It seems like the person in the house looks after the house (including the roof) and the people in the unit block look after theirs and everybody loos after the bits in between – which seems fair. However, anything that impacts on the rest of the strata plan, even visually, might be an issue.
I wouldn’t imagine you’d have too much trouble with the solar panels (but you never know) but putting another door or gate in might raise some concerns. If you’re worried, talk to the other owners or their strata manager. That’s a better idea that wishing, hoping or missing out on a home where you may be perfectly happy.