Fix crash in ModelChain.infer_spectral_model due to incorrect method call (2) (#629)

* Fix incorrect call to pvsystem instead of self.system

* Update whatsnew

* Add a test for infer_spectral_model

* Add name to whatsnew

* Revert change in comment

Author: Jonathan Gaffiot

docs/sphinx/source/whatsnew/v0.6.1.rst

@@ -55,6 +55,7 @@ Bug fixes
   and < 1900, fix year 2050 which was returning 0.
 * Fix and improve :func:`~pvlib.solarposition.hour_angle` (:issue:`598`)
 * Fix error in :func:`pvlib.clearsky.detect_clearsky` (:issue:`506`)
+* Fix error in :func:`pvlib.modelchain.ModelChain.infer_spectral_model` (:issue:`619`)
 
 
 Testing
@@ -72,3 +73,4 @@ Contributors
 * Cliff Hansen (:ghuser:`cwhanse`)
 * Mark Mikofski (:ghuser:`mikofski`)
 * Anton Driesse (:ghuser:`adriesse`)
+* Jonathan Gaffiot (:ghuser:`jgaffiot`)

pvlib/modelchain.py

@@ -622,7 +622,7 @@ def infer_spectral_model(self):
             return self.sapm_spectral_loss
         elif ((('Technology' in params or
                 'Material' in params) and
-               (pvsystem._infer_cell_type() is not None)) or
+               (self.system._infer_cell_type() is not None)) or
               'first_solar_spectral_coefficients' in params):
             return self.first_solar_spectral_loss
         else:

pvlib/test/test_modelchain.py

@@ -54,6 +54,19 @@ def cec_dc_snl_ac_system(sam_data):
     return system
 
 
+@pytest.fixture
+def cec_dc_native_snl_ac_system(sam_data):
+    module = 'Canadian_Solar_CS5P_220M'
+    module_parameters = sam_data['cecmod'][module].copy()
+    inverters = sam_data['cecinverter']
+    inverter = inverters['ABB__MICRO_0_25_I_OUTD_US_208_208V__CEC_2014_'].copy()
+    system = PVSystem(surface_tilt=32.2, surface_azimuth=180,
+                      module=module,
+                      module_parameters=module_parameters,
+                      inverter_parameters=inverter)
+    return system
+
+
 @pytest.fixture
 def pvsyst_dc_snl_ac_system(sam_data, pvsyst_module_params):
     module = 'PVsyst test module'
@@ -251,6 +264,21 @@ def test_infer_dc_model(system, cec_dc_snl_ac_system, pvsyst_dc_snl_ac_system,
     assert isinstance(mc.dc, (pd.Series, pd.DataFrame))
 
 
+@pytest.mark.parametrize('dc_model', [
+    'sapm',
+    pytest.param('cec', marks=requires_scipy),
+    pytest.param('cec_native', marks=requires_scipy)])
+def test_infer_spectral_model(location, system, cec_dc_snl_ac_system,
+                              cec_dc_native_snl_ac_system, dc_model):
+    dc_systems = {'sapm': system,
+                  'cec': cec_dc_snl_ac_system,
+                  'cec_native': cec_dc_native_snl_ac_system}
+    system = dc_systems[dc_model]
+    mc = ModelChain(system, location,
+                    orientation_strategy='None', aoi_model='physical')
+    assert isinstance(mc, ModelChain)
+
+
 def test_dc_model_user_func(pvwatts_dc_pvwatts_ac_system, location, weather,
                             mocker):
     m = mocker.spy(sys.modules[__name__], 'poadc')