Add PVSPEC spectral correction factor model

pvlib/tests/test_pelland.py

@@ -0,0 +1,74 @@
+import numpy as np
+from warnings import warn
+
+def spectral_factor_pelland(airmass_absolute, clearness_index,
+                            module_type = None, coefficients = None,
+                            min_airmass_absolute = 0.58,
+                            max_airmass_absolute = 10):
+    #0.58 -> same as spectral_factor_firstsolar
+# =============================================================================
+#     model implemented: https://ieeexplore.ieee.org/document/9300932
+#     inputs: air mass, clearness index
+#     coefficients: six modules
+# =============================================================================
+# =============================================================================
+#      --- Screen Input Data ---
+# =============================================================================
+    #kc
+    kc = np.atleast_1d(clearness_index)
+    kc = kc.astype('float64')
+    if np.min(kc) < 0:
+        raise ValueError('Clearness index cannot be less than 0')
+    if np.max(kc) > 1:
+        raise ValueError('Clearness index cannot be grater than 1')
+    #ama
+    if np.max(airmass_absolute) > max_airmass_absolute:
+        warn('High air mass values greater than 'f'{max_airmass_absolute} '+
+             'in dataset')
+    # Warn user about exceptionally low ama data
+    if np.min(airmass_absolute) < min_airmass_absolute:
+        airmass_absolute = np.maximum(airmass_absolute, min_airmass_absolute )
+        warn('Exceptionally low air mass: ' +
+             'model not intended for extra-terrestrial use')
+# =============================================================================
+#      --- Default coefficients ---
+# =============================================================================
+    _coefficients = {}
+    _coefficients['polysi'] = (
+        0.9847, -0.05237, 0.03034)
+    _coefficients['monosi'] = (
+        0.9845, -0.05169, 0.03034)
+    _coefficients['fs-2'] = (
+        1.002, -0.07108, 0.02465)
+    _coefficients['fs-4'] = (
+        0.9981, -0.05776, 0.02336)
+    _coefficients['cigs'] = (
+        0.9791, -0.03904, 0.03096)
+    _coefficients['asi'] = (
+        1.051, -0.1033, 0.009838)
+    _coefficients['multisi'] = _coefficients['polysi']
+    _coefficients['xsi'] = _coefficients['monosi']
+# =============================================================================
+#      --- Check arguments ---
+# =============================================================================
+    if module_type is not None and coefficients is None:
+        coefficients = _coefficients[module_type.lower()]
+    elif module_type is None and coefficients is not None:
+        pass
+    elif module_type is None and coefficients is None:
+        raise TypeError('No valid input provided, both module_type and ' +
+                        'coefficients are None. module_type can be one of ' +
+                        'poly-Si, monosi, fs-2, fs-4, cigs, or asi')
+    else:
+        raise TypeError('Cannot resolve input, must supply only one of ' +
+                        'module_type and coefficients. module_type can be ' +
+                        'one of poly-Si, monosi, fs-2, fs-4, cigs, or asi')
+# =============================================================================
+#      --- Specral mismatch calculation ---
+# =============================================================================
+    coeff = coefficients
+    ama = airmass_absolute
+    kc = clearness_index
+    modifier = coeff[0]*kc**(coeff[1])*ama**(coeff[2])
+
+    return modifier