Living in Spain, I don’t have mosque following ahl al bayt here. Is it better for me to pray salat jumaa with our sunni brothers (but so it will be on the carpet) or to do it alone at home? Otherwise is there any other solutions ?

It is better to pray with them, reciting Alhamd and the surah and try to put something for sojood, like a piece of paper, and if it is not possible, you can pray on the carpet.