Wrong Return in documentation of cloud_covr_to_transmittance_linear

[JoLo90]

In the documentation of the pvlib.forecast.NDFD.cloud_cover_to_transmittance_linear function, it seems the documented return is the wrong one: It shows the GHI as the return instead of the transmittance.

Here is the function in pvlib.forecast that seems to confirm the case.

    """
    Convert cloud cover to atmospheric transmittance using a linear
    model.

    0% cloud cover returns offset.

    100% cloud cover returns 0.

    Parameters
    ----------
    cloud_cover : numeric
        Cloud cover in %.
    offset : numeric, default 0.75
        Determines the maximum transmittance.
    kwargs
        Not used.

    Returns
    -------
    ghi : numeric
        Estimated GHI.
    """
    transmittance = ((100.0 - cloud_cover) / 100.0) * offset

    return transmittance`

[AdamRJensen]

Seems like it was a mistake when the function was added in #180.

Should probably be updated to something like this:

Returns
-------
transmittance: numeric
    Estimated transmittance.

Perhaps it's worth denoting that it is a fraction and not in percentage like the cloud cover?

[cwhanse]

it's worth denoting that it is a fraction

Absolutely

[AdamRJensen]

@JoLo90 If you wanted to make a pull request for this issue, that would be more than welcomed.

[JoLo90]

@AdamRJensen I'll create a PR in the next days.

[kandersolar]

Closed by #1370, thanks @JoLo90!