How can I sort by a column while binning another

I am trying to cut float values of each country while grouping them by continent.This is the code that I wrote out:

groups = renew.groupby(['Continent'],pd.cut(renew['% Renewable'], 5))

Bug I am getting this error

TypeError: can only concatenate str (not "float") to str

I don't understand where it is trying to concatenate but I am trying to seperate the values in the '% Renewable' column into 5 bins.