use _lambertw_pvlib in ivtools

Author: cwhanse

pvlib/ivtools/sdm/_fit_desoto_pvsyst_sandia.py

@@ -5,10 +5,9 @@
 import numpy as np
 
 from scipy import optimize
-from scipy.special import lambertw
 
 from pvlib.pvsystem import singlediode, v_from_i
-from pvlib.ivtools.utils import rectify_iv_curve, _numdiff
+from pvlib.ivtools.utils import rectify_iv_curve, _numdiff, _lambertw_pvlib
 from pvlib.pvsystem import _pvsyst_Rsh
 
 
@@ -535,7 +534,7 @@ def _calc_theta_phi_exact(vmp, imp, iph, io, rs, rsh, nnsvth):
             nnsvth == 0,
             np.nan,
             rsh * io / nnsvth * np.exp(rsh * (iph + io - imp) / nnsvth))
-        phi = np.where(argw > 0, lambertw(argw).real, np.nan)
+        phi = np.where(argw > 0, _lambertw_pvlib(argw), np.nan)
 
     # NaN where argw overflows. Switch to log space to evaluate
     u = np.isinf(argw)
@@ -561,7 +560,7 @@ def _calc_theta_phi_exact(vmp, imp, iph, io, rs, rsh, nnsvth):
             np.nan,
             rsh / (rsh + rs) * rs * io / nnsvth * np.exp(
                 rsh / (rsh + rs) * (rs * (iph + io) + vmp) / nnsvth))
-        theta = np.where(argw > 0, lambertw(argw).real, np.nan)
+        theta = np.where(argw > 0, _lambertw_pvlib(argw), np.nan)
 
     # NaN where argw overflows. Switch to log space to evaluate
     u = np.isinf(argw)

pvlib/ivtools/sdm/desoto.py

@@ -2,9 +2,8 @@
 
 from scipy import constants
 from scipy import optimize
-from scipy.special import lambertw
 
-from pvlib.ivtools.utils import rectify_iv_curve
+from pvlib.ivtools.utils import rectify_iv_curve, _lambertw_pvlib
 from pvlib.ivtools.sde import _fit_sandia_cocontent
 
 from pvlib.ivtools.sdm._fit_desoto_pvsyst_sandia import (
@@ -454,7 +453,7 @@ def fit_desoto_batzelis(v_mp, i_mp, v_oc, i_sc, alpha_sc, beta_voc):
     # Equation numbers refer to [1]
     t0 = 298.15  # K
     del0 = (1 - beta_voc * t0) / (50.1 - alpha_sc * t0)  # Eq 9
-    w0 = np.real(lambertw(np.exp(1/del0 + 1)))
+    w0 = _lambertw_pvlib(np.exp(1/del0 + 1))
 
     # Eqs 11-15
     a0 = del0 * v_oc