Create ivtools

ci/requirements-py35.yml

@@ -24,4 +24,5 @@ dependencies:
     - shapely  # pvfactors dependency
     - siphon  # conda-forge
     - pip:
+        - nrel-pysam
         - pvfactors==1.0.1

ci/requirements-py36.yml

@@ -24,4 +24,5 @@ dependencies:
     - shapely  # pvfactors dependency
     - siphon  # conda-forge
     - pip:
+        - nrel-pysam
         - pvfactors==1.0.1

ci/requirements-py37.yml

@@ -24,4 +24,5 @@ dependencies:
     - shapely  # pvfactors dependency
     - siphon  # conda-forge
     - pip:
+        - nrel-pysam
         - pvfactors==1.0.1

docs/sphinx/source/api.rst

@@ -294,6 +294,14 @@ PVWatts model
    pvsystem.pvwatts_losses
    pvsystem.pvwatts_losses
 
+Functions for fitting PV models
+-------------------------------
+.. autosummary::
+   :toctree: generated/
+
+    ivtools.fit_sde_sandia
+    ivtools.fit_sdm_cec_sam
+
 Other
 -----
 

docs/sphinx/source/whatsnew/v0.7.0.rst

@@ -104,6 +104,26 @@ Documentation
 ~~~~~~~~~~~~~
 * Corrected docstring for `pvsystem.PVSystem.sapm`
 
+API Changes
+~~~~~~~~~~~
+
+
+Enhancements
+~~~~~~~~~~~~
+* Add `ivtools` module to contain functions for IV model fitting.
+* Add :py:func:`~pvlib.ivtools.fit_sde_sandia`, a simple method to fit
+  the single diode equation to an IV curve.
+* Add :py:func:`~pvlib.ivtools.fit_sdm_cec_sam`, a wrapper for the CEC single
+  diode model fitting function '6parsolve' from NREL's System Advisor Model.
+
+
+Bug fixes
+~~~~~~~~~
+
+
+Testing
+~~~~~~~
+
 Removal of prior version deprecations
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 * Removed `irradiance.extraradiation`.
@@ -119,6 +139,7 @@ Contributors
 ~~~~~~~~~~~~
 * Mark Campanellli (:ghuser:`markcampanelli`)
 * Will Holmgren (:ghuser:`wholmgren`)
+* Cliff Hansen (:ghuser:`cwhanse`)
 * Oscar Dowson (:ghuser:`odow`)
 * Anton Driesse (:ghuser:`adriesse`)
 * Alexander Morgan (:ghuser:`alexandermorgan`)

pvlib/__init__.py

@@ -7,6 +7,7 @@
 from pvlib import location
 from pvlib import solarposition
 from pvlib import iotools
+from pvlib import ivtools
 from pvlib import tracking
 from pvlib import pvsystem
 from pvlib import spa