Similarly, in the US, most condo associations are restrictive, and would forbid hanging anything outside a window or balcony, on aesthetic and safety grounds. I

Similarly, in the US, most condo associations are restrictive, and would forbid hanging anything outside a window or balcony, on aesthetic and safety grounds. Installing things on the roof would likely be off limits too, unless you own exclusive rights to it and get approval to make modifications. Fining the unit owners to fix a tenant's dangling solar panel isn't landlord-friendly!