If BIPV is proposed for Southern walls, then will it be treated as transparent or opaque for WWR calculation?

There is no absolute categorization for BIPV as opaque or transparent material. It’s dependent on the way it has been installed and the material specification submitted by the product manufacturers. For example, if it is being used as a window pane or glazing, then it will be included in WWR calculation. But, if it is installed as shading device, then it will not be included in WWR calculation. Please check the details with the manufacturers. A project specific discussion with GRIHA Council is recommended in unique cases to ensure proper course of action.