Clean up and add Github features (#9)

* .gitattributes language override to make sure repo is Python

* Add build status badge to readme file

* Clean up horizon band shading commenting

* Adding documentation in gitattributes

.gitattributes

@@ -1 +1,8 @@
 pvfactors/_version.py export-subst
+
+# mark iPython notebooks as Python files
+*.ipynb linguist-language=Python
+
+# documentation
+pvfactors/docs/* linguist-documentation
+notebooks/* linguist-documentation

README.md

@@ -1,6 +1,8 @@
 pvfactors (open-source fork of vf_model)
 ========================================
 
+[![CircleCI](https://circleci.com/gh/SunPower/pvfactors.svg?style=svg)](https://circleci.com/gh/SunPower/pvfactors)
+
 pvfactors is a tool designed for PV professionals to calculate the
 irradiance incident on surfaces of a photovoltaic array. It relies on the use of
 2D geometries and view factors integrated mathematically into a linear system of

pvfactors/pvarray.py

@@ -347,32 +347,13 @@ def update_irradiance_terms_perez(self, solar_zenith, solar_azimuth,
         # TODO: poa_horizon should not be negative... but it can be in the Perez
         # model from pvlib
         poa_horizon = np.abs(poa_horizon)
-        # FIXME: poa_horizon should be different in front and back: this is
-        # what the code below was doing
-        # if self.pvrows[0].facing == 'left':
-        #     self.surface_registry.loc[
-        #         (self.surface_registry.pvrow_index == 0)
-        #         & (self.surface_registry.surface_side == 'front'),
-        #         'irradiance_term'] += poa_horizon
-        #     self.surface_registry.loc[
-        #         (self.surface_registry.pvrow_index == self.n_pvrows - 1)
-        #         & (self.surface_registry.surface_side == 'back'),
-        #         'irradiance_term'] += poa_horizon
-        # elif self.pvrows[0].facing == 'right':
-        #     self.surface_registry.loc[
-        #         (self.surface_registry.pvrow_index == self.n_pvrows - 1)
-        #         & (self.surface_registry.surface_side == 'front'),
-        #         'irradiance_term'] += poa_horizon
-        #     self.surface_registry.loc[
-        #         (self.surface_registry.pvrow_index == 0)
-        #         & (self.surface_registry.surface_side == 'back'),
-        #         'irradiance_term'] += poa_horizon
-
-        # TODO: test if should have poa_horizon on all pvrows at all times
+
+        # Add poa horizon contribution to all pvrow surfaces
         self.surface_registry.loc[
             (self.surface_registry.line_type == 'pvrow'),
             'horizon_term'] += poa_horizon
 
+        # Apply horizon band shading for the pvrow back surfaces
         self.apply_horizon_band_shading('back')
 
         if aoi_frontsurface <= 90.: