use _lambertw_pvlib etc. by cwhanse · Pull Request #2732

use _lambertw_pvlib etc. by cwhanse · Pull Request #2732 · pvlib/pvlib-python

Seems like this warning is commonly (always?) emitted now:

pvlib-python\pvlib\ivtools\utils.py:563: RuntimeWarning: invalid value encountered in subtract
  w = logx - np.log(logx)  # initial guess, w = log(x) - log(log(x))

Here's a reproducer:

import pvlib
cec = pvlib.pvsystem.retrieve_sam('cecmod')
sdm_params = cec['Canadian_Solar_Inc__CS1U_400MS']
sdm_params = sdm_params[['alpha_sc', 'a_ref', 'I_L_ref', 'I_o_ref', 'R_sh_ref', 'R_s', 'Adjust']]
sde_params = pvlib.pvsystem.calcparams_cec(1000, 25, **sdm_params)
iv = pvlib.pvsystem.singlediode(*sde_params)