ENH: add methods and tests for a explicit IV curve calculation of single-diode model

.gitignore

@@ -1,4 +1,5 @@
 # Byte-compiled / optimized / DLL files
+.pytest_cache/
 __pycache__/
 *.py[cod]
 

docs/sphinx/source/api.rst

@@ -65,7 +65,6 @@ algorithm.
 
    spa
 
-
 Correlations and analytical expressions for low precision solar position
 calculations.
 
@@ -80,6 +79,7 @@ calculations.
    solarposition.equation_of_time_pvcdrom
    solarposition.hour_angle
 
+
 Clear sky
 =========
 
@@ -206,6 +206,18 @@ Functions relevant for the single diode model.
    pvsystem.i_from_v
    pvsystem.singlediode
    pvsystem.v_from_i
+   pvsystem.max_power_point
+
+Low-level functions for solving the single diode equation.
+
+.. autosummary::
+   :toctree: generated/
+
+   singlediode_methods.estimate_voc
+   singlediode_methods.bishop88
+   singlediode_methods.bishop88_i_from_v
+   singlediode_methods.bishop88_v_from_i
+   singlediode_methods.bishop88_mpp
 
 SAPM model
 ----------
@@ -232,7 +244,6 @@ PVWatts model
    pvsystem.pvwatts_ac
    pvsystem.pvwatts_losses
 
-
 Other
 -----
 

docs/sphinx/source/whatsnew/v0.6.0.rst

@@ -11,10 +11,43 @@ API Changes
 
 Enhancements
 ~~~~~~~~~~~~
-* Add sea surface albedo in irradiance.py (:issue:`458`)
-* Implement first_solar_spectral_loss in modelchain.py (:issue:`359`)
-* Clarify arguments Egref and dEgdT for calcparams_desoto (:issue:`462`)
-* Add pvsystem.calcparams_pvsyst to compute values for the single diode equation using the PVsyst v6 model (:issue:'470')
+* Add sea surface albedo in ``irradiance.py`` (:issue:`458`)
+* Implement :meth:`~pvlib.modelchain.ModelChain.first_solar_spectral_loss`
+  in ``modelchain.py`` (:issue:`359`)
+* Clarify arguments ``Egref`` and ``dEgdT`` for
+  :func:`~pvlib.pvsystem.calcparams_desoto` (:issue:`462`)
+* Add pvsystem.calcparams_pvsyst to compute values for the single diode equation
+  using the PVsyst v6 model (:issue:'470')
+* Extend :func:`~pvlib.pvsystem.singlediode` with an additional keyword argument
+  ``method`` in ``('lambertw', 'newton', 'brentq')``, default is ``'lambertw'``,
+  to select a method to solve the single diode equation for points on the IV
+  curve. Selecting either ``'brentq'`` or ``'newton'`` as the method uses
+  :func:`~pvlib.singlediode_methods.bishop88` with the corresponding method.
+  (:issue:`410`)
+* Implement new methods ``'brentq'`` and ``'newton'`` for solving the single
+  diode equation for points on the IV curve. ``'brentq'`` uses a bisection
+  method (Brent, 1973) that may be slow but guarantees a solution. ``'newton'``
+  uses the Newton-Raphson method and may be faster but is not guaranteed to
+  converge. However, ``'newton'`` should be safe for well-behaved IV curves.
+  (:issue:`408`)
+* Implement :func:`~pvlib.singlediode_methods.bishop88` for explicit calculation
+  of arbitrary IV curve points using diode voltage instead of cell voltage. If
+  ``method`` is either ``'newton'`` or ``'brentq'`` and ``ivcurve_pnts`` in
+  :func:`~pvlib.pvsystem.singlediode` is provided, the IV curve points will be
+  log spaced instead of linear.
+* Implement :func:`~pvlib.singlediode_methods.estimate_voc` to estimate open
+  circuit voltage by assuming :math:`R_{sh} \to \infty` and :math:`R_s=0` as an
+  upper bound in bisection method for :func:`~pvlib.pvsystem.singlediode` when
+  method is either ``'newton'`` or ``'brentq'``.
+* Add :func:`~pvlib.pvsystem.max_power_point` method to compute the max power
+  point using the new ``'brentq'`` method.
+* Add new module ``pvlib.singlediode_methods`` with low-level functions for
+  solving the single diode equation such as:
+  :func:`~pvlib.singlediode_methods.bishop88`,
+  :func:`~pvlib.singlediode_methods.estimate_voc`,
+  :func:`~pvlib.singlediode_methods.bishop88_i_from_v`,
+  :func:`~pvlib.singlediode_methods.bishop88_v_from_i`, and
+  :func:`~pvlib.singlediode_methods.bishop88_mpp`.
 
 
 Bug fixes
@@ -50,5 +83,6 @@ Contributors
 * Will Holmgren
 * Yu Cao
 * Cliff Hansen
+* Mark Mikofski
 * Alan Mathew
 

pvlib/__init__.py

@@ -11,3 +11,4 @@
 from pvlib import pvsystem
 from pvlib import spa
 from pvlib import modelchain
+from pvlib import singlediode_methods