 @@ def test_get_am15g():
 
 def test_calc_spectral_mismatch_field(spectrl2_data):
     # test that the mismatch is calculated correctly with
-    # - default and custom reference sepctrum
+    # - default and custom reference spectrum
     # - single or multiple sun spectra
 
     # sample data
@@ -315,3 +315,91 @@ def test_spectral_factor_caballero_supplied_ambiguous():
     with pytest.raises(ValueError):
         spectrum.spectral_factor_caballero(1, 1, 1, module_type=None,
                                            coefficients=None)
+
+
+@pytest.fixture
+def sr_and_eqe_fixture():
+    df = pd.DataFrame(
+        columns=("wavelength", "quantum_efficiency", "spectral_response"),
+        data=[
+            # nm, [0,1], A/W
+            [300, 0.85, 0.205671370402405],
+            [350, 0.86, 0.242772872514211],
+            [400, 0.87, 0.280680929019753],
+            [450, 0.88, 0.319395539919029],
+            [500, 0.89, 0.358916705212040],
+            [550, 0.90, 0.399244424898786],
+            [600, 0.91, 0.440378698979267],
+            [650, 0.92, 0.482319527453483],
+            [700, 0.93, 0.525066910321434],
+            [750, 0.94, 0.568620847583119],
+            [800, 0.95, 0.612981339238540],
+            [850, 0.90, 0.617014111207215],
+            [900, 0.80, 0.580719163489143],
+            [950, 0.70, 0.536358671833723],
+            [1000, 0.6, 0.483932636240953],
+            [1050, 0.4, 0.338752845368667],
+        ],
+    )
+    df.set_index("wavelength", inplace=True)
+    return df
+
+
+def test_spectral_responsivity_to_quantum_efficiency(sr_and_eqe_fixture):
+    #- scalar type
+    qe = spectrum.spectral_responsivity_to_quantum_efficiency(
+        sr_and_eqe_fixture["spectral_response"].values[0],
+        sr_and_eqe_fixture.index.values[0],  # wavelength, nm
+    )
+    assert_approx_equal(qe, sr_and_eqe_fixture["quantum_efficiency"].values[0])
+    #- vector type
+    qe = spectrum.spectral_responsivity_to_quantum_efficiency(
+        sr_and_eqe_fixture["spectral_response"].values,
+        sr_and_eqe_fixture.index.values,  # wavelength, nm
+    )
+    assert_allclose(qe, sr_and_eqe_fixture["quantum_efficiency"])
+    #- pandas series type
+    # note: output Series' name should match the input
+    qe = spectrum.spectral_responsivity_to_quantum_efficiency(
+        sr_and_eqe_fixture["spectral_response"]
+    )
+    pd.testing.assert_series_equal(
+        qe, sr_and_eqe_fixture["quantum_efficiency"],
+        check_names=False  
+    )
+    assert qe.name == "spectral_response"
+    #- error on lack of wavelength parameter if no pandas obj. provided
+    with pytest.raises(TypeError, match="must have an '.index' attribute"):
+        _ = spectrum.spectral_responsivity_to_quantum_efficiency(
+            sr_and_eqe_fixture["spectral_response"].values
+        )
+
+
+def test_quantum_efficiency_to_spectral_responsivity(sr_and_eqe_fixture):
+    #- scalar type
+    sr = spectrum.quantum_efficiency_to_spectral_responsivity(
+        sr_and_eqe_fixture["quantum_efficiency"].values[0],
+        sr_and_eqe_fixture.index.values[0],  # wavelength, nm
+    )
+    assert_approx_equal(sr, sr_and_eqe_fixture["spectral_response"].values[0])
+    #- vector type
+    sr = spectrum.quantum_efficiency_to_spectral_responsivity(
+        sr_and_eqe_fixture["quantum_efficiency"].values,
+        sr_and_eqe_fixture.index.values,  # wavelength, nm
+    )
+    assert_allclose(sr, sr_and_eqe_fixture["spectral_response"])
+    #- pandas series type
+    # note: output Series' name should match the input
+    sr = spectrum.quantum_efficiency_to_spectral_responsivity(
+        sr_and_eqe_fixture["quantum_efficiency"]
+    )
+    pd.testing.assert_series_equal(
+        sr, sr_and_eqe_fixture["spectral_response"],
+        check_names=False  
+    )
+    assert sr.name == "quantum_efficiency"
+    #- error on lack of wavelength parameter if no pandas obj. provided
+    with pytest.raises(TypeError, match="must have an '.index' attribute"):
+        _ = spectrum.quantum_efficiency_to_spectral_responsivity(
+            sr_and_eqe_fixture["quantum_efficiency"].values
+        )

From 52a4752dce263f161560be587a06a159508bb175 Mon Sep 17 00:00:00 2001
From: echedey-ls <80125792+echedey-ls@users.noreply.github.com>
Date: Sun, 24 Mar 2024 13:31:38 +0100
Subject: [PATCH 02/17] Update v0.10.5.rst

---
 docs/sphinx/source/whatsnew/v0.10.5.rst | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/docs/sphinx/source/whatsnew/v0.10.5.rst b/docs/sphinx/source/whatsnew/v0.10.5.rst
index e7097ea5b4..096aa67c6a 100644
--- a/docs/sphinx/source/whatsnew/v0.10.5.rst
+++ b/docs/sphinx/source/whatsnew/v0.10.5.rst
@@ -11,6 +11,10 @@ Deprecations
 
 Enhancements
 ~~~~~~~~~~~~
+* Added :py:func:`pvlib.spectrum.spectral_responsivity_to_quantum_efficiency`
+  and :py:func:`pvlib.spectrum.quantum_efficiency_to_spectral_responsivity`
+  to convert quantum efficiencies into spectral responsivities and viceversa.
+  (:issue:`1963`, :pull:`TODO`)
 
 
 Bug fixes
@@ -31,3 +35,6 @@ Requirements
 
 Contributors
 ~~~~~~~~~~~~
+* Echedey Luis (:ghuser:`echedey-ls`)
+* Mark Mikofski (:ghuser:`mikofski`)
+* Mark Campanelli (:ghuser:`markcampanelli`)

From 8fcabde1fedb9432f1e46886053591a1a741631c Mon Sep 17 00:00:00 2001
From: echedey-ls <80125792+echedey-ls@users.noreply.github.com>
Date: Thu, 11 Apr 2024 18:53:35 +0200
Subject: [PATCH 03/17] Add docstring examples

---
 pvlib/spectrum/mismatch.py   | 48 ++++++++++++++++++++++++++++++++++++
 pvlib/tests/test_spectrum.py |  5 ++--
 2 files changed, 51 insertions(+), 2 deletions(-)

diff --git a/pvlib/spectrum/mismatch.py b/pvlib/spectrum/mismatch.py
index 500573efdf..98f8d83f7c 100644
--- a/pvlib/spectrum/mismatch.py
+++ b/pvlib/spectrum/mismatch.py
@@ -613,6 +613,30 @@ def spectral_responsivity_to_quantum_efficiency(sr, wavelength=None):
     - If ``wavelength`` is provided it will be used independently of the
       datatype of ``sr``.
 
+    Examples
+    --------
+    >>> import numpy as np
+    >>> from pvlib import spectrum
+    >>> wavelengths = np.array([350, 550, 750])
+    >>> spectral_response = np.array([0.25, 0.40, 0.57])
+    >>> quantum_efficiency = \
+    >>>     spectrum.spectral_responsivity_to_quantum_efficiency(
+    >>>         spectral_response, wavelengths
+    >>>     )
+    >>> quantum_efficiency
+    array([0.88560142, 0.90170326, 0.94227991])
+
+    >>> spectral_response_series = \
+    >>>     pd.Series(spectral_response, index=wavelengths, name="dataset")
+    >>> qe = spectrum.spectral_responsivity_to_quantum_efficiency(
+    >>>         spectral_response_series
+    >>>     )
+    >>> qe
+    350    0.885601
+    550    0.901703
+    750    0.942280
+    Name: dataset, dtype: float64
+
     References
     ----------
     .. [1] “Spectral Response,” PV Performance Modeling Collaborative (PVPMC).
@@ -676,6 +700,30 @@ def quantum_efficiency_to_spectral_responsivity(qe, wavelength=None):
     - If ``wavelength`` is provided it will be used independently of the
       datatype of ``qe``.
 
+    Examples
+    --------
+    >>> import numpy as np
+    >>> from pvlib import spectrum
+    >>> wavelengths = np.array([350, 550, 750])
+    >>> quantum_efficiency = np.array([0.86, 0.90, 0.94])
+    >>> spectral_response = \
+    >>>     spectrum.quantum_efficiency_to_spectral_responsivity(
+    >>>         quantum_efficiency, wavelengths
+    >>>     )
+    >>> spectral_response
+    array([0.24277287, 0.39924442, 0.56862085])
+
+    >>> quantum_efficiency_series = \
+    >>>     pd.Series(quantum_efficiency, index=wavelengths, name="dataset")
+    >>> sr = spectrum.quantum_efficiency_to_spectral_responsivity(
+    >>>         quantum_efficiency_series
+    >>>     )
+    >>> sr
+    350    0.242773
+    550    0.399244
+    750    0.568621
+    Name: dataset, dtype: float64
+
     References
     ----------
     .. [1] “Spectral Response,” PV Performance Modeling Collaborative (PVPMC).
diff --git a/pvlib/tests/test_spectrum.py b/pvlib/tests/test_spectrum.py
index 9aa126a5a0..3eee204af7 100644
--- a/pvlib/tests/test_spectrum.py
+++ b/pvlib/tests/test_spectrum.py
@@ -319,6 +319,7 @@ def test_spectral_factor_caballero_supplied_ambiguous():
 
 @pytest.fixture
 def sr_and_eqe_fixture():
+    # Just some arbitrary data for testing the conversion functions
     df = pd.DataFrame(
         columns=("wavelength", "quantum_efficiency", "spectral_response"),
         data=[
@@ -368,7 +369,7 @@ def test_spectral_responsivity_to_quantum_efficiency(sr_and_eqe_fixture):
         check_names=False  
     )
     assert qe.name == "spectral_response"
-    #- error on lack of wavelength parameter if no pandas obj. provided
+    #- error on lack of wavelength parameter if no pandas object is provided
     with pytest.raises(TypeError, match="must have an '.index' attribute"):
         _ = spectrum.spectral_responsivity_to_quantum_efficiency(
             sr_and_eqe_fixture["spectral_response"].values
@@ -398,7 +399,7 @@ def test_quantum_efficiency_to_spectral_responsivity(sr_and_eqe_fixture):
         check_names=False  
     )
     assert sr.name == "quantum_efficiency"
-    #- error on lack of wavelength parameter if no pandas obj. provided
+    #- error on lack of wavelength parameter if no pandas object is provided
     with pytest.raises(TypeError, match="must have an '.index' attribute"):
         _ = spectrum.quantum_efficiency_to_spectral_responsivity(
             sr_and_eqe_fixture["quantum_efficiency"].values

From 1b5be03176293da15e8bde9921e2fa21dafbc3da Mon Sep 17 00:00:00 2001
From: echedey-ls <80125792+echedey-ls@users.noreply.github.com>
Date: Tue, 7 May 2024 00:21:59 +0200
Subject: [PATCH 04/17] Update v0.11.0.rst

---
 docs/sphinx/source/whatsnew/v0.11.0.rst | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/docs/sphinx/source/whatsnew/v0.11.0.rst b/docs/sphinx/source/whatsnew/v0.11.0.rst
index 7ea847a6d9..440372d2be 100644
--- a/docs/sphinx/source/whatsnew/v0.11.0.rst
+++ b/docs/sphinx/source/whatsnew/v0.11.0.rst
@@ -15,6 +15,10 @@ Deprecations
 
 Enhancements
 ~~~~~~~~~~~~
+* Added conversion functions from spectral response :math:`[A/W]` to quantum
+  efficiency :math:`[unitless]` and vice versa. The conversion functions are
+  :py:func:`spectral_responsivity_to_quantum_efficiency` and :py:func:`quantum_efficiency_to_spectral_responsivity` respectively.
+  (:issue:`2040`, :pull:`2041`)
 
 
 Bug fixes
@@ -35,3 +39,4 @@ Requirements
 
 Contributors
 ~~~~~~~~~~~~
+* Mark Campanelli (:ghuser:`markcampanelli`)

From 3631830a5ce894b3f1ede93cf7a8a187898abddc Mon Sep 17 00:00:00 2001
From: echedey-ls <80125792+echedey-ls@users.noreply.github.com>
Date: Tue, 7 May 2024 00:32:55 +0200
Subject: [PATCH 05/17] Linter

---
 pvlib/tests/test_spectrum.py | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/pvlib/tests/test_spectrum.py b/pvlib/tests/test_spectrum.py
index 3eee204af7..e6f56c4070 100644
--- a/pvlib/tests/test_spectrum.py
+++ b/pvlib/tests/test_spectrum.py
@@ -347,19 +347,19 @@ def sr_and_eqe_fixture():
 
 
 def test_spectral_responsivity_to_quantum_efficiency(sr_and_eqe_fixture):
-    #- scalar type
+    # scalar type
     qe = spectrum.spectral_responsivity_to_quantum_efficiency(
         sr_and_eqe_fixture["spectral_response"].values[0],
         sr_and_eqe_fixture.index.values[0],  # wavelength, nm
     )
     assert_approx_equal(qe, sr_and_eqe_fixture["quantum_efficiency"].values[0])
-    #- vector type
+    # vector type
     qe = spectrum.spectral_responsivity_to_quantum_efficiency(
         sr_and_eqe_fixture["spectral_response"].values,
         sr_and_eqe_fixture.index.values,  # wavelength, nm
     )
     assert_allclose(qe, sr_and_eqe_fixture["quantum_efficiency"])
-    #- pandas series type
+    # pandas series type
     # note: output Series' name should match the input
     qe = spectrum.spectral_responsivity_to_quantum_efficiency(
         sr_and_eqe_fixture["spectral_response"]
@@ -369,7 +369,7 @@ def test_spectral_responsivity_to_quantum_efficiency(sr_and_eqe_fixture):
         check_names=False  
     )
     assert qe.name == "spectral_response"
-    #- error on lack of wavelength parameter if no pandas object is provided
+    # error on lack of wavelength parameter if no pandas object is provided
     with pytest.raises(TypeError, match="must have an '.index' attribute"):
         _ = spectrum.spectral_responsivity_to_quantum_efficiency(
             sr_and_eqe_fixture["spectral_response"].values
@@ -377,19 +377,19 @@ def test_spectral_responsivity_to_quantum_efficiency(sr_and_eqe_fixture):
 
 
 def test_quantum_efficiency_to_spectral_responsivity(sr_and_eqe_fixture):
-    #- scalar type
+    # scalar type
     sr = spectrum.quantum_efficiency_to_spectral_responsivity(
         sr_and_eqe_fixture["quantum_efficiency"].values[0],
         sr_and_eqe_fixture.index.values[0],  # wavelength, nm
     )
     assert_approx_equal(sr, sr_and_eqe_fixture["spectral_response"].values[0])
-    #- vector type
+    # vector type
     sr = spectrum.quantum_efficiency_to_spectral_responsivity(
         sr_and_eqe_fixture["quantum_efficiency"].values,
         sr_and_eqe_fixture.index.values,  # wavelength, nm
     )
     assert_allclose(sr, sr_and_eqe_fixture["spectral_response"])
-    #- pandas series type
+    # pandas series type
     # note: output Series' name should match the input
     sr = spectrum.quantum_efficiency_to_spectral_responsivity(
         sr_and_eqe_fixture["quantum_efficiency"]
@@ -399,7 +399,7 @@ def test_quantum_efficiency_to_spectral_responsivity(sr_and_eqe_fixture):
         check_names=False  
     )
     assert sr.name == "quantum_efficiency"
-    #- error on lack of wavelength parameter if no pandas object is provided
+    # error on lack of wavelength parameter if no pandas object is provided
     with pytest.raises(TypeError, match="must have an '.index' attribute"):
         _ = spectrum.quantum_efficiency_to_spectral_responsivity(
             sr_and_eqe_fixture["quantum_efficiency"].values

From 75a27d62fd36705df86fd2e5e9a68e52c44ac61e Mon Sep 17 00:00:00 2001
From: echedey-ls <80125792+echedey-ls@users.noreply.github.com>
Date: Tue, 7 May 2024 00:33:27 +0200
Subject: [PATCH 06/17] More linter xD

---
 pvlib/tests/test_spectrum.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/pvlib/tests/test_spectrum.py b/pvlib/tests/test_spectrum.py
index e6f56c4070..779276fdff 100644
--- a/pvlib/tests/test_spectrum.py
+++ b/pvlib/tests/test_spectrum.py
@@ -366,7 +366,7 @@ def test_spectral_responsivity_to_quantum_efficiency(sr_and_eqe_fixture):
     )
     pd.testing.assert_series_equal(
         qe, sr_and_eqe_fixture["quantum_efficiency"],
-        check_names=False  
+        check_names=False
     )
     assert qe.name == "spectral_response"
     # error on lack of wavelength parameter if no pandas object is provided
@@ -396,7 +396,7 @@ def test_quantum_efficiency_to_spectral_responsivity(sr_and_eqe_fixture):
     )
     pd.testing.assert_series_equal(
         sr, sr_and_eqe_fixture["spectral_response"],
-        check_names=False  
+        check_names=False
     )
     assert sr.name == "quantum_efficiency"
     # error on lack of wavelength parameter if no pandas object is provided

From b057d28ca1e3c36c5125b1c3930ff8fe6dd42ef4 Mon Sep 17 00:00:00 2001
From: echedey-ls <80125792+echedey-ls@users.noreply.github.com>
Date: Tue, 7 May 2024 00:37:32 +0200
Subject: [PATCH 07/17] Remove reference links from first sentence

Since it messes the links in the toc table.
---
 pvlib/spectrum/mismatch.py | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/pvlib/spectrum/mismatch.py b/pvlib/spectrum/mismatch.py
index a8a8bc8215..b7b624289c 100644
--- a/pvlib/spectrum/mismatch.py
+++ b/pvlib/spectrum/mismatch.py
@@ -584,13 +584,15 @@ def spectral_factor_caballero(precipitable_water, airmass_absolute, aod500,
 
 def spectral_responsivity_to_quantum_efficiency(sr, wavelength=None):
     """
-    Convert spectral responsivities to quantum efficiencies [1]_.
+    Convert spectral responsivities to quantum efficiencies.
     If ``wavelength`` is not provided, the spectral responsivity ``sr`` must be
     a :py:class:`pandas.Series` or :py:class:`pandas.DataFrame`, with the
     wavelengths in the index.
 
     Provide wavelengths in nanometers :math:`[nm]`.
 
+    Conversion is described in [1]_.
+
     .. versionadded:: 0.10.5
 
     Parameters
@@ -671,13 +673,15 @@ def spectral_responsivity_to_quantum_efficiency(sr, wavelength=None):
 
 def quantum_efficiency_to_spectral_responsivity(qe, wavelength=None):
     """
-    Convert quantum efficiencies to spectral responsivities [1]_.
+    Convert quantum efficiencies to spectral responsivities.
     If ``wavelength`` is not provided, the quantum efficiency ``qe`` must be
     a :py:class:`pandas.Series` or :py:class:`pandas.DataFrame`, with the
     wavelengths in the index.
 
     Provide wavelengths in nanometers :math:`[nm]`.
 
+    Conversion is described in [1]_.
+
     .. versionadded:: 0.10.5
 
     Parameters

From 27f160e8deeddcc2b4f0236146963a27b82f5e41 Mon Sep 17 00:00:00 2001
From: echedey-ls <80125792+echedey-ls@users.noreply.github.com>
Date: Fri, 10 May 2024 10:57:17 +0200
Subject: [PATCH 08/17] remove old whatsme entries

Co-Authored-By: Kevin Anderson <57452607+kandersolar@users.noreply.github.com>
---
 docs/sphinx/source/whatsnew/v0.10.5.rst | 14 --------------
 1 file changed, 14 deletions(-)

diff --git a/docs/sphinx/source/whatsnew/v0.10.5.rst b/docs/sphinx/source/whatsnew/v0.10.5.rst
index 5f7372403e..61e2eac5e5 100644
--- a/docs/sphinx/source/whatsnew/v0.10.5.rst
+++ b/docs/sphinx/source/whatsnew/v0.10.5.rst
@@ -1,20 +1,6 @@
 .. _whatsnew_01050:
 
 
-v0.10.5 (Anticipated June 2024)
--------------------------------
-
-
-Deprecations
-~~~~~~~~~~~~
-
-
-Enhancements
-~~~~~~~~~~~~
-* Added :py:func:`pvlib.spectrum.spectral_responsivity_to_quantum_efficiency`
-  and :py:func:`pvlib.spectrum.quantum_efficiency_to_spectral_responsivity`
-  to convert quantum efficiencies into spectral responsivities and viceversa.
-  (:issue:`1963`, :pull:`TODO`)
 v0.10.5 (May 6, 2024)
 ---------------------
 

From d7d9b81b78329ff90f493ca4642db8dc393fdd48 Mon Sep 17 00:00:00 2001
From: echedey-ls <80125792+echedey-ls@users.noreply.github.com>
Date: Fri, 10 May 2024 11:04:46 +0200
Subject: [PATCH 09/17] rename funcs and change versionadded's

Co-Authored-By: Kevin Anderson <57452607+kandersolar@users.noreply.github.com>
---
 .../effects_on_pv_system_output/spectrum.rst  |  4 +-
 docs/sphinx/source/whatsnew/v0.11.0.rst       |  4 +-
 pvlib/spectrum/__init__.py                    |  4 +-
 pvlib/spectrum/mismatch.py                    | 38 +++++++------------
 pvlib/tests/test_spectrum.py                  | 20 +++++-----
 5 files changed, 30 insertions(+), 40 deletions(-)

diff --git a/docs/sphinx/source/reference/effects_on_pv_system_output/spectrum.rst b/docs/sphinx/source/reference/effects_on_pv_system_output/spectrum.rst
index 9d2e4c51a5..fde3b170a9 100644
--- a/docs/sphinx/source/reference/effects_on_pv_system_output/spectrum.rst
+++ b/docs/sphinx/source/reference/effects_on_pv_system_output/spectrum.rst
@@ -13,5 +13,5 @@ Spectrum
    spectrum.spectral_factor_caballero
    spectrum.spectral_factor_firstsolar
    spectrum.spectral_factor_sapm
-   spectrum.spectral_responsivity_to_quantum_efficiency
-   spectrum.quantum_efficiency_to_spectral_responsivity
+   spectrum.sr_to_qe
+   spectrum.qe_to_sr
diff --git a/docs/sphinx/source/whatsnew/v0.11.0.rst b/docs/sphinx/source/whatsnew/v0.11.0.rst
index 440372d2be..0f93837c6a 100644
--- a/docs/sphinx/source/whatsnew/v0.11.0.rst
+++ b/docs/sphinx/source/whatsnew/v0.11.0.rst
@@ -17,8 +17,8 @@ Enhancements
 ~~~~~~~~~~~~
 * Added conversion functions from spectral response :math:`[A/W]` to quantum
   efficiency :math:`[unitless]` and vice versa. The conversion functions are
-  :py:func:`spectral_responsivity_to_quantum_efficiency` and :py:func:`quantum_efficiency_to_spectral_responsivity` respectively.
-  (:issue:`2040`, :pull:`2041`)
+  :py:func:`pvlib.spectrum.sr_to_qe` and :py:func:`pvlib.spectrum.qe_to_sr`
+  respectively. (:issue:`2040`, :pull:`2041`)
 
 
 Bug fixes
diff --git a/pvlib/spectrum/__init__.py b/pvlib/spectrum/__init__.py
index 00473e1708..0b9f7b03e9 100644
--- a/pvlib/spectrum/__init__.py
+++ b/pvlib/spectrum/__init__.py
@@ -6,6 +6,6 @@
     spectral_factor_caballero,
     spectral_factor_firstsolar,
     spectral_factor_sapm,
-    spectral_responsivity_to_quantum_efficiency,
-    quantum_efficiency_to_spectral_responsivity,
+    sr_to_qe,
+    qe_to_sr,
 )
diff --git a/pvlib/spectrum/mismatch.py b/pvlib/spectrum/mismatch.py
index b7b624289c..2982eb0b58 100644
--- a/pvlib/spectrum/mismatch.py
+++ b/pvlib/spectrum/mismatch.py
@@ -582,7 +582,7 @@ def spectral_factor_caballero(precipitable_water, airmass_absolute, aod500,
     return modifier
 
 
-def spectral_responsivity_to_quantum_efficiency(sr, wavelength=None):
+def sr_to_qe(sr, wavelength=None):
     """
     Convert spectral responsivities to quantum efficiencies.
     If ``wavelength`` is not provided, the spectral responsivity ``sr`` must be
@@ -593,7 +593,7 @@ def spectral_responsivity_to_quantum_efficiency(sr, wavelength=None):
 
     Conversion is described in [1]_.
 
-    .. versionadded:: 0.10.5
+    .. versionadded:: 0.11.0
 
     Parameters
     ----------
@@ -622,19 +622,14 @@ def spectral_responsivity_to_quantum_efficiency(sr, wavelength=None):
     >>> from pvlib import spectrum
     >>> wavelengths = np.array([350, 550, 750])
     >>> spectral_response = np.array([0.25, 0.40, 0.57])
-    >>> quantum_efficiency = \
-    >>>     spectrum.spectral_responsivity_to_quantum_efficiency(
-    >>>         spectral_response, wavelengths
-    >>>     )
-    >>> quantum_efficiency
+    >>> quantum_efficiency = spectrum.sr_to_qe(spectral_response, wavelengths)
+    >>> print(quantum_efficiency)
     array([0.88560142, 0.90170326, 0.94227991])
 
     >>> spectral_response_series = \
     >>>     pd.Series(spectral_response, index=wavelengths, name="dataset")
-    >>> qe = spectrum.spectral_responsivity_to_quantum_efficiency(
-    >>>         spectral_response_series
-    >>>     )
-    >>> qe
+    >>> qe = spectrum.sr_to_qe(spectral_response_series)
+    >>> print(qe)
     350    0.885601
     550    0.901703
     750    0.942280
@@ -651,7 +646,7 @@ def spectral_responsivity_to_quantum_efficiency(sr, wavelength=None):
 
     See Also
     --------
-    pvlib.spectrum.quantum_efficiency_to_spectral_responsivity
+    pvlib.spectrum.qe_to_sr
     """
     if wavelength is None:
         if hasattr(sr, "index"):  # true for pandas objects
@@ -671,7 +666,7 @@ def spectral_responsivity_to_quantum_efficiency(sr, wavelength=None):
     return quantum_efficiency
 
 
-def quantum_efficiency_to_spectral_responsivity(qe, wavelength=None):
+def qe_to_sr(qe, wavelength=None):
     """
     Convert quantum efficiencies to spectral responsivities.
     If ``wavelength`` is not provided, the quantum efficiency ``qe`` must be
@@ -682,7 +677,7 @@ def quantum_efficiency_to_spectral_responsivity(qe, wavelength=None):
 
     Conversion is described in [1]_.
 
-    .. versionadded:: 0.10.5
+    .. versionadded:: 0.11.0
 
     Parameters
     ----------
@@ -711,19 +706,14 @@ def quantum_efficiency_to_spectral_responsivity(qe, wavelength=None):
     >>> from pvlib import spectrum
     >>> wavelengths = np.array([350, 550, 750])
     >>> quantum_efficiency = np.array([0.86, 0.90, 0.94])
-    >>> spectral_response = \
-    >>>     spectrum.quantum_efficiency_to_spectral_responsivity(
-    >>>         quantum_efficiency, wavelengths
-    >>>     )
-    >>> spectral_response
+    >>> spectral_response = spectrum.qe_to_sr(quantum_efficiency, wavelengths)
+    >>> print(spectral_response)
     array([0.24277287, 0.39924442, 0.56862085])
 
     >>> quantum_efficiency_series = \
     >>>     pd.Series(quantum_efficiency, index=wavelengths, name="dataset")
-    >>> sr = spectrum.quantum_efficiency_to_spectral_responsivity(
-    >>>         quantum_efficiency_series
-    >>>     )
-    >>> sr
+    >>> sr = spectrum.qe_to_sr(quantum_efficiency_series)
+    >>> print(sr)
     350    0.242773
     550    0.399244
     750    0.568621
@@ -740,7 +730,7 @@ def quantum_efficiency_to_spectral_responsivity(qe, wavelength=None):
 
     See Also
     --------
-    pvlib.spectrum.spectral_responsivity_to_quantum_efficiency
+    pvlib.spectrum.sr_to_qe
     """
     if wavelength is None:
         if hasattr(qe, "index"):  # true for pandas objects
diff --git a/pvlib/tests/test_spectrum.py b/pvlib/tests/test_spectrum.py
index 779276fdff..979cc2d644 100644
--- a/pvlib/tests/test_spectrum.py
+++ b/pvlib/tests/test_spectrum.py
@@ -346,22 +346,22 @@ def sr_and_eqe_fixture():
     return df
 
 
-def test_spectral_responsivity_to_quantum_efficiency(sr_and_eqe_fixture):
+def test_sr_to_qe(sr_and_eqe_fixture):
     # scalar type
-    qe = spectrum.spectral_responsivity_to_quantum_efficiency(
+    qe = spectrum.sr_to_qe(
         sr_and_eqe_fixture["spectral_response"].values[0],
         sr_and_eqe_fixture.index.values[0],  # wavelength, nm
     )
     assert_approx_equal(qe, sr_and_eqe_fixture["quantum_efficiency"].values[0])
     # vector type
-    qe = spectrum.spectral_responsivity_to_quantum_efficiency(
+    qe = spectrum.sr_to_qe(
         sr_and_eqe_fixture["spectral_response"].values,
         sr_and_eqe_fixture.index.values,  # wavelength, nm
     )
     assert_allclose(qe, sr_and_eqe_fixture["quantum_efficiency"])
     # pandas series type
     # note: output Series' name should match the input
-    qe = spectrum.spectral_responsivity_to_quantum_efficiency(
+    qe = spectrum.sr_to_qe(
         sr_and_eqe_fixture["spectral_response"]
     )
     pd.testing.assert_series_equal(
@@ -371,27 +371,27 @@ def test_spectral_responsivity_to_quantum_efficiency(sr_and_eqe_fixture):
     assert qe.name == "spectral_response"
     # error on lack of wavelength parameter if no pandas object is provided
     with pytest.raises(TypeError, match="must have an '.index' attribute"):
-        _ = spectrum.spectral_responsivity_to_quantum_efficiency(
+        _ = spectrum.sr_to_qe(
             sr_and_eqe_fixture["spectral_response"].values
         )
 
 
-def test_quantum_efficiency_to_spectral_responsivity(sr_and_eqe_fixture):
+def test_qe_to_sr(sr_and_eqe_fixture):
     # scalar type
-    sr = spectrum.quantum_efficiency_to_spectral_responsivity(
+    sr = spectrum.qe_to_sr(
         sr_and_eqe_fixture["quantum_efficiency"].values[0],
         sr_and_eqe_fixture.index.values[0],  # wavelength, nm
     )
     assert_approx_equal(sr, sr_and_eqe_fixture["spectral_response"].values[0])
     # vector type
-    sr = spectrum.quantum_efficiency_to_spectral_responsivity(
+    sr = spectrum.qe_to_sr(
         sr_and_eqe_fixture["quantum_efficiency"].values,
         sr_and_eqe_fixture.index.values,  # wavelength, nm
     )
     assert_allclose(sr, sr_and_eqe_fixture["spectral_response"])
     # pandas series type
     # note: output Series' name should match the input
-    sr = spectrum.quantum_efficiency_to_spectral_responsivity(
+    sr = spectrum.qe_to_sr(
         sr_and_eqe_fixture["quantum_efficiency"]
     )
     pd.testing.assert_series_equal(
@@ -401,6 +401,6 @@ def test_quantum_efficiency_to_spectral_responsivity(sr_and_eqe_fixture):
     assert sr.name == "quantum_efficiency"
     # error on lack of wavelength parameter if no pandas object is provided
     with pytest.raises(TypeError, match="must have an '.index' attribute"):
-        _ = spectrum.quantum_efficiency_to_spectral_responsivity(
+        _ = spectrum.qe_to_sr(
             sr_and_eqe_fixture["quantum_efficiency"].values
         )

From 0b5ad4b07d1917b91efc36460e6c63f81a850680 Mon Sep 17 00:00:00 2001
From: echedey-ls <80125792+echedey-ls@users.noreply.github.com>
Date: Fri, 10 May 2024 11:05:43 +0200
Subject: [PATCH 10/17] Update v0.10.5.rst

Co-Authored-By: Kevin Anderson <57452607+kandersolar@users.noreply.github.com>
---
 docs/sphinx/source/whatsnew/v0.10.5.rst | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/docs/sphinx/source/whatsnew/v0.10.5.rst b/docs/sphinx/source/whatsnew/v0.10.5.rst
index 61e2eac5e5..00daed3a0f 100644
--- a/docs/sphinx/source/whatsnew/v0.10.5.rst
+++ b/docs/sphinx/source/whatsnew/v0.10.5.rst
@@ -33,9 +33,6 @@ Requirements
 
 Contributors
 ~~~~~~~~~~~~
-* Echedey Luis (:ghuser:`echedey-ls`)
-* Mark Mikofski (:ghuser:`mikofski`)
-* Mark Campanelli (:ghuser:`markcampanelli`)
 * Cliff Hansen (:ghuser:`cwhanse`)
 * :ghuser:`apct69`
 * Mark Mikofski (:ghuser:`mikofski`)

From 28ebce8daa37fec90b3ffada240457719df7d687 Mon Sep 17 00:00:00 2001
From: echedey-ls <80125792+echedey-ls@users.noreply.github.com>
Date: Tue, 21 May 2024 18:53:41 +0200
Subject: [PATCH 11/17] This is test driven development

---
 pvlib/tests/test_tools.py | 26 ++++++++++++++++++++++++++
 pvlib/tools.py            | 27 +++++++++++++++++++++++++++
 2 files changed, 53 insertions(+)

diff --git a/pvlib/tests/test_tools.py b/pvlib/tests/test_tools.py
index 583141a726..ddf56c53ef 100644
--- a/pvlib/tests/test_tools.py
+++ b/pvlib/tests/test_tools.py
@@ -3,6 +3,7 @@
 from pvlib import tools
 import numpy as np
 import pandas as pd
+from numpy.testing import assert_allclose
 
 
 @pytest.mark.parametrize('keys, input_dict, expected', [
@@ -120,3 +121,28 @@ def test_get_pandas_index(args, args_idx):
         assert index is None
     else:
         pd.testing.assert_index_equal(args[args_idx].index, index)
+
+
+@pytest.mark.parametrize('data_in,expected', [
+    (np.array([1, 2, 3, 4, 5]),
+     np.array([0.2, 0.4, 0.6, 0.8, 1])),
+    (np.array([[0, 1, 2], [0, 3, 6]]),
+     np.array([[0, 0.5, 1], [0, 0.5, 1]])),
+    (pd.Series([1, 2, 3, 4, 5]),
+     pd.Series([0.2, 0.4, 0.6, 0.8, 1])),
+    (pd.DataFrame({"a": [0, 1, 2], "b": [0, 2, 8]}),
+     pd.DataFrame({"a": [0, 0.5, 1], "b": [0, 0.25, 1]})),
+    # test with NaN and all zeroes
+    (np.array([1, 2, 3, 4, 5]),
+     np.array([0.2, 0.4, 0.6, 0.8, 1])),
+    (pd.DataFrame({"a": [0, np.nan, 1], "b": [0, 0, 0]}),
+     pd.DataFrame({"a": [0, np.nan, 1], "b": [np.nan]*3})),
+    # test with negative values
+    (np.array([1, 2, -3, 4, -5]),
+     np.array([0.2, 0.4, -0.6, 0.8, -1])),
+    (pd.Series([-2, np.nan, 1]),
+     pd.Series([-1, np.nan, 0.5])),
+])
+def test_normalize_max2one(data_in, expected):
+    result = tools.normalize_max2one(data_in)
+    assert_allclose(result, expected)
diff --git a/pvlib/tools.py b/pvlib/tools.py
index adf502a79d..3d766b6f72 100644
--- a/pvlib/tools.py
+++ b/pvlib/tools.py
@@ -507,3 +507,30 @@ def get_pandas_index(*args):
         (a.index for a in args if isinstance(a, (pd.DataFrame, pd.Series))),
         None
     )
+
+
+def normalize_max2one(a):
+    r"""
+    Normalize an array so that the largest absolute value is ±1.
+
+    Handles both numpy arrays and pandas objects.
+    On 2D arrays, normalization is row-wise.
+    On pandas DataFrame, normalization is column-wise.
+
+    If all values of row are 0, the array is set to NaNs.
+
+    Parameters
+    ----------
+    a : array-like
+        The array to normalize.
+
+    Returns
+    -------
+    array-like
+        The normalized array.
+    """
+    try:  # expect numpy array
+        res = a / np.max(np.absolute(a), axis=-1, keepdims=True)
+    except ValueError:  # fails for pandas objects
+        res = a.div(a.abs().max(axis=0, skipna=True))
+    return res

From 9bfa003923c02014b240e96958c2e2eaf5906064 Mon Sep 17 00:00:00 2001
From: echedey-ls <80125792+echedey-ls@users.noreply.github.com>
Date: Tue, 21 May 2024 22:26:27 +0200
Subject: [PATCH 12/17] apply normalization to functions

---
 pvlib/spectrum/mismatch.py   | 51 ++++++++++++++++++++++++++++++------
 pvlib/tests/test_spectrum.py | 24 ++++++++++++++---
 2 files changed, 64 insertions(+), 11 deletions(-)

diff --git a/pvlib/spectrum/mismatch.py b/pvlib/spectrum/mismatch.py
index 2982eb0b58..2877f306f7 100644
--- a/pvlib/spectrum/mismatch.py
+++ b/pvlib/spectrum/mismatch.py
@@ -3,6 +3,7 @@
 """
 
 import pvlib
+from pvlib.tools import normalize_max2one
 import numpy as np
 import pandas as pd
 import scipy.constants
@@ -582,7 +583,7 @@ def spectral_factor_caballero(precipitable_water, airmass_absolute, aod500,
     return modifier
 
 
-def sr_to_qe(sr, wavelength=None):
+def sr_to_qe(sr, wavelength=None, normalize=False):
     """
     Convert spectral responsivities to quantum efficiencies.
     If ``wavelength`` is not provided, the spectral responsivity ``sr`` must be
@@ -604,6 +605,12 @@ def sr_to_qe(sr, wavelength=None):
     wavelength : numeric, optional
         Points where spectral response is measured, in nanometers :math:`nm`.
 
+    normalize : bool, default False
+        If True, the quantum efficiency is normalized so that the maximum value
+        is 1.
+        For ``pandas.DataFrame``, normalization is done for each column.
+        For 2D arrays, normalization is done for each sub-array.
+
     Returns
     -------
     quantum_efficiency : numeric, same type as ``sr``
@@ -619,6 +626,7 @@ def sr_to_qe(sr, wavelength=None):
     Examples
     --------
     >>> import numpy as np
+    >>> import pandas as pd
     >>> from pvlib import spectrum
     >>> wavelengths = np.array([350, 550, 750])
     >>> spectral_response = np.array([0.25, 0.40, 0.57])
@@ -626,8 +634,7 @@ def sr_to_qe(sr, wavelength=None):
     >>> print(quantum_efficiency)
     array([0.88560142, 0.90170326, 0.94227991])
 
-    >>> spectral_response_series = \
-    >>>     pd.Series(spectral_response, index=wavelengths, name="dataset")
+    >>> spectral_response_series = pd.Series(spectral_response, index=wavelengths, name="dataset")
     >>> qe = spectrum.sr_to_qe(spectral_response_series)
     >>> print(qe)
     350    0.885601
@@ -635,6 +642,13 @@ def sr_to_qe(sr, wavelength=None):
     750    0.942280
     Name: dataset, dtype: float64
 
+    >>> qe = spectrum.sr_to_qe(spectral_response_series, normalize=True)
+    >>> print(qe)
+    350    0.939850
+    550    0.956938
+    750    1.000000
+    Name: dataset, dtype: float64
+
     References
     ----------
     .. [1] “Spectral Response,” PV Performance Modeling Collaborative (PVPMC).
@@ -647,7 +661,7 @@ def sr_to_qe(sr, wavelength=None):
     See Also
     --------
     pvlib.spectrum.qe_to_sr
-    """
+    """  # noqa: E501
     if wavelength is None:
         if hasattr(sr, "index"):  # true for pandas objects
             # use reference to index values instead of index alone so
@@ -663,10 +677,14 @@ def sr_to_qe(sr, wavelength=None):
         / wavelength
         * _PLANCK_BY_LIGHT_SPEED_OVER_ELEMENTAL_CHARGE_BY_BILLION
     )
+
+    if normalize:
+        quantum_efficiency = normalize_max2one(quantum_efficiency)
+
     return quantum_efficiency
 
 
-def qe_to_sr(qe, wavelength=None):
+def qe_to_sr(qe, wavelength=None, normalize=False):
     """
     Convert quantum efficiencies to spectral responsivities.
     If ``wavelength`` is not provided, the quantum efficiency ``qe`` must be
@@ -688,6 +706,12 @@ def qe_to_sr(qe, wavelength=None):
     wavelength : numeric, optional
         Points where quantum efficiency is measured, in nanometers :math:`nm`.
 
+    normalize : bool, default False
+        If True, the spectral response is normalized so that the maximum value
+        is 1.
+        For ``pandas.DataFrame``, normalization is done for each column.
+        For 2D arrays, normalization is done for each sub-array.
+
     Returns
     -------
     spectral_response : numeric, same type as ``qe``
@@ -703,6 +727,7 @@ def qe_to_sr(qe, wavelength=None):
     Examples
     --------
     >>> import numpy as np
+    >>> import pandas as pd
     >>> from pvlib import spectrum
     >>> wavelengths = np.array([350, 550, 750])
     >>> quantum_efficiency = np.array([0.86, 0.90, 0.94])
@@ -710,8 +735,7 @@ def qe_to_sr(qe, wavelength=None):
     >>> print(spectral_response)
     array([0.24277287, 0.39924442, 0.56862085])
 
-    >>> quantum_efficiency_series = \
-    >>>     pd.Series(quantum_efficiency, index=wavelengths, name="dataset")
+    >>> quantum_efficiency_series = pd.Series(quantum_efficiency, index=wavelengths, name="dataset")
     >>> sr = spectrum.qe_to_sr(quantum_efficiency_series)
     >>> print(sr)
     350    0.242773
@@ -719,6 +743,13 @@ def qe_to_sr(qe, wavelength=None):
     750    0.568621
     Name: dataset, dtype: float64
 
+    >>> sr = spectrum.qe_to_sr(quantum_efficiency_series, normalize=True)
+    >>> print(sr)
+    350    0.426950
+    550    0.702128
+    750    1.000000
+    Name: dataset, dtype: float64
+
     References
     ----------
     .. [1] “Spectral Response,” PV Performance Modeling Collaborative (PVPMC).
@@ -731,7 +762,7 @@ def qe_to_sr(qe, wavelength=None):
     See Also
     --------
     pvlib.spectrum.sr_to_qe
-    """
+    """  # noqa: E501
     if wavelength is None:
         if hasattr(qe, "index"):  # true for pandas objects
             # use reference to index values instead of index alone so
@@ -747,4 +778,8 @@ def qe_to_sr(qe, wavelength=None):
         * wavelength
         / _PLANCK_BY_LIGHT_SPEED_OVER_ELEMENTAL_CHARGE_BY_BILLION
     )
+
+    if normalize:
+        spectral_responsivity = normalize_max2one(spectral_responsivity)
+
     return spectral_responsivity
diff --git a/pvlib/tests/test_spectrum.py b/pvlib/tests/test_spectrum.py
index 979cc2d644..2cb9d07c22 100644
--- a/pvlib/tests/test_spectrum.py
+++ b/pvlib/tests/test_spectrum.py
@@ -369,11 +369,19 @@ def test_sr_to_qe(sr_and_eqe_fixture):
         check_names=False
     )
     assert qe.name == "spectral_response"
+    # series normalization
+    qe = spectrum.sr_to_qe(
+        sr_and_eqe_fixture["spectral_response"] * 10, normalize=True
+    )
+    pd.testing.assert_series_equal(
+        qe,
+        sr_and_eqe_fixture["quantum_efficiency"]
+        / max(sr_and_eqe_fixture["quantum_efficiency"]),
+        check_names=False,
+    )
     # error on lack of wavelength parameter if no pandas object is provided
     with pytest.raises(TypeError, match="must have an '.index' attribute"):
-        _ = spectrum.sr_to_qe(
-            sr_and_eqe_fixture["spectral_response"].values
-        )
+        _ = spectrum.sr_to_qe(sr_and_eqe_fixture["spectral_response"].values)
 
 
 def test_qe_to_sr(sr_and_eqe_fixture):
@@ -399,6 +407,16 @@ def test_qe_to_sr(sr_and_eqe_fixture):
         check_names=False
     )
     assert sr.name == "quantum_efficiency"
+    # series normalization
+    sr = spectrum.qe_to_sr(
+        sr_and_eqe_fixture["quantum_efficiency"] * 10, normalize=True
+    )
+    pd.testing.assert_series_equal(
+        sr,
+        sr_and_eqe_fixture["spectral_response"]
+        / max(sr_and_eqe_fixture["spectral_response"]),
+        check_names=False,
+    )
     # error on lack of wavelength parameter if no pandas object is provided
     with pytest.raises(TypeError, match="must have an '.index' attribute"):
         _ = spectrum.qe_to_sr(

From 4d6b44078e2ad6672b187c4792dffc2338504263 Mon Sep 17 00:00:00 2001
From: echedey-ls <80125792+echedey-ls@users.noreply.github.com>
Date: Sat, 25 May 2024 01:27:20 +0200
Subject: [PATCH 13/17] Update test_spectrum.py

Co-Authored-By: Kevin Anderson <57452607+kandersolar@users.noreply.github.com>
---
 pvlib/tests/test_spectrum.py | 21 +++++++++------------
 1 file changed, 9 insertions(+), 12 deletions(-)

diff --git a/pvlib/tests/test_spectrum.py b/pvlib/tests/test_spectrum.py
index 2cb9d07c22..7b86cb713e 100644
--- a/pvlib/tests/test_spectrum.py
+++ b/pvlib/tests/test_spectrum.py
@@ -347,12 +347,6 @@ def sr_and_eqe_fixture():
 
 
 def test_sr_to_qe(sr_and_eqe_fixture):
-    # scalar type
-    qe = spectrum.sr_to_qe(
-        sr_and_eqe_fixture["spectral_response"].values[0],
-        sr_and_eqe_fixture.index.values[0],  # wavelength, nm
-    )
-    assert_approx_equal(qe, sr_and_eqe_fixture["quantum_efficiency"].values[0])
     # vector type
     qe = spectrum.sr_to_qe(
         sr_and_eqe_fixture["spectral_response"].values,
@@ -385,12 +379,6 @@ def test_sr_to_qe(sr_and_eqe_fixture):
 
 
 def test_qe_to_sr(sr_and_eqe_fixture):
-    # scalar type
-    sr = spectrum.qe_to_sr(
-        sr_and_eqe_fixture["quantum_efficiency"].values[0],
-        sr_and_eqe_fixture.index.values[0],  # wavelength, nm
-    )
-    assert_approx_equal(sr, sr_and_eqe_fixture["spectral_response"].values[0])
     # vector type
     sr = spectrum.qe_to_sr(
         sr_and_eqe_fixture["quantum_efficiency"].values,
@@ -422,3 +410,12 @@ def test_qe_to_sr(sr_and_eqe_fixture):
         _ = spectrum.qe_to_sr(
             sr_and_eqe_fixture["quantum_efficiency"].values
         )
+
+
+def test_qe_and_sr_reciprocal_conversion(sr_and_eqe_fixture):
+    # test that the conversion functions are reciprocal
+    qe = spectrum.sr_to_qe(sr_and_eqe_fixture["spectral_response"])
+    sr = spectrum.qe_to_sr(qe)
+    assert_allclose(sr, sr_and_eqe_fixture["spectral_response"])
+    qe = spectrum.sr_to_qe(sr)
+    assert_allclose(qe, sr_and_eqe_fixture["quantum_efficiency"])

From 0b00fb74f095b7a82b52654256eaed55f20e32da Mon Sep 17 00:00:00 2001
From: echedey-ls <80125792+echedey-ls@users.noreply.github.com>
Date: Sat, 25 May 2024 01:28:56 +0200
Subject: [PATCH 14/17] Update test_tools.py

Co-Authored-By: Kevin Anderson <57452607+kandersolar@users.noreply.github.com>
---
 pvlib/tests/test_tools.py | 2 --
 1 file changed, 2 deletions(-)

diff --git a/pvlib/tests/test_tools.py b/pvlib/tests/test_tools.py
index ddf56c53ef..eb9e65c895 100644
--- a/pvlib/tests/test_tools.py
+++ b/pvlib/tests/test_tools.py
@@ -133,8 +133,6 @@ def test_get_pandas_index(args, args_idx):
     (pd.DataFrame({"a": [0, 1, 2], "b": [0, 2, 8]}),
      pd.DataFrame({"a": [0, 0.5, 1], "b": [0, 0.25, 1]})),
     # test with NaN and all zeroes
-    (np.array([1, 2, 3, 4, 5]),
-     np.array([0.2, 0.4, 0.6, 0.8, 1])),
     (pd.DataFrame({"a": [0, np.nan, 1], "b": [0, 0, 0]}),
      pd.DataFrame({"a": [0, np.nan, 1], "b": [np.nan]*3})),
     # test with negative values

From 8c30356bfb08eb3736817275dee565b6b58f2766 Mon Sep 17 00:00:00 2001
From: echedey-ls <80125792+echedey-ls@users.noreply.github.com>
Date: Sat, 25 May 2024 01:32:09 +0200
Subject: [PATCH 15/17] Units formatting

Co-Authored-By: Kevin Anderson <57452607+kandersolar@users.noreply.github.com>
Co-Authored-By: Adam R. Jensen <39184289+AdamRJensen@users.noreply.github.com>
---
 pvlib/spectrum/mismatch.py | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/pvlib/spectrum/mismatch.py b/pvlib/spectrum/mismatch.py
index b14daf5730..7acb5a5d88 100644
--- a/pvlib/spectrum/mismatch.py
+++ b/pvlib/spectrum/mismatch.py
@@ -590,7 +590,7 @@ def sr_to_qe(sr, wavelength=None, normalize=False):
     a :py:class:`pandas.Series` or :py:class:`pandas.DataFrame`, with the
     wavelengths in the index.
 
-    Provide wavelengths in nanometers :math:`[nm]`.
+    Provide wavelengths in nanometers, [nm].
 
     Conversion is described in [1]_.
 
@@ -599,11 +599,11 @@ def sr_to_qe(sr, wavelength=None, normalize=False):
     Parameters
     ----------
     sr : numeric, pandas.Series or pandas.DataFrame
-        Spectral response.
-        Index must be the wavelength in nanometers :math:`nm`.
+        Spectral response, [A/W].
+        Index must be the wavelength in nanometers, [nm].
 
     wavelength : numeric, optional
-        Points where spectral response is measured, in nanometers :math:`nm`.
+        Points where spectral response is measured, in nanometers, [nm].
 
     normalize : bool, default False
         If True, the quantum efficiency is normalized so that the maximum value
@@ -614,7 +614,7 @@ def sr_to_qe(sr, wavelength=None, normalize=False):
     Returns
     -------
     quantum_efficiency : numeric, same type as ``sr``
-        Quantum efficiency in the interval :math:`[0, 1]`.
+        Quantum efficiency, in the interval [0, 1].
 
     Notes
     -----
@@ -691,7 +691,7 @@ def qe_to_sr(qe, wavelength=None, normalize=False):
     a :py:class:`pandas.Series` or :py:class:`pandas.DataFrame`, with the
     wavelengths in the index.
 
-    Provide wavelengths in nanometers :math:`[nm]`.
+    Provide wavelengths in nanometers, [nm].
 
     Conversion is described in [1]_.
 
@@ -701,10 +701,10 @@ def qe_to_sr(qe, wavelength=None, normalize=False):
     ----------
     qe : numeric, pandas.Series or pandas.DataFrame
         Quantum efficiency.
-        If pandas subtype, index must be the wavelength in nanometers.
+        If pandas subtype, index must be the wavelength in nanometers, [nm].
 
     wavelength : numeric, optional
-        Points where quantum efficiency is measured, in nanometers :math:`nm`.
+        Points where quantum efficiency is measured, in nanometers, [nm].
 
     normalize : bool, default False
         If True, the spectral response is normalized so that the maximum value
@@ -715,7 +715,7 @@ def qe_to_sr(qe, wavelength=None, normalize=False):
     Returns
     -------
     spectral_response : numeric, same type as ``qe``
-        Spectral response in :math:`A/W`.
+        Spectral response, [A/W].
 
     Notes
     -----

From 606e9b6a36d4b6af65a9aebdcd5fcb3bd54004b3 Mon Sep 17 00:00:00 2001
From: echedey-ls <80125792+echedey-ls@users.noreply.github.com>
Date: Sat, 25 May 2024 01:33:19 +0200
Subject: [PATCH 16/17] Links

Co-Authored-By: Kevin Anderson <57452607+kandersolar@users.noreply.github.com>
---
 pvlib/spectrum/mismatch.py | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/pvlib/spectrum/mismatch.py b/pvlib/spectrum/mismatch.py
index 7acb5a5d88..e3f434f99c 100644
--- a/pvlib/spectrum/mismatch.py
+++ b/pvlib/spectrum/mismatch.py
@@ -652,11 +652,9 @@ def sr_to_qe(sr, wavelength=None, normalize=False):
     References
     ----------
     .. [1] “Spectral Response,” PV Performance Modeling Collaborative (PVPMC).
-        https://pvpmc.sandia.gov/modeling-guide/2-dc-module-iv/
-        effective-irradiance/spectral-response/
+        https://pvpmc.sandia.gov/modeling-guide/2-dc-module-iv/effective-irradiance/spectral-response/
     .. [2] “Spectral Response | PVEducation,” www.pveducation.org.
-        https://www.pveducation.org/pvcdrom/solar-cell-operation/
-        spectral-response
+        https://www.pveducation.org/pvcdrom/solar-cell-operation/spectral-response
 
     See Also
     --------
@@ -753,11 +751,9 @@ def qe_to_sr(qe, wavelength=None, normalize=False):
     References
     ----------
     .. [1] “Spectral Response,” PV Performance Modeling Collaborative (PVPMC).
-        https://pvpmc.sandia.gov/modeling-guide/2-dc-module-iv/
-        effective-irradiance/spectral-response/
+        https://pvpmc.sandia.gov/modeling-guide/2-dc-module-iv/effective-irradiance/spectral-response/
     .. [2] “Spectral Response | PVEducation,” www.pveducation.org.
-        https://www.pveducation.org/pvcdrom/solar-cell-operation/
-        spectral-response
+        https://www.pveducation.org/pvcdrom/solar-cell-operation/spectral-response
 
     See Also
     --------

From 83d875ef3cf3fb7bcb367e3ac0e5dd42bf73adb2 Mon Sep 17 00:00:00 2001
From: echedey-ls <80125792+echedey-ls@users.noreply.github.com>
Date: Sat, 25 May 2024 02:09:01 +0200
Subject: [PATCH 17/17] I'm obsessed with math mode

---
 docs/sphinx/source/whatsnew/v0.11.0.rst | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/docs/sphinx/source/whatsnew/v0.11.0.rst b/docs/sphinx/source/whatsnew/v0.11.0.rst
index 4fda536780..2f056cd3e4 100644
--- a/docs/sphinx/source/whatsnew/v0.11.0.rst
+++ b/docs/sphinx/source/whatsnew/v0.11.0.rst
@@ -19,8 +19,8 @@ Enhancements
   shade perpendicular to ``axis_azimuth``. The function is applicable to both
   fixed-tilt and one-axis tracking systems.
   (:issue:`1689`, :pull:`1725`, :pull:`1962`)
-* Added conversion functions from spectral response :math:`[A/W]` to quantum
-  efficiency :math:`[unitless]` and vice versa. The conversion functions are
+* Added conversion functions from spectral response ([A/W]) to quantum
+  efficiency ([unitless]) and vice versa. The conversion functions are
   :py:func:`pvlib.spectrum.sr_to_qe` and :py:func:`pvlib.spectrum.qe_to_sr`
   respectively. (:issue:`2040`, :pull:`2041`)