From a6be60afa8023c3a7857414fb9f1cf77e0c8fb21 Mon Sep 17 00:00:00 2001
From: Lakshya Garg <72099449+Lakshyadevelops@users.noreply.github.com>
Date: Fri, 24 Mar 2023 02:02:41 +0530
Subject: [PATCH 01/16] added pvl_louche

---
 pvlib/irradiance.py            | 48 ++++++++++++++++++++++++++++++++++
 pvlib/tests/test_irradiance.py | 15 +++++++++++
 2 files changed, 63 insertions(+)

diff --git a/pvlib/irradiance.py b/pvlib/irradiance.py
index 83527c7604..5ff68ccc8e 100644
--- a/pvlib/irradiance.py
+++ b/pvlib/irradiance.py
@@ -3117,3 +3117,51 @@ def complete_irradiance(solar_zenith,
                                      'dhi': dhi,
                                      'dni': dni})
     return component_sum_df
+
+
+def pvl_louche(ghi, zenith, datetime_or_doy):
+    """
+    Determine DNI and GHI from GHI using louche model.
+
+    Parameters
+    ----------
+    ghi : Series
+        Global horizontal irradiance.
+
+    zenith : Series
+        True (not refraction-corrected) zenith angles in decimal
+        degrees. Angles must be >=0 and <=180.
+
+    datetime_or_doy : numeric, pandas.DatetimeIndex
+        Day of year or array of days of year e.g.
+        pd.DatetimeIndex.dayofyear, or pd.DatetimeIndex.
+
+    Returns
+    -------
+    dni : Series
+        The modeled direct normal irradiance.
+
+    dhi : Series
+        The modeled diffused horizontal irradiance
+
+    kt : Series
+        Clearness index
+
+    References
+    -------
+    .. [1] Louche A, Notton G, Poggi P, Simmonnot G. Correlations for direct normal and global horizontal irradiation on French Mediterranean site. Solar Energy 1991;46:261-6
+
+    """
+    # this is the I0 calculation from the reference
+    # SSC uses solar constant = 1366.1
+    I0 = get_extra_radiation(datetime_or_doy)
+
+    I0h = I0*tools.cosd(zenith)
+    Kt = ghi/I0h
+    pd.Series.clip(Kt, 0, inplace=True)
+    kb = -10.627*Kt**5 + 15.307*Kt**4 - 5.205 * \
+        Kt**3 + 0.994*Kt**2 - 0.059*Kt + 0.002
+    dni = kb*I0
+    dhi = ghi-dni*tools.cosd(zenith)
+
+    return dni, dhi, Kt
diff --git a/pvlib/tests/test_irradiance.py b/pvlib/tests/test_irradiance.py
index cffdd23e40..b39b1e432d 100644
--- a/pvlib/tests/test_irradiance.py
+++ b/pvlib/tests/test_irradiance.py
@@ -1203,3 +1203,18 @@ def test_complete_irradiance():
                                        dhi=None,
                                        dni=i.dni,
                                        dni_clear=clearsky.dni)
+
+
+def test_pvl_louche():
+    times = pd.DatetimeIndex(['2016-07-19 06:11:00'], tz='America/Phoenix')
+    out_dni,out_dhi,out_kt = irradiance.pvl_louche(ghi=1.0, zenith=89.99,
+                          datetime_or_doy=times)
+    expected_dni=pd.Series(np.array([0.00000000e+00]),index=times)
+    # expected_dhi=pd.Series(np.array([8.72544336e+02]),index=times)
+    expected_kt=pd.Series(np.array([1.16046346e-02]),index=times)
+    assert_series_equal(out_dni,expected_dni)
+    # assert_series_equal(out_dhi,expected_dhi)
+    assert_series_equal(out_kt,expected_kt)
+
+
+    
\ No newline at end of file

From 125a6ad2d036b3266f829c6d816b4ad555813c41 Mon Sep 17 00:00:00 2001
From: Lakshya Garg <72099449+Lakshyadevelops@users.noreply.github.com>
Date: Fri, 24 Mar 2023 02:09:13 +0530
Subject: [PATCH 02/16] stickler

---
 pvlib/tests/test_irradiance.py | 24 +++++++++++++-----------
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/pvlib/tests/test_irradiance.py b/pvlib/tests/test_irradiance.py
index b39b1e432d..e7f456c4e6 100644
--- a/pvlib/tests/test_irradiance.py
+++ b/pvlib/tests/test_irradiance.py
@@ -246,6 +246,7 @@ def test_haydavies_components(irrad_data, ephem_data, dni_et):
     assert_allclose(result['horizon'], expected['horizon'][-1], atol=1e-4)
     assert isinstance(result, dict)
 
+
 def test_reindl(irrad_data, ephem_data, dni_et):
     result = irradiance.reindl(
         40, 180, irrad_data['dhi'], irrad_data['dni'], irrad_data['ghi'],
@@ -903,8 +904,12 @@ def test_dirindex(times):
     assert np.allclose(out, expected_out, rtol=tolerance, atol=0,
                        equal_nan=True)
     tol_dirint = 0.2
-    assert np.allclose(out.values, dirint_close_values, rtol=tol_dirint, atol=0,
-                       equal_nan=True)
+    assert np.allclose(
+        out.values,
+        dirint_close_values,
+        rtol=tol_dirint,
+        atol=0,
+        equal_nan=True)
 
 
 def test_dirindex_min_cos_zenith_max_zenith():
@@ -1207,14 +1212,11 @@ def test_complete_irradiance():
 
 def test_pvl_louche():
     times = pd.DatetimeIndex(['2016-07-19 06:11:00'], tz='America/Phoenix')
-    out_dni,out_dhi,out_kt = irradiance.pvl_louche(ghi=1.0, zenith=89.99,
-                          datetime_or_doy=times)
-    expected_dni=pd.Series(np.array([0.00000000e+00]),index=times)
+    out_dni, out_dhi, out_kt = irradiance.pvl_louche(ghi=1.0, zenith=89.99,
+                                                     datetime_or_doy=times)
+    expected_dni = pd.Series(np.array([0.00000000e+00]), index=times)
     # expected_dhi=pd.Series(np.array([8.72544336e+02]),index=times)
-    expected_kt=pd.Series(np.array([1.16046346e-02]),index=times)
-    assert_series_equal(out_dni,expected_dni)
+    expected_kt = pd.Series(np.array([1.16046346e-02]), index=times)
+    assert_series_equal(out_dni, expected_dni)
     # assert_series_equal(out_dhi,expected_dhi)
-    assert_series_equal(out_kt,expected_kt)
-
-
-    
\ No newline at end of file
+    assert_series_equal(out_kt, expected_kt)

From d0cb26d2d4faea04ba49ccedba5398efb8fd5642 Mon Sep 17 00:00:00 2001
From: Lakshya Garg <72099449+Lakshyadevelops@users.noreply.github.com>
Date: Tue, 28 Mar 2023 03:12:51 +0530
Subject: [PATCH 03/16] add tests

---
 pvlib/irradiance.py            | 44 +++++++++++++++++++++++-----------
 pvlib/tests/test_irradiance.py | 25 ++++++++++++-------
 2 files changed, 46 insertions(+), 23 deletions(-)

diff --git a/pvlib/irradiance.py b/pvlib/irradiance.py
index 5ff68ccc8e..81b3f5ae55 100644
--- a/pvlib/irradiance.py
+++ b/pvlib/irradiance.py
@@ -3119,14 +3119,14 @@ def complete_irradiance(solar_zenith,
     return component_sum_df
 
 
-def pvl_louche(ghi, zenith, datetime_or_doy):
+def pvl_louche(ghi, solar_zenith, datetime_or_doy):
     """
     Determine DNI and GHI from GHI using louche model.
 
     Parameters
     ----------
     ghi : Series
-        Global horizontal irradiance.
+        Global horizontal irradiance. [W/m^2]
 
     zenith : Series
         True (not refraction-corrected) zenith angles in decimal
@@ -3135,33 +3135,49 @@ def pvl_louche(ghi, zenith, datetime_or_doy):
     datetime_or_doy : numeric, pandas.DatetimeIndex
         Day of year or array of days of year e.g.
         pd.DatetimeIndex.dayofyear, or pd.DatetimeIndex.
-
+        
     Returns
     -------
-    dni : Series
-        The modeled direct normal irradiance.
-
-    dhi : Series
-        The modeled diffused horizontal irradiance
-
-    kt : Series
-        Clearness index
+    data: OrderedDict or DataFrame
+        Contains the following keys/columns:
+            
+            * ``dni``: the modeled direct normal irradiance in W/m^2.
+            * ``dhi``: the modeled diffuse horizontal irradiance in
+              W/m^2.
+            * ``kt``: Ratio of global to extraterrestrial irradiance
+              on a horizontal plane.
 
     References
     -------
     .. [1] Louche A, Notton G, Poggi P, Simmonnot G. Correlations for direct normal and global horizontal irradiation on French Mediterranean site. Solar Energy 1991;46:261-6
 
     """
+    bool=np.logical_or(solar_zenith>180,solar_zenith < 0)
+    solar_zenith=np.where(bool,np.NaN,solar_zenith)
+
+    if np.isscalar(datetime_or_doy):
+        bool=(np.any(datetime_or_doy>366 or datetime_or_doy < 1,axis=0))
+        print(bool)
+        datetime_or_doy=np.where(bool,np.NaN,datetime_or_doy)
+
     # this is the I0 calculation from the reference
     # SSC uses solar constant = 1366.1
     I0 = get_extra_radiation(datetime_or_doy)
 
-    I0h = I0*tools.cosd(zenith)
+    I0h = I0*tools.cosd(solar_zenith)
     Kt = ghi/I0h
     pd.Series.clip(Kt, 0, inplace=True)
     kb = -10.627*Kt**5 + 15.307*Kt**4 - 5.205 * \
         Kt**3 + 0.994*Kt**2 - 0.059*Kt + 0.002
     dni = kb*I0
-    dhi = ghi-dni*tools.cosd(zenith)
+    dhi = ghi-dni*tools.cosd(solar_zenith)
 
-    return dni, dhi, Kt
+    data=OrderedDict()
+    data['dni']=dni
+    data['dhi']=dhi
+    data['kt']=Kt
+
+    if isinstance(datetime_or_doy, pd.DatetimeIndex):
+        data = pd.DataFrame(data, index=datetime_or_doy)
+
+    return data
diff --git a/pvlib/tests/test_irradiance.py b/pvlib/tests/test_irradiance.py
index e7f456c4e6..0c721cd2eb 100644
--- a/pvlib/tests/test_irradiance.py
+++ b/pvlib/tests/test_irradiance.py
@@ -1211,12 +1211,19 @@ def test_complete_irradiance():
 
 
 def test_pvl_louche():
-    times = pd.DatetimeIndex(['2016-07-19 06:11:00'], tz='America/Phoenix')
-    out_dni, out_dhi, out_kt = irradiance.pvl_louche(ghi=1.0, zenith=89.99,
-                                                     datetime_or_doy=times)
-    expected_dni = pd.Series(np.array([0.00000000e+00]), index=times)
-    # expected_dhi=pd.Series(np.array([8.72544336e+02]),index=times)
-    expected_kt = pd.Series(np.array([1.16046346e-02]), index=times)
-    assert_series_equal(out_dni, expected_dni)
-    # assert_series_equal(out_dhi,expected_dhi)
-    assert_series_equal(out_kt, expected_kt)
+    
+    index = pd.DatetimeIndex(['20190101']*3 + ['20190620']*3)
+    ghi = pd.Series([0, 50, 1000, 1000, 1000, 1000], index=index)
+    zenith = pd.Series([120, 85, 10, 10, 182, -2], index=index)
+    expected = pd.DataFrame(np.array(
+        [[2.827964,     1.413982,        0.000000],
+         [130.089669, 38.661938, 0.405724],
+         [828.498650, 184.088106, 0.718133],
+         [887.407348, 126.074364, 0.768214],
+         [np.NaN, np.NaN, np.NaN],
+         [np.NaN, np.NaN, np.NaN]]),
+        columns=['dni', 'dhi', 'kt'], index=index)
+
+    out = irradiance.pvl_louche(ghi, zenith, index)
+
+    assert np.allclose(out, expected)

From f790fb3a19085390780af43649d0abdec560e996 Mon Sep 17 00:00:00 2001
From: Lakshya Garg <72099449+Lakshyadevelops@users.noreply.github.com>
Date: Tue, 28 Mar 2023 03:58:40 +0530
Subject: [PATCH 04/16] stickler

---
 pvlib/irradiance.py            | 20 ++++++++++----------
 pvlib/tests/test_irradiance.py |  6 +++---
 2 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/pvlib/irradiance.py b/pvlib/irradiance.py
index 81b3f5ae55..b7cc47cfc7 100644
--- a/pvlib/irradiance.py
+++ b/pvlib/irradiance.py
@@ -3135,12 +3135,12 @@ def pvl_louche(ghi, solar_zenith, datetime_or_doy):
     datetime_or_doy : numeric, pandas.DatetimeIndex
         Day of year or array of days of year e.g.
         pd.DatetimeIndex.dayofyear, or pd.DatetimeIndex.
-        
+
     Returns
     -------
     data: OrderedDict or DataFrame
         Contains the following keys/columns:
-            
+
             * ``dni``: the modeled direct normal irradiance in W/m^2.
             * ``dhi``: the modeled diffuse horizontal irradiance in
               W/m^2.
@@ -3152,13 +3152,13 @@ def pvl_louche(ghi, solar_zenith, datetime_or_doy):
     .. [1] Louche A, Notton G, Poggi P, Simmonnot G. Correlations for direct normal and global horizontal irradiation on French Mediterranean site. Solar Energy 1991;46:261-6
 
     """
-    bool=np.logical_or(solar_zenith>180,solar_zenith < 0)
-    solar_zenith=np.where(bool,np.NaN,solar_zenith)
+    bool = np.logical_or(solar_zenith > 180, solar_zenith < 0)
+    solar_zenith = np.where(bool, np.NaN, solar_zenith)
 
     if np.isscalar(datetime_or_doy):
-        bool=(np.any(datetime_or_doy>366 or datetime_or_doy < 1,axis=0))
+        bool = (np.any(datetime_or_doy > 366 or datetime_or_doy < 1, axis=0))
         print(bool)
-        datetime_or_doy=np.where(bool,np.NaN,datetime_or_doy)
+        datetime_or_doy = np.where(bool, np.NaN, datetime_or_doy)
 
     # this is the I0 calculation from the reference
     # SSC uses solar constant = 1366.1
@@ -3172,10 +3172,10 @@ def pvl_louche(ghi, solar_zenith, datetime_or_doy):
     dni = kb*I0
     dhi = ghi-dni*tools.cosd(solar_zenith)
 
-    data=OrderedDict()
-    data['dni']=dni
-    data['dhi']=dhi
-    data['kt']=Kt
+    data = OrderedDict()
+    data['dni'] = dni
+    data['dhi'] = dhi
+    data['kt'] = Kt
 
     if isinstance(datetime_or_doy, pd.DatetimeIndex):
         data = pd.DataFrame(data, index=datetime_or_doy)
diff --git a/pvlib/tests/test_irradiance.py b/pvlib/tests/test_irradiance.py
index 0c721cd2eb..8d6b051575 100644
--- a/pvlib/tests/test_irradiance.py
+++ b/pvlib/tests/test_irradiance.py
@@ -1211,12 +1211,12 @@ def test_complete_irradiance():
 
 
 def test_pvl_louche():
-    
+
     index = pd.DatetimeIndex(['20190101']*3 + ['20190620']*3)
     ghi = pd.Series([0, 50, 1000, 1000, 1000, 1000], index=index)
     zenith = pd.Series([120, 85, 10, 10, 182, -2], index=index)
     expected = pd.DataFrame(np.array(
-        [[2.827964,     1.413982,        0.000000],
+        [[2.827964,     1.413982,        -0.000000],
          [130.089669, 38.661938, 0.405724],
          [828.498650, 184.088106, 0.718133],
          [887.407348, 126.074364, 0.768214],
@@ -1226,4 +1226,4 @@ def test_pvl_louche():
 
     out = irradiance.pvl_louche(ghi, zenith, index)
 
-    assert np.allclose(out, expected)
+    assert assert_frame_equal(out, expected) is None

From 66f9c813712433b7ea5f58c06cb9fe13f620121f Mon Sep 17 00:00:00 2001
From: Lakshya Garg <72099449+Lakshyadevelops@users.noreply.github.com>
Date: Tue, 28 Mar 2023 04:10:01 +0530
Subject: [PATCH 05/16] stickler

---
 pvlib/irradiance.py | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/pvlib/irradiance.py b/pvlib/irradiance.py
index b7cc47cfc7..d6df51ac68 100644
--- a/pvlib/irradiance.py
+++ b/pvlib/irradiance.py
@@ -3149,7 +3149,10 @@ def pvl_louche(ghi, solar_zenith, datetime_or_doy):
 
     References
     -------
-    .. [1] Louche A, Notton G, Poggi P, Simmonnot G. Correlations for direct normal and global horizontal irradiation on French Mediterranean site. Solar Energy 1991;46:261-6
+    .. [1] Louche A, Notton G, Poggi P, Simmonnot G. Correlations for direct
+    normal and global horizontal irradiation on French Mediterranean site.
+    Solar Energy
+    1991;46:261-6
 
     """
     bool = np.logical_or(solar_zenith > 180, solar_zenith < 0)

From ff8eb59eb952392eb1915ab6ed842a2f7c3f9240 Mon Sep 17 00:00:00 2001
From: Lakshya Garg <72099449+Lakshyadevelops@users.noreply.github.com>
Date: Sat, 1 Apr 2023 02:14:48 +0530
Subject: [PATCH 06/16] made suggested changes

---
 pvlib/irradiance.py            | 17 +++++++----------
 pvlib/tests/test_irradiance.py |  9 ++++-----
 2 files changed, 11 insertions(+), 15 deletions(-)

diff --git a/pvlib/irradiance.py b/pvlib/irradiance.py
index d6df51ac68..2d0f82e347 100644
--- a/pvlib/irradiance.py
+++ b/pvlib/irradiance.py
@@ -3121,14 +3121,14 @@ def complete_irradiance(solar_zenith,
 
 def pvl_louche(ghi, solar_zenith, datetime_or_doy):
     """
-    Determine DNI and GHI from GHI using louche model.
+    Determine DNI and GHI from GHI using Louche model.
 
     Parameters
     ----------
     ghi : Series
         Global horizontal irradiance. [W/m^2]
 
-    zenith : Series
+    solar_zenith : Series
         True (not refraction-corrected) zenith angles in decimal
         degrees. Angles must be >=0 and <=180.
 
@@ -3151,29 +3151,26 @@ def pvl_louche(ghi, solar_zenith, datetime_or_doy):
     -------
     .. [1] Louche A, Notton G, Poggi P, Simmonnot G. Correlations for direct
     normal and global horizontal irradiation on French Mediterranean site.
-    Solar Energy
-    1991;46:261-6
+    Solar Energy 1991;46:261-6
 
     """
-    bool = np.logical_or(solar_zenith > 180, solar_zenith < 0)
+    bool = np.logical_or(solar_zenith > 90, solar_zenith < 0)
     solar_zenith = np.where(bool, np.NaN, solar_zenith)
 
     if np.isscalar(datetime_or_doy):
         bool = (np.any(datetime_or_doy > 366 or datetime_or_doy < 1, axis=0))
-        print(bool)
         datetime_or_doy = np.where(bool, np.NaN, datetime_or_doy)
 
     # this is the I0 calculation from the reference
     # SSC uses solar constant = 1366.1
     I0 = get_extra_radiation(datetime_or_doy)
 
-    I0h = I0*tools.cosd(solar_zenith)
-    Kt = ghi/I0h
-    pd.Series.clip(Kt, 0, inplace=True)
+    Kt = clearness_index(ghi, solar_zenith, I0)
+
     kb = -10.627*Kt**5 + 15.307*Kt**4 - 5.205 * \
         Kt**3 + 0.994*Kt**2 - 0.059*Kt + 0.002
     dni = kb*I0
-    dhi = ghi-dni*tools.cosd(solar_zenith)
+    dhi = ghi - dni*tools.cosd(solar_zenith)
 
     data = OrderedDict()
     data['dni'] = dni
diff --git a/pvlib/tests/test_irradiance.py b/pvlib/tests/test_irradiance.py
index 8d6b051575..8ecbf03e1b 100644
--- a/pvlib/tests/test_irradiance.py
+++ b/pvlib/tests/test_irradiance.py
@@ -1212,15 +1212,14 @@ def test_complete_irradiance():
 
 def test_pvl_louche():
 
-    index = pd.DatetimeIndex(['20190101']*3 + ['20190620']*3)
-    ghi = pd.Series([0, 50, 1000, 1000, 1000, 1000], index=index)
-    zenith = pd.Series([120, 85, 10, 10, 182, -2], index=index)
+    index = pd.DatetimeIndex(['20190101']*3 + ['20190620']*2)
+    ghi = pd.Series([0, 50, 1000, 1000, 1000], index=index)
+    zenith = pd.Series([91, 85, 10, 10, -2], index=index)
     expected = pd.DataFrame(np.array(
-        [[2.827964,     1.413982,        -0.000000],
+        [[np.NaN, np.NaN, np.NaN],
          [130.089669, 38.661938, 0.405724],
          [828.498650, 184.088106, 0.718133],
          [887.407348, 126.074364, 0.768214],
-         [np.NaN, np.NaN, np.NaN],
          [np.NaN, np.NaN, np.NaN]]),
         columns=['dni', 'dhi', 'kt'], index=index)
 

From 4cbb2bc1e7f909b3d5c91e747f15c99f428373e9 Mon Sep 17 00:00:00 2001
From: Lakshya Garg <72099449+Lakshyadevelops@users.noreply.github.com>
Date: Sat, 1 Apr 2023 03:46:34 +0530
Subject: [PATCH 07/16] updated what's new, doc API changes & added notes

---
 docs/sphinx/source/reference/irradiance/decomposition.rst | 1 +
 docs/sphinx/source/whatsnew/v0.9.6.rst                    | 2 +-
 pvlib/irradiance.py                                       | 4 ++++
 3 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/docs/sphinx/source/reference/irradiance/decomposition.rst b/docs/sphinx/source/reference/irradiance/decomposition.rst
index f0d1495889..90ef0fa3e2 100644
--- a/docs/sphinx/source/reference/irradiance/decomposition.rst
+++ b/docs/sphinx/source/reference/irradiance/decomposition.rst
@@ -15,3 +15,4 @@ DNI estimation models
    irradiance.boland
    irradiance.campbell_norman
    irradiance.gti_dirint
+   irradiance.pvl_louche
diff --git a/docs/sphinx/source/whatsnew/v0.9.6.rst b/docs/sphinx/source/whatsnew/v0.9.6.rst
index 06e7049a28..e8801b9c24 100644
--- a/docs/sphinx/source/whatsnew/v0.9.6.rst
+++ b/docs/sphinx/source/whatsnew/v0.9.6.rst
@@ -11,7 +11,7 @@ Deprecations
 
 Enhancements
 ~~~~~~~~~~~~
-
+* Lakshya Garg (:ghuser:`Lakshyadevelops` :pull:`1705`)
 
 Bug fixes
 ~~~~~~~~~
diff --git a/pvlib/irradiance.py b/pvlib/irradiance.py
index 2d0f82e347..fc0bf2f853 100644
--- a/pvlib/irradiance.py
+++ b/pvlib/irradiance.py
@@ -3146,6 +3146,10 @@ def pvl_louche(ghi, solar_zenith, datetime_or_doy):
               W/m^2.
             * ``kt``: Ratio of global to extraterrestrial irradiance
               on a horizontal plane.
+    Notes
+    -----
+    solar_zenith angles should be between 0 and 90 degrees else NaN will be
+    returned. doy should be between 1 and 366 else NaN will be returned.
 
     References
     -------

From 1562111cc22a1923a8c731c077ffa7e099123cdd Mon Sep 17 00:00:00 2001
From: Lakshya Garg <72099449+Lakshyadevelops@users.noreply.github.com>
Date: Sat, 1 Apr 2023 23:27:03 +0530
Subject: [PATCH 08/16] correct comments

---
 pvlib/irradiance.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pvlib/irradiance.py b/pvlib/irradiance.py
index fc0bf2f853..a89dfa3432 100644
--- a/pvlib/irradiance.py
+++ b/pvlib/irradiance.py
@@ -3130,7 +3130,7 @@ def pvl_louche(ghi, solar_zenith, datetime_or_doy):
 
     solar_zenith : Series
         True (not refraction-corrected) zenith angles in decimal
-        degrees. Angles must be >=0 and <=180.
+        degrees. Angles must be >=0 and <=90.
 
     datetime_or_doy : numeric, pandas.DatetimeIndex
         Day of year or array of days of year e.g.

From 12a52a251508378d6baf8ff6b894a568d6f473cf Mon Sep 17 00:00:00 2001
From: Lakshya Garg <72099449+Lakshyadevelops@users.noreply.github.com>
Date: Mon, 3 Apr 2023 20:36:07 +0530
Subject: [PATCH 09/16] Update pvlib/irradiance.py

Co-authored-by: Cliff Hansen <cwhanse@sandia.gov>
---
 pvlib/irradiance.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/pvlib/irradiance.py b/pvlib/irradiance.py
index a89dfa3432..9e6568d8cd 100644
--- a/pvlib/irradiance.py
+++ b/pvlib/irradiance.py
@@ -3148,8 +3148,8 @@ def pvl_louche(ghi, solar_zenith, datetime_or_doy):
               on a horizontal plane.
     Notes
     -----
-    solar_zenith angles should be between 0 and 90 degrees else NaN will be
-    returned. doy should be between 1 and 366 else NaN will be returned.
+    `solar_zenith` angles should be between 0 and 90 degrees else NaN will be
+    returned. Day of year (doy) should be between 1 and 366 else NaN will be returned.
 
     References
     -------

From c111d69ad32c76ef3653a1db8af6a818cdbc1ce3 Mon Sep 17 00:00:00 2001
From: Lakshya Garg <72099449+Lakshyadevelops@users.noreply.github.com>
Date: Mon, 3 Apr 2023 20:42:30 +0530
Subject: [PATCH 10/16] complete PR with formatting changes

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

diff --git a/pvlib/irradiance.py b/pvlib/irradiance.py
index 9e6568d8cd..3ae1c67b52 100644
--- a/pvlib/irradiance.py
+++ b/pvlib/irradiance.py
@@ -3154,8 +3154,8 @@ def pvl_louche(ghi, solar_zenith, datetime_or_doy):
     References
     -------
     .. [1] Louche A, Notton G, Poggi P, Simmonnot G. Correlations for direct
-    normal and global horizontal irradiation on French Mediterranean site.
-    Solar Energy 1991;46:261-6
+       normal and global horizontal irradiation on French Mediterranean site.
+       Solar Energy 1991;46:261-6
 
     """
     bool = np.logical_or(solar_zenith > 90, solar_zenith < 0)

From 65d27ce003a6101a72b4c694880c626898eb755f Mon Sep 17 00:00:00 2001
From: Lakshya Garg <72099449+Lakshyadevelops@users.noreply.github.com>
Date: Mon, 3 Apr 2023 20:54:35 +0530
Subject: [PATCH 11/16] stickler

---
 pvlib/irradiance.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/pvlib/irradiance.py b/pvlib/irradiance.py
index 3ae1c67b52..9c45928b00 100644
--- a/pvlib/irradiance.py
+++ b/pvlib/irradiance.py
@@ -3149,7 +3149,8 @@ def pvl_louche(ghi, solar_zenith, datetime_or_doy):
     Notes
     -----
     `solar_zenith` angles should be between 0 and 90 degrees else NaN will be
-    returned. Day of year (doy) should be between 1 and 366 else NaN will be returned.
+    returned. Day of year (doy) should be between 1 and 366 else NaN will be
+    returned.
 
     References
     -------

From c14c735b9beccd9527f7cd93cad21552da00137c Mon Sep 17 00:00:00 2001
From: Lakshya Garg <72099449+Lakshyadevelops@users.noreply.github.com>
Date: Sat, 27 May 2023 23:26:00 +0530
Subject: [PATCH 12/16] Update pvlib/irradiance.py

Co-authored-by: Kevin Anderson <kevin.anderso@gmail.com>
---
 pvlib/irradiance.py | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/pvlib/irradiance.py b/pvlib/irradiance.py
index 9c45928b00..0f207a87eb 100644
--- a/pvlib/irradiance.py
+++ b/pvlib/irradiance.py
@@ -3154,9 +3154,9 @@ def pvl_louche(ghi, solar_zenith, datetime_or_doy):
 
     References
     -------
-    .. [1] Louche A, Notton G, Poggi P, Simmonnot G. Correlations for direct
-       normal and global horizontal irradiation on French Mediterranean site.
-       Solar Energy 1991;46:261-6
+    .. [1] Louche A, Notton G, Poggi P, Simonnot G. Correlations for direct
+       normal and global horizontal irradiation on a French Mediterranean site.
+       Solar Energy 1991;46:261-6. :doi:`10.1016/0038-092X(91)90072-5`
 
     """
     bool = np.logical_or(solar_zenith > 90, solar_zenith < 0)

From 1bcdd19baa7d89ac581a9ada4e3e94d0a1dda28d Mon Sep 17 00:00:00 2001
From: Lakshya Garg <72099449+Lakshyadevelops@users.noreply.github.com>
Date: Sun, 28 May 2023 00:25:12 +0530
Subject: [PATCH 13/16] done necessary changes

---
 docs/sphinx/source/whatsnew/v0.9.6.rst |  3 ++-
 pvlib/irradiance.py                    | 17 ++++++++---------
 pvlib/tests/test_irradiance.py         | 15 +++++++--------
 3 files changed, 17 insertions(+), 18 deletions(-)

diff --git a/docs/sphinx/source/whatsnew/v0.9.6.rst b/docs/sphinx/source/whatsnew/v0.9.6.rst
index e8801b9c24..9178e38045 100644
--- a/docs/sphinx/source/whatsnew/v0.9.6.rst
+++ b/docs/sphinx/source/whatsnew/v0.9.6.rst
@@ -11,7 +11,7 @@ Deprecations
 
 Enhancements
 ~~~~~~~~~~~~
-* Lakshya Garg (:ghuser:`Lakshyadevelops` :pull:`1705`)
+* Added a new irradiance decomposition model :py:func:`pvlib.irradiance.louche`. (:pull:`1705`)
 
 Bug fixes
 ~~~~~~~~~
@@ -35,4 +35,5 @@ Requirements
 
 Contributors
 ~~~~~~~~~~~~
+* Lakshya Garg (:ghuser:`Lakshyadevelops` :pull:`1705`)
 
diff --git a/pvlib/irradiance.py b/pvlib/irradiance.py
index 0f207a87eb..c984a469f2 100644
--- a/pvlib/irradiance.py
+++ b/pvlib/irradiance.py
@@ -3119,16 +3119,16 @@ def complete_irradiance(solar_zenith,
     return component_sum_df
 
 
-def pvl_louche(ghi, solar_zenith, datetime_or_doy):
+def louche(ghi, solar_zenith, datetime_or_doy, max_zenith=90):
     """
     Determine DNI and GHI from GHI using Louche model.
 
     Parameters
     ----------
-    ghi : Series
+    ghi : numeric
         Global horizontal irradiance. [W/m^2]
 
-    solar_zenith : Series
+    solar_zenith : numeric
         True (not refraction-corrected) zenith angles in decimal
         degrees. Angles must be >=0 and <=90.
 
@@ -3159,12 +3159,6 @@ def pvl_louche(ghi, solar_zenith, datetime_or_doy):
        Solar Energy 1991;46:261-6. :doi:`10.1016/0038-092X(91)90072-5`
 
     """
-    bool = np.logical_or(solar_zenith > 90, solar_zenith < 0)
-    solar_zenith = np.where(bool, np.NaN, solar_zenith)
-
-    if np.isscalar(datetime_or_doy):
-        bool = (np.any(datetime_or_doy > 366 or datetime_or_doy < 1, axis=0))
-        datetime_or_doy = np.where(bool, np.NaN, datetime_or_doy)
 
     # this is the I0 calculation from the reference
     # SSC uses solar constant = 1366.1
@@ -3177,6 +3171,11 @@ def pvl_louche(ghi, solar_zenith, datetime_or_doy):
     dni = kb*I0
     dhi = ghi - dni*tools.cosd(solar_zenith)
 
+    bad_values = (solar_zenith > max_zenith) | (ghi < 0) | (dni < 0)
+    dni = np.where(bad_values, 0, dni)
+    # ensure that closure relationship remains valid
+    dhi = np.where(bad_values, ghi, dhi)
+
     data = OrderedDict()
     data['dni'] = dni
     data['dhi'] = dhi
diff --git a/pvlib/tests/test_irradiance.py b/pvlib/tests/test_irradiance.py
index 8ecbf03e1b..1755ac06b1 100644
--- a/pvlib/tests/test_irradiance.py
+++ b/pvlib/tests/test_irradiance.py
@@ -1210,19 +1210,18 @@ def test_complete_irradiance():
                                        dni_clear=clearsky.dni)
 
 
-def test_pvl_louche():
+def test_louche():
 
-    index = pd.DatetimeIndex(['20190101']*3 + ['20190620']*2)
-    ghi = pd.Series([0, 50, 1000, 1000, 1000], index=index)
-    zenith = pd.Series([91, 85, 10, 10, -2], index=index)
+    index = pd.DatetimeIndex(['20190101']*3 + ['20190620']*1)
+    ghi = pd.Series([0, 50, 1000, 1000], index=index)
+    zenith = pd.Series([91, 85, 10, 10], index=index)
     expected = pd.DataFrame(np.array(
-        [[np.NaN, np.NaN, np.NaN],
+        [[0, 0, 0],
          [130.089669, 38.661938, 0.405724],
          [828.498650, 184.088106, 0.718133],
-         [887.407348, 126.074364, 0.768214],
-         [np.NaN, np.NaN, np.NaN]]),
+         [887.407348, 126.074364, 0.768214]]),
         columns=['dni', 'dhi', 'kt'], index=index)
 
-    out = irradiance.pvl_louche(ghi, zenith, index)
+    out = irradiance.louche(ghi, zenith, index)
 
     assert assert_frame_equal(out, expected) is None

From bf61e972a51ed2d3132875c3b139aa2e208cd6db Mon Sep 17 00:00:00 2001
From: Lakshya Garg <72099449+Lakshyadevelops@users.noreply.github.com>
Date: Tue, 30 May 2023 16:04:17 +0530
Subject: [PATCH 14/16] Update
 docs/sphinx/source/reference/irradiance/decomposition.rst

Co-authored-by: Cliff Hansen <cwhanse@sandia.gov>
---
 docs/sphinx/source/reference/irradiance/decomposition.rst | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/docs/sphinx/source/reference/irradiance/decomposition.rst b/docs/sphinx/source/reference/irradiance/decomposition.rst
index 90ef0fa3e2..0677d6ac95 100644
--- a/docs/sphinx/source/reference/irradiance/decomposition.rst
+++ b/docs/sphinx/source/reference/irradiance/decomposition.rst
@@ -15,4 +15,5 @@ DNI estimation models
    irradiance.boland
    irradiance.campbell_norman
    irradiance.gti_dirint
-   irradiance.pvl_louche
+   irradiance.louche
+

From 3abbc7933cead78bdc8c349ed6ab9fa73a1ed6fd Mon Sep 17 00:00:00 2001
From: Lakshya Garg <72099449+Lakshyadevelops@users.noreply.github.com>
Date: Tue, 30 May 2023 16:08:36 +0530
Subject: [PATCH 15/16] removed SSC comment

---
 pvlib/irradiance.py | 2 --
 1 file changed, 2 deletions(-)

diff --git a/pvlib/irradiance.py b/pvlib/irradiance.py
index c984a469f2..f457d1fa7d 100644
--- a/pvlib/irradiance.py
+++ b/pvlib/irradiance.py
@@ -3160,8 +3160,6 @@ def louche(ghi, solar_zenith, datetime_or_doy, max_zenith=90):
 
     """
 
-    # this is the I0 calculation from the reference
-    # SSC uses solar constant = 1366.1
     I0 = get_extra_radiation(datetime_or_doy)
 
     Kt = clearness_index(ghi, solar_zenith, I0)

From 57b6af096e1a227b81ec42445491f6493f1966c8 Mon Sep 17 00:00:00 2001
From: Kevin Anderson <kevin.anderso@gmail.com>
Date: Tue, 30 May 2023 09:27:30 -0400
Subject: [PATCH 16/16] Apply suggestions from code review

---
 pvlib/irradiance.py            | 7 +------
 pvlib/tests/test_irradiance.py | 2 +-
 2 files changed, 2 insertions(+), 7 deletions(-)

diff --git a/pvlib/irradiance.py b/pvlib/irradiance.py
index f457d1fa7d..af983e47b9 100644
--- a/pvlib/irradiance.py
+++ b/pvlib/irradiance.py
@@ -3121,7 +3121,7 @@ def complete_irradiance(solar_zenith,
 
 def louche(ghi, solar_zenith, datetime_or_doy, max_zenith=90):
     """
-    Determine DNI and GHI from GHI using Louche model.
+    Determine DNI and DHI from GHI using the Louche model.
 
     Parameters
     ----------
@@ -3146,11 +3146,6 @@ def louche(ghi, solar_zenith, datetime_or_doy, max_zenith=90):
               W/m^2.
             * ``kt``: Ratio of global to extraterrestrial irradiance
               on a horizontal plane.
-    Notes
-    -----
-    `solar_zenith` angles should be between 0 and 90 degrees else NaN will be
-    returned. Day of year (doy) should be between 1 and 366 else NaN will be
-    returned.
 
     References
     -------
diff --git a/pvlib/tests/test_irradiance.py b/pvlib/tests/test_irradiance.py
index 1755ac06b1..d0158dad1a 100644
--- a/pvlib/tests/test_irradiance.py
+++ b/pvlib/tests/test_irradiance.py
@@ -1224,4 +1224,4 @@ def test_louche():
 
     out = irradiance.louche(ghi, zenith, index)
 
-    assert assert_frame_equal(out, expected) is None
+    assert_frame_equal(out, expected)