There is no difference in the feathering process between the Solar and other observations, except for the case that the field of view is very near the solar limb (< the diameter of the primary beam). For the limb observations, you might need to apply the primary beam deconvolution to the Total Power (TP) data. However, this depends on the overall science goals of the observing program.

For more information and a guide to feathering Solar data taken with ALMA, refer to the Sunspot_Band6_Feathering CASA Guide available at here.