Does your condo already have some restriction written in the bylaws, or haven't you consulted the building manager yet? The thing is, panels on the facade usually need assembly approval because they change the building's external appearance - even though federal law authorizes solar energy in homes, the condo can veto it for aesthetic or structural reasons. Best thing is to get a copy of the bylaws, talk to the building manager about technical feasibility (sometimes installing on the roof or balcony is easier than on the facade), and if you really want it on the facade, present the project at the next assembly. A lot of buildings in Rio are allowing this now, so there's a chance.