Documentation improvement

[birgits]

I just stumbled across two things in the documentation where it would be helpful to correct them:

• For the surface_tilt in the PVSystem class it says:

Up=0, horizon=90.

This is a bit confusing since I guess it is meant as defined in the basic_chain:

The tilt angle is defined as degrees from horizontal (e.g. surface facing up = 0, surface facing horizon = 90)

Is that right? Maybe we could use the same definition in the PVSystem class.

• In the docstring of the Modelchain class the default value for the orientation_strategy south_at_latitude_tilt is missing.

[wholmgren]

Is that right?

That is right. It could be updated in a lot of places. Many other parameters could be made more consistent.

In the docstring of the Modelchain class the default value for the orientation_strategy south_at_latitude_tilt is missing.

We generally have not put default values in the doc strings. I think they're useful, though, so feel free to add this. I'd only ask that we add defaults to all parameters of a function, instead of only a single parameter. See also #290.

[uvchik]

According to #290 we may want to add a comment to the docstring entry of orientation_strategy:

(default: 'south_at_latitude_tilt') WARNING: The default will be set to None from version 0.5.x on.

def __init__(self, system, location,
-            orientation_strategy='south_at_latitude_tilt',
+            orientation_strategy='old_default`,
             clearsky_model='ineichen',
             ....

+     if orientation_strategy == 'old_default'
+        orientation_strategy='south_at_latitude_tilt'
+        warnings.warn("Default value will be changed.... ", FutureWarning)

People can switch of this warning by defining the parameter explicitly and so they ready for the changes.

[wholmgren]

closed by #336