In some flats where balcony solar isn't allowed because the landlord is a bastard, people have been building solar tables, which is just a panel with four legs. There is no rule against having a table on your balcony and no rule what a table has to be made of. You'll probably find many pictures if you search for "solartisch".
They can be used as table as well (best use a table cloth to avoid scratching the glass, although it is pretty tough).
